FLORIDA STATE UN IVERSITY
COLLEGE OF H UMAN SCIEN CES
TH E EFFECTS OF STATIC STRETCH IN G ON RUN N IN G ECON OMY AN D
EN DURAN CE PERFORMAN CE IN FEMALE DISTAN CE RUN N ERS DURIN G
TREADMILL RUN N IN G
CH RISTOPH ER D. MOJOCK
A Thesis subm itted to the
Departm ent of N utrition, Food & Exercise Sciences
in partial fulfillm ent of the
requirem ents for the degree of
Master of Science
Degree Aw ard ed :
Spring Sem ester, 2009
The m em bers of the Com m ittee approve the Thesis of Christopher D. Mojock d efend ed
on April 6th, 2009.
Professor Directing Thesis
Com m ittee Mem ber
Com m ittee Mem ber
Bahram Arjm and i, Chair, Departm ent of N utrition, Food and Exercise Sciences
Billie Collier, Dean, College of H um an Sciences
The Grad uate School has verified and ap proved the above nam ed com m ittee m em bers.
This w ork, like everything m eaningful in m y life,
is d ed icated to m y best friend , Suzi.
ACKN OWLEDGEMEN TS
I w ould like to acknow led ge the relentless guid ance and d iscrim inating taste of Lynn
Panton. In ad d ition, w ithout the tireless w ork by Jeong-Su Kim and David Eccles, you
w ould not be hold ing the gem you find in your hand s this d ay. I m ust also thank the
ever-inventive m ind of Jacob Wilson for len d ing a hand to a guy trying to find a
foothold in the m ountain that is hum an perform ance research.
TABLE OF CON TEN TS
List of Tables ................................................................................................................................ vi
CH APTER 1 .................................................................................................................................. 1
H ypotheses................................................................................................................................ 3
Assum ptions ............................................................................................................................. 3
Delim itations ............................................................................................................................ 4
Lim itations ................................................................................................................................ 5
Definition of Term s .................................................................................................................. 5
CH APTER 2 .................................................................................................................................. 7
MTU Stiffness ......................................................................................................................... 11
N eural Activation................................................................................................................... 12
Running Perform ance ........................................................................................................... 13
The Fem ale Athlete ................................................................................................................ 15
CH APTER 3 ................................................................................................................................ 17
Subjects .................................................................................................................................... 17
Prelim inary Measurem ents .................................................................................................. 17
Anthropom etric ...................................................................................................................... 18
Maxim al Oxygen Uptake (VO 2m ax) Testing ..................................................................... 18
Sit-and -Reach .......................................................................................................................... 19
Stretching Protocol ................................................................................................................. 20
Preload and Perform ance Runs ........................................................................................... 20
Com m itm ent Check ............................................................................................................... 21
Dietary Control ....................................................................................................................... 21
Data Analysis .......................................................................................................................... 21
CH APTER 4 ................................................................................................................................ 23
Subject Data and Stretching .................................................................................................. 23
Preload and Perform ance Runs ........................................................................................... 24
Com m itm ent Check ............................................................................................................... 25
CH APTER 5 ................................................................................................................................ 27
APPEN DIX A .............................................................................................................................. 32
APPEN DIX B .............................................................................................................................. 33
APPEN DIX C .............................................................................................................................. 35
APPEN DIX D .............................................................................................................................. 38
APPEN DIX E .............................................................................................................................. 39
APPEN DIX F .............................................................................................................................. 40
REFEREN CES ............................................................................................................................. 42
BIOGRAPH ICAL SKETCH ...................................................................................................... 48
LIST OF TABLES
TABLE 1. Descriptive characteristics of the p articipants (N =12). ...................................... 23
TABLE 2. Acute changes in flexibility follow ing the static stretching protocol (N =12). 24
TABLE 3. Preload run variables (N =12). ............................................................................... 24
TABLE 4. Perform ance run variables (N =12). ...................................................................... 25
TABLE 5. Post-run participant com m itm ent d ata (N =12). ................................................. 26
Stretching has long been a com ponent of the end urance athlete’ s w arm -up routine.
H ow ever, it has been show n that stretching can lead to d ecreased m uscle stiffness and
can be associated w ith d ecreased perform ance in force and pow er prod uction. A recent
stud y from our laboratory has show n that stretching w as associated w ith a d ecrease in
econom y and end urance perform ance in trained m en. PURPOSE: The purpose of this
stud y w as to investigate the acute effects of static stretching on running econom y and
end urance perform ance in trained w om en d istance runners. METH ODS: Tw elve
w om en (H eight:159.4 7.4 cm ; Weight: 54.8 7.2 kg; % bod y fat:19.7 2.8%; Age: 30 9
years) w ere recruited for the stud y and attend ed three laboratory sessions. On the first
visit, anthropom etric and m axim al oxygen consum ption (VO 2m ax) (48.4 5.1
m l/ kg/ m in) measurem ents w ere record ed . The second and third visits occurred
d uring d ays 3-7 of the participants’ m enstrual cycle. Participants p erform ed tw o
sessions of 60-m inute tread m ill runs follow ing a rand om ly assigned 18-m inute static
stretching protocol or 18 m inutes of quiet sitting. The static stretching protocol
consisted of four, 30-second repetitions of five d ifferent exercises d esigned to stretch the
quad riceps, ham strings, calves and gluteal m uscles. During the first 30 m inutes of the
tread m ill run (running econom y), expired gases, heart rate, and rating of perceiv ed
exertion w ere record ed w hile the participant ran at 65% VO 2m ax. During the final 30
m inutes (end urance perform ance), d istance covered , speed , heart rate, and RPE w ere
record ed w hile the participant attem pted to cover as m uch d istance as possible.
Repeated m easures analyses w ere perform ed on the d ata. Significance w as accepted at
p < 0.05. RESULTS: Although there w ere significant increases in flexibility follow ing
the static stretching protocol (29.8±8.3 vs. 33.1±8.1 cm ), there w as no effect of stretching
on VO 2 (33.7±3.2 vs. 33.8±2.3 m l/ kg/ m in), calorie expend iture (270±41 vs. 270±41 kcal),
heart rate (157 10 vs. 160 12 bpm ) or end urance perform ance (5.5 0.6 vs. 5.5 0.7 km ).
CON CLUSION : These find ings ind icated that stretching d id not have an ad verse effect
on end urance perform ance in trained w om en, w hich is contrary to the find ings of our
previous stud y in m en. This could m ean the end urance perform ance d ecrem ents
previously associated w ith stretching are not related to increases in flexibility in trained
w om en.
CH APTER 1
BACKGROUN D AN D SIGN IFICAN CE
N um erous stud ies have show n that the prop osed benefits of static stretching
prior to event participation such as increased range of motion (ROM), injury prevention
and perform ance enhancem ent, are in fact d eleterious to perform ance by d ecreasing
pow er [1-7], m axim um strength [4, 8, 9] and sprint perform ance [10, 11]. The increases
in ROM experienced from stretching are significant [12-14], but d o not correlate to
increases in injury prevention  and / or im provem ents in perform ance [1, 2]. The
d ecreases in perform ance associated w ith static stretching have been attributed to
d eclines in m u sculotend inous unit (MTU) stiffness [2, 5, 16-21] and d ecreased neural
activation of the skeletal m uscles [4, 6, 17, 19, 22].
A com pliant MTU increases the slack on the tend on and d oes not allow the force
generated by the contractile com ponent to be transm itted to the skeletal system as
effectively as a stiff u nit [5, 21]. The effects of a com pliant MTU w ere found to d ecrease
m axim al voluntary contraction (MVC) of the knee extensors and plantar flexors by
alm ost 10% . In ad d ition, one stud y reported a 7.4% d ecrease in counter -m ovem ent
jum p perform ance accom panied by a 2.8 % d ecrease in MTU stiffness . An optim um
stiffness m ight exist that m axim izes the m agnitud e of elastic energy return. MTU
stiffness and the extension prod uced by an im posed force d eterm ine the am ount of
energy that can be stored . Thus, static stretching ind uces d eclines in MTU stiffness thus
significantly red ucing the energy available for m ovem ent [16, 20, 23].
Along w ith the d ecreases in MTU stiffness, stud ies have reported d ecreases in
m uscle activation [2, 4, 6, 19] as ind icated by integrating electrom yographic record ings
(IEMG) activity. For exam ple, one stud y reported d ecreased m uscle activity fo r up to 2
hours follow ing a static stretch protocol . Static stretching increases inhibition of the
m otor units, of the m uscle being stretched and its synergist, by facilitating the golgi
tend on organ (GTO) [22, 24]. Moreover, stretch d urations as short as 10-15s [25, 26] at
intensities as low as 50% of the point of d iscom fort (POD)  w ith as little as one stretch
per m uscle group  have been show n to increase m uscle length, effectively red ucing
MTU stiffness and neu ral activation.
Muscular end urance has received less attention to d ate regard ing the effects of
stretching on perform ance. Muscular end urance has been d efined as the num ber of
consecutive repetitions a person can lift a specified w eight or the length of tim e the
person can hold a specific w eight . Follow ing 15 m inutes of passive static stretching
of the hip, thigh and calf, knee flexion perform ed w ith a load equal to 50% of the
subjects’ bod y w eight w as red uced from 16 to 11 repetitions. The proposed
m echanism for the d ecrease w as that the stretch regim en placed a proportion of motor
units into a fatigue-like state prior to initiation of the end urance test; a d ecrease in the
pool of motor units available for activation could hasten fatigue and lead to d ecreases in
perform ance .
Work in the field of end urance perform ance has id entified m axim al oxygen
uptake (VO 2m ax) and econom y as the prim ary lim iting factors [28, 29]. VO 2m ax
provid es a quantitative m easure of a person’ s capacity for aerobic ad enosine
triphosphate (ATP) resynthesis and acts as an objective m easure of card iorespiratory
function . Econom y d escribes the rate of oxygen consum ption p er unit bod y m ass
w hen running at a constant pace . Greater stiffness allow s ind ivid uals to gain m ore
benefit from passive elastic m echanism s than m ore flexible ind ivid u als and thus these
ind ivid uals incur low er energy costs d uring end urance events [32, 33]. The largest
contributor to increased aerobic d em and is the increased m u scle force required by the
knee w hen the m uscle length is increased . The m ost econom ical runners typically
show higher contraction strength, greater stiffness and higher energy storage capacity
w hen com pared to runners w ith sim ilar VO 2m ax values . Ru nning speed is a
function of strid e length and strid e rate; d ecreased stiffness accom panies d ecreased
strid e rate and this lead s to longer ground contact tim es. The longer ground contact
tim es are an attem pt to com pensate for the d ecreased strid e rate by increasing strid e
Unlike the areas of sprint perform ance, m uscular strength and m uscular
end urance perform ance, there are few d ata on the effects of stretching prior to long
d uration aerobic end urance events. The only current stud y to d ate evaluating long
d istance end urance perform ance found a significant increase in energy expend iture
follow ing stretching d uring a 30-m inute run, 425 50 kcals versu s 405 50 kcals. In
ad d ition, d istance covered d uring a 30-m inute perform ance run, 3.7 0.7 m iles versu s
3.6 0.6 m iles, w as significantly greater in the non -stretched cond ition . Stud ies
have show n a negative linear relationship exists betw een leg stiffness and econom y,
m easured by m etabolic energy costs (O 2 consum ed ) at a given velocity, w hile running
[32, 37]. Also, another stud y found that runners’ stiffness low ers as they near fatigue
in a tim e-to-exhaustion trial . Low er stiffness lead s to increased ground contact
tim e  w hich m ay allow a greater percentage of energy stored w ithin tend inous tissue
to d issipate into the ground d uring the supp ort phase of running. As potential energy
low ers, there m ay be greater reliance on intrinsically generated force from m uscular
contraction lead ing to greater fatigue and d ecreased perform ance. In ad d ition, there
have been no stud ies evaluating the effects of stretching in w om en, w ho have been
show n to be m ore flexible than their m ale cou nterparts . Therefore, the purpose of
this stud y w as to investigate the effects of static stretching on running econom y and
end urance perform ance d uring tread m ill running in trained w om en runners.
H ypothesis 1: Static stretching w ill d ecrease aerobic perform ance d uring a 30-m inute
perform ance tread m ill run.
H ypothesis 2: Static stretching w ill d ecrease running econom y d uring a 30-m inute
preload tread m ill run.
H ypothesis 3: Static stretching w ill increase total kilocalorie expenditure d uring a 30-
m inute preload treadm ill run.
This stu d y includ ed the follow ing assum ptions:
1.) All subjects accurately reported their past and current exercise histories.
2.) Subjects accurately reported their m enstrual cycles.
3.) Subjects follow ed instructions given to them regard ing the m aintenance of
current lifestyle (e.g., d iet and d aily physical activity) outsid e of the prescribed
4.) All laboratory equipm ent accurately record ed m easurem ents over the course of
5.) All subjects prod uced m axim um efforts d uring VO 2m ax testing and the
perform ance run.
6.) Subjects reliably paced them selves over a 60-m inute tim e trial run.
7.) Subjects stretched to the point of mild d iscom fort d uring static stretching
This stu d y had the follow ing d elim itations:
1.) Tw elve trained w om en, d eterm ined by a VO 2m ax of > 45 m l/ kg/ min currently
running at least 20 m iles a w eek and prior com petition in at least 10K-d istance
running events, betw een the ages of 18-45 years w ere recruited from the
2.) Subjects w ere healthy, w ithout und erlying d isease or m ed ical cond itions and
free of any contraind ications to tread m ill end urance testing.
3.) Subjects w ere non-sm okers and not taking any ergogenic aid s.
4.) Subjects w ere regularly m enstruating.
5.) Subjects w ere tested betw een d ays three and seven of the follicular p hase.
6.) Subjects had their VO 2m ax m easured on visit one and com pleted a
fam iliarization run of the experim ental protocol. Visit tw o occurred at least one
w eek after visit one and w as sched uled d uring d ays three through seven of the
follicular phase. Experim ents on visits tw o and three w ere perform ed after a 3-
hour fast und er stretching and non -stretching cond itions follow ing a
rand om ized , counterbalanced ord er. On visit tw o, the subjects perform ed the
stretching or non-stretching routine before beginning a 60-m inute running
protocol on a tread m ill. The protocol consisted of a 30-m inute preload at 65% of
the subjects’ VO 2m ax and a 30-m inute perform ance run. On visit th ree, at least
21 d ays later, subjects perform ed the pre-run routine that they d id not d o on visit
tw o before beginning the 60-m inute tread m ill run. Visits tw o and three w ere
perform ed at the sam e tim e of d ay and subjects w ore the sam e clothing and
shoes for all exercise sessions.
This stu d y contained the follow ing lim itations:
1.) Geographical bias m ay be present since the su bjects w ere only recruited from the
2.) Diet, sleep, training and other out-of-laboratory variables w ere not controlled
throughout the stud y. H ow ever, subjects w ere ad vised to m aintain their current
training volum e as w ell as replicate their d iets for 3 d ays lead ing up to testing.
3.) A previous stud y w as recently com pleted w ithin the d epartm ent of N utrition,
Food and Exercise Sciences investigating the effects of static stretching on trained
m en and the results of that stud y m ay bias the subjects w ho volu nteered from
w ithin the d epartm ent.
4.) Although subjects had sim ilar VO 2m ax values and training volum es, m inim u m
and m axim um perform ance stand ard s based on race tim es have not been
Definition of Term s
Maxim al Oxygen Uptake (VO2m ax): A quantitative m easure of a person’ s capacity for
aerobic ad enosine triphosphate (ATP) resynthesis and acts as an objective m easure of
card iorespiratory function .
Point of Mild Discom fort (POD): Stretching the m uscle to the greatest voluntary length,
beyond w hich the participant feels injury m ight occur .
Maxim al H eart Rate (H Rm ax): H ighest heart rate achieved d uring the VO 2m ax testing.
Musculotend inous Unit (MTU): The m uscle, tend on and aponeurosis w hich cause
m ovem ent of the skeletal system .
MTU Stiffness: The overall resistance to d eflection or d eform ation, resulting from both
the elastic and contractile com ponents of the MTU, by an applied force .
Running Econom y: The energy required to m aintain a constant velocity w hen running
CH APTER 2
REVIEW OF LITERATURE
Current recom m end ations from governing authorities on exercise, such as the
Am erican College of Sports Med icine and the N ational Strength and Cond itioning
Association, prescribe stretching as part of the w arm -up in ord er to facilitate the
transition from rest to exercise. They suggest the w arm -up begin w ith five to fifteen
m inutes of low -intensity, large m uscle group activity and conclud e w ith five to ten
m inutes of static stretching of large m uscle groups held to the point of mild d iscom fort
for thirty second s. H ow ever, recent find ings suggest that stretching prior to athletic
com petition m ay actually hind er pow er [1-7], m axim um strength [4, 8, 9] and sprint
perform ance [10, 11].
The m ajority of stud ies investigating the im pact of stretching on perform ance have
replicated current recom m end ations and utilized static stretching protocols as part of
their experim ental m od el. A static stretch is d efined as a slow , constant stretch hold ing
the end position at the end of the range of motion. This end range of motion is term ed
the point of mild d iscom fort (POD), the greatest voluntary length attainable, beyond
w hich the participant feels injury w ould occu r . For m ost stud ies, follow ing a light
w arm -up of cycling or w alking, tw o to four stretches per m uscle group are held at the
POD for fifteen to thirty second s [1-7, 9-11].
Muscular pow er events are those that require force to be prod uced rapid ly and
includ e jum ping m ovem ents like the ones tested by Behm and Kibele . Follow ing a
five-m inute w arm -u p at 70 w atts on the cycle ergom eter, subjects perform ed tw o
repetitions each of five d ifferent jum ping m ovem ents on a force plate. Jum p tests
includ ed a 24cm d rop jum p, counterm ovem ent jum p -short am plitud e (CMJ SA)
em phasizing a fast stretch shortening cycle and m inim al knee flexion,
counterm ovem ent jum p em phasizing a slow stretch shortening cycle to a knee flexion
of 70 (CMJ 70), counterm ovem ent jum p w ith a self selected pace and knee d epth (CMJ
Preferred ) and a concentric only squat jum p w ith an initial knee position of 70 . The
jum p tests w ere follow ed by one of four d ifferent pr otocols, four repetitions of 30-
second static stretch at 50%, 75% and 100% POD or a control cond ition. Percentages of
POD w ere d eterm ined w ith a m anual m uscle strength tester used to quantify the stress
on the lim b d uring stretching. Unilateral kneeling knee flexion w ere used to stretch the
quad riceps, supine hip flexion w ith extend ed knee to stretch the ham strings and ankle
d orsiflexion w hile stand ing upright on an elevated platform to stretch the triceps surae
w ith gastrocnem ius em phasis. Investigators found ju m p perform ance to be
significantly red uced across all five jum p m easures follow ing static stretching at each
intensity. The m ean d ecreases in jum p height w ere 5.3% in d rop jum p, 3.8% in squat
jum p, 5.6% in CMJ 70, 3.6% in CMJ preferred and 4.6% in CMJ SA .
Knud son and colleagu es used an isom etric hand grip d yna m om eter to test
m uscular strength, the ability to prod uce m axim al force. Isom etric grip strength has
been show n to be a reliable ind icator of overall strength w ith consid erable norm ative
d ata and clinical utility . Follow ing a one-m inute w arm -up of grad ual sw inging of a
tennis racket, em phasizing w rist flexion and extension in the tra nsverse plane, subjects
perform ed four m aximal effort attem pts on the hand grip d ynam om eter separated by
one-m inute rest intervals. Three to four attem pts w ere need ed to red uce any learning
and w arm -up effects on hand grip strength testing. The su bjects th en perform ed 10
three-second m axim al effort attem pts separated by one-m inute rest intervals. The
control group d id nothing d uring the rest period s and the experim ental group
perform ed ten-second static stretching of the w rist flexors to the POD. N ot only d id the
stretching group record significantly low er values in grip strength in trials 4 through 10
w hen expressed as a p ercentage of the initial grip strength, up to 9.02% low er (97.6 ± 6.9
vs. 88.8 ± 8.4 lbs), but also strength d eclined at a faster rate. In the control group, m ean
grip strength w as best fit by a linear equation pred icting a grad ual d ecline in
perform ance; the m ean grip strength of the static stretching group w as best fit by a
logarithm ic equation pred icting an exponential d ecline in grip strength .
Muscular end urance has been d efined as the num ber of consecutive repetitions a
person can lift a specified w eight or the length of tim e the person can hold a specific
w eight . A strong correlation exists betw een strength and end urance; consid ering
stud ies have show n d ecrem ents in m u scular strength follow ing static stretching it w as
expected that m uscular end urance w ould follow the sam e trend . In a stud y by N elson
and colleagues, investigators analyzed the effects of static stretching on subm axim al
knee-flexion exercise using tw o d ifferent protocols . Tw o protocols w ere used in
ord er to d eterm ine the reliability of measurem ents. The static stretching treatm ent for
both experim ents consisted of tw o stretches, the sit-and -reach and a heel cord
d orsiflexion stretch. First, four unassisted repetitions of the sit -and -reach test w ere
perform ed . Once com pleted , four repetitions of the heel cord stretch w ere perform ed .
After the first set of heel cord stretches, a second set of four sit-and -reach stretches w ere
perform ed , this tim e the stretching w as d one w ith assistance from the investigators.
Finally, a second set of four heel cord stretches w ere perform ed .
Experim ent one consisted of tw o consecutive d ays of prone knee-flexion using a
w orkload equal to approxim ately 40% and 60% of the person’ s bod y w eight, for a total
of four laboratory visits. Tw o groups w ere rand om ly assigned one of tw o treatm ents,
10 m inutes of quiet sitting or 15 m inutes of static stretching of the hip, thigh and calf
m uscle groups. Each testing d ay the subjects entered the laboratory, perform ed a sit -
and -reach test, the assigned treatm ent, a second sit-and -reach test and finally the knee-
flexion m uscu lar end u rance test. Follow ing the static stretching protocol, investigators
found the num ber of knee-flexion repetitions to failure d ecreased by 2.3 4.3 and 3.5
3.1 lifts d uring the 40% and 60% trials, respectively. This d ecline in perform ance
represents a 9.8% and 24.4% d ecrease in perform ance at 40% and 60%, respectively .
The d eclines in perform ance w ere associated w ith an increase in joint ROM of 11.78%
and 15.75% d uring the 40% and 60% trials, respectively.
Experim ent tw o consisted of four d ays, separated by one w eek of rest, of prone
knee-flexion using a w orkload equal to approxim ately 50% of the person’ s bod y
w eight. The rest w eek w as d esigned to lim it perform ance recall from previous testing
sessions and red uce any m uscle soreness. Again, tw o groups w ere rand om ly assigned
one of tw o treatm ents, 10 m inutes of quiet sitting or 15 m inutes of static stretching of
the hip, thigh and calf m uscle groups. Each testing d ay the subjects entered the
laboratory, perform ed a sit-and -reach test, the assigned treatm ent, a second sit-and -
reach test and finally the knee-flexion m uscu lar end urance test. Sim ilar results w ere
found in experim ent tw o, follow ing an acute bout of static stretching, the m axim um
num ber of lifts d ecreased from 16.0 5.9 in the control cond ition to 11.6 6.0 in the
stretched cond ition. This represents a 27.5% d ecrease in perform ance and w as
associated w ith a 17.7% increase in joint ROM . The proposed m echanism behind
this im paired perform ance is that the static stretching treatm ents placed a proportion of
the m otor units into a fatigue-like state prior to the knee flexion exercise d ecreasing the
total num ber of motor units available for the lift, hastening overall fatigue and
d ecreasing perform ance.
The only current stud y to d ate evaluating the effects of static stretching on long
d istance end urance perform ance w as d one by Wilson and colleagu es . A 60-m inute
tread m ill protocol, consisting of a 30-m inute preload run and a 30-m inute perform ance
run, w as u sed to evalu ate perform ance follow ing an acute bout of static stretching in
trained m ale d istance runners. Su bjects perform ed the 60-m inute protocol, und er
stretching and non-stretching cond itions, in a rand om ized ord er separated by at least
one w eek. Stretching consisted of 15 minutes of static stretching using five d ifferent
exercises for the quad riceps, ham strings, gluteus m axim u s, anterior and posterior
calves, w hile the non-stretching cond ition consisted of 15 minutes of quiet sitting. The
30-m inute preload run w as perform ed at 65% of the subject’ s pred eterm ined VO 2m ax
and w as used to m easure running econom y as d eterm ined by changes in total calorie
expend iture. During the 30-m inute perform ance run, su bjects w ere instructed to cover
as m uch d istance as possible w ithout view ing the speed or d istance covered . Follow ing
an acute bout of static stretching, investigators found a significant increase in energy
expend iture d uring the preload run und er stretched , 425 50 kcals, versus the non-
stretched cond ition, 405 50 kcals. In ad d ition, d istance covered d u ring the
perform ance run, 3.7 0.7 m iles (non-stretched ) versus 3.6 0.6 m iles (stretched ), w as
significantly greater in the non -stretched cond ition . The proposed m echanism s
behind the d ecreases in perform ance are d eclines in MTU stiffness [2, 5, 16-21] and
d ecreased neural activation of the skeletal muscles [4, 39-41].
The MTU consists of the m uscle, tend on and aponeurosis exerting force on the
skeletal system to cause m ovem ent. The elastic com ponents of mu scle can be stretched ,
absorb energy and enhance force d evelopm ent; the m ost im portant in translating
stretch into force are the series elastic com ponents of muscle, the tend on and
aponeurosis . The process by w hich the series elastic com ponents enhance the
d evelopm ent of force is called the stretch -shortening cycle, potential energy is stored
d uring the stretch and is then released d uring the im m ed iate cont raction of the m uscle
Active MTU stiffness, stiffness und er stim ulated cond itions, has been proposed as
a contributing factor in force prod uction . One stud y found MTU stiffness, as
d eterm ined by a force plate record ing the resultant d am ped oscillatio ns from applied
external force d uring an isom etric bench -press, w as significantly related to isom etric
and concentric rate of force d evelopm ent (RFD) (N / s), at .78 and .65, respectively.
When the five stiffest subjects w ere com pared to the 5 least stiffest subjects, 12,848.2
2867.0 N / m vs. 8302.3 1636.2 N / m , a d ifference of 7884 N / s for the isom etric RFD
and 3450 N / s for the concentric RFD w ere found . A stiff MTU w ould result in
red uced length and greater shortening velocity allow ing m ore effective prod uction of
force from the contractile com ponent d uring isom etric and concentric actions d ue to the
im proved length-tension and force-velocity relationships. In ad d ition, a stiff MTU w ill
partially d eterm ine how effectively and rapid ly internal forces generated by the
contractile com ponent are initially transm itted to the skeletal system .
Another stud y m easured MTU stiffness in the triceps surae m uscle com plex using
a sim ilar calculation based on the vertical force oscillations typical of d am ped harm onic
m otion. In this stud y, tw o static stretches consisting of three sets of 30s stretches, found
active MTU stiffness red uced by 2.8%. This im pairm ent w as associated w ith a 7.4%
d ecrease in counter m ovem ent jum p height. If static stretching red uced the stiffness of
the series elastic com p onent, elastic potentiation m ay have been com prom ised .
N eural Activation
The possible m echanism s behind the neural com ponent of d ecreases in
perform ance are changes in m otor unit activation, firing rate and altered reflex
sensitivity. The changes in m otor unit activation w ould m anifest them selves in the
form of d ecreased IEMG activity, w hile firing frequency is estim ated from zero crossing
rate . The use of electrical stim ulation from surface electrod es has been u sed to
sim ulate neural im p ulses to the m otor units; the resultant tw itch responses can be
com pared to voluntary activity helping d istinguish betw een m echanical and neural
In a stud y utilizing external electrical stim ulation and IEMG m easurem ents,
researchers found a 9.5% d ecrease in isom etric m axim al volu ntary contraction (MVC) of
the quad riceps im m ed iately follow ing static stretching. The static stretch w arm -up
consisted of five m inutes of light w ork on the cycle ergom eter to raise bod y tem perature
and six stretches for the quad riceps, ham strings and calves consisting of three sets each
of 45s held to POD; stretches includ ed stand ing straight knee and stan d ing bent knee to
stretch the m uscles of the calves, m od ified hu rd le and supine hip flexion to stretch the
ham strings and prone buttocks kick and kneeling buttocks kick to stretch the
quad riceps. In ad d ition to the 9.5% d ecrease in MVC of the quad riceps, w hen
investigators used electrod es to evoke m aximal force d uring a voluntary MVC, they
w ere able to d eterm ine the percentage of muscle fibers not activated by the voluntary
com m and alone; this inactivity w as increased 5.4% follow ing an acute bout of static
stretching. Although non -significant, there w as a trend tow ard d ecreases in quad ricep s
IEMG activity of 15.1% and 16.5% im m ed iately and 120-m inutes post stretching,
respectively. Researchers found no change in the evoked contractions d uring peak
tw itch or tetanic trials and therefore conclud ed the d ecreases in MVC w ere the result of
inhibited neural activation .
Another stud y em ployed the use of one unassisted and three assisted static
stretches of the quad riceps, four stretches for four sets each of 30s held to POD.
Measurem ents of d om inant-leg knee extension peak torque (PT)(N m ) and m ean pow er
output (MP)(W) at 60° / s and 300°/ s w ere record ed on an isokinetic d ynam om eter, an
overall d ecrease of 2.8% in PT and 3.2% in MP w ere found follow ing static stretching.
The d ecreases in PT and MP w ere associated w ith d ecreases in IEMG am plitud e
( Vrm s) of 7.6% and 4.4% at 60°/ s and 300°/ s, respectively .
In regard s to reflex activity, one stud y investigated the effects of repeated passive
stretching (RPS) of the gastrocnem ius and soleus m u scles. Repeated d ynam ic
stretching of the calf m uscles by an ankle ergom eter ind uced RPS. The m axim al H -
reflex, response of the Ia afferent fibers, d eclined by 46.1% follow ing the RPS, how ever
the M w ave, m easure of muscle fiber excitation and im pulse cond u ction, response w as
not affected . This find ing w ould suggest a red uction in the excitatory d rive from the Ia
afferents onto the -m otorneurons, possibly d ue to the d ecreased m uscle spind le
activity related to increased m uscle com pliance. Investigators also noted a non -
significant d ecrease of the H -reflex in the non-stretched leg, attributing these effects to a
central inhibition. In ad d ition, the zero cross rate (ZCR) d uring 50% MVC, an estim ate
of the m otor unit firing frequency, d ecreased 12.2%. An increase in m otor unit
synchronization w ould be the only other explanation for a d ecrease in ZCR; how eve r,
since there w as no increase in EMG am plitud e, the m ost likely source w as a d ecrease in
m otor unit firing frequency .
Running Perform ance
Econom y is used to d escribe the rate of oxygen consum ption per unit bod y m ass
w hen running at a constant pace. In a stud y of male long -d istance runners, econom y
w as m easured w hile running 15 m inutes at 3.0, 3.5 and 4.0 m / s. VO 2 values w ere
averaged from four m inutes running at stead y state for each velocity, 10 m inutes of rest
separated each 15 m inutes of running . The m ost econom ical ru nners typically
show higher contraction strength, greater stiffness and higher energy storage capacity
w hen com pared to runners w ith sim ilar VO 2m ax values . The triceps surae MTU
force generated d uring an ankle plantarflexion MVC w as 2028 N in the highest running
econom y group versus 1572 N and 1432 N in the m od erate and low econom y groups,
respectively; stiffness m easured d uring the MVC for the highest econom y group w as
34.4 kN com pared to 23.7 kN and 20.6 kN for the m od erate and low groups,
The support phase of running has an eccentric and concentric phase; d uring the
eccentric phase m echanical energy is stored in the series elastic com ponents of the leg
extensor m uscles and red uces the energy expend iture w hen it is released d uring the
concentric phase. In a stud y involving eight m id d le d istance runners, investigators
found an inverse relationship betw een stiffness and m etabolic energy cost at a given
velocity; the greater the leg stiffness, the low er the energy cost of running . Energy
cost of running w as calculated by m easuring VO 2, collected in Douglas bags, w hile
running at 90% VO 2m ax. Bod y d isplacem ents w ere record ed w ith a kinem atic arm
d uring running and used to calculate stiffness an d resonant frequency (RF), w hile
optical pressure sensors on the shoes captured step frequency (SF). A spring -m ass
m od el w as u sed to d eterm ine the relative frequency d ifferences betw een the runners’
actual SF and the calcu lated RF of the spring-m ass system . Investigators d efined RF as
the frequency that perm its one to m aintain an oscillating m ovem ent at given am plitud e
w ith m inim al energy expend iture; the RF is based on the runners’ bod y w eight and the
stiffness of the spring. Ru nners consu m ed less energ y w hen higher levels of stiffness
w ere m aintained , RF of the m od el w as close to the real SF .
Greater stiffness allow s ind ivid uals to gain m ore benefit from passive elastic
m echanism s than m ore flexible ind ivid uals and thus these ind ivid u als incur low er
energy costs d uring end urance events [32, 33]. Ru nning speed is a function of strid e
length and strid e rate; d ecreased stiffness accom panies d ecreased strid e ra te and this
lead s to longer ground contact tim es, the longer ground contact tim es are an attem pt to
com pensate for the d ecreased strid e rate by increasing strid e length . The largest
contributor to increased aerobic d em and is the increased m u scle force required by the
knee w hen the m uscle length is increased  as occurs follow ing static stretching.
Com bine that w ith the increased ground contact tim e that follow s static stretching ,
and the result is a greater percentage of energy stored w ithin tend inous tissue w ill
d issipate into the ground d uring the support phase of running placing greater d em and
on the leg m uscles to generate force from concentric m uscle contraction.
The Fem ale Athlete
The m ajority of stud ies investigating the effects of stretching on physical
perform ance have focu sed on m en, and in the stud ies w here w om en w ere used there
w as no control of the m enstrual cycle; d ifferences in horm one levels throughout the
m enstrual cycle m ay cause d ifferent responses in w om en. Phases of the m enstrual cycle
are characterized by varying estrogen and progesterone levels; low levels of estrogen
and progesterone in the early follicular phase (d ays 3 through 7), higher levels of
estrogen and low levels of progesterone in the m id -follicular phase (d ays 8 through 13)
and high levels of estrogen and progesterone d uring the m id -luteal phase (d ays 19
through 22) [43-45]. Proposed second ary physiological effects of the fem ale m enstrual
cycle horm ones, estrogen and progesterone, includ e changes in resp iratory and
therm oregulatory responses; how ever, m ost stud ies investigating the d eterm inants of
VO 2m ax, fuel availability, circulation and respiration, report n o significant changes over
the m enstrual cycle [43, 46, 47]. In one stud y investigating the effect of menstrual cycle
phase on VO 2m ax, su bjects perform ed VO 2m ax tests on d ays 3-early follicular (43.0
2.3m l/ kg/ m in), 10-m id -follicular (42.7 2.3m l/ kg/ m in) and 21-m id -luteal (42.5
1.8m l/ kg/ m in), no significant d ifferences w ere found .
Although stud ies have show n no effect of menstrual cycle horm one variation on
VO 2m ax perform ance, a num ber of stud ies have reported changes in bod y tem perature
d uring the follicular and luteal phases [44, 45]. One stud y used a sixty-m inute,
subm axim al (65% VO 2m ax) cycle ergom eter protocol to m easure changes in heart rate
(H R), rating of perceived exertion (RPE), rectal and skin tem peratures in aerobically
trained fem ale athletes d uring the m id -follicu lar (seven d ays before ovulation) and m id -
luteal (seven d ays after ovulation) phases of the m enstrual cycle . H eart rate values
w ere significantly low er in the follicular phase than in the luteal phase, both at rest (71
vs. 83 b/ m in) and at sixty m inutes of exercise (151 vs.162 b/ m in). Ratings of perceived
exertion values w ere sim ilar d uring the first fifty m inutes of exercise, and then
increased slightly but significantly in the luteal phase. Rectal tem perature reached a
plateau after forty m inutes of exercise d uring the m id -follicular phase (38.3 C), w hereas
d uring the m id -luteal phase rectal tem perature continued to increase throughout the
entire exercise bout (38.9 C), never reaching equilibrium . Skin tem p erature w as not
affected by the m enstrual cycle phases and reached a plateau after tw enty m inutes of
exercise in both phases . The higher tem peratures experienced d uring the luteal
phase of the m enstrual cycle m ay lead to increased therm oregulatory and
card iovascular strain; these changes could negatively im pact perform ance and
efficiency d uring prolonged end urance exercise.
Stud ies have also show n fem ale athletes to have low er stiffness values than their
m ale counterparts [38, 48, 49]. In one stud y, researchers used a tw o-legged hopping
task on a force platform to m easure active m uscle stiffness . Su bjects perform ed
thirty hop s at three d ifferent frequencies, 2.5 H z, 3.0 H z and at the subject’ s self-
selected frequency. Mean leg stiffness values w ere alm ost 29% greater in m ales (33.9
8.7 kN / m ) than in fem ales (26.3 6.5 kN / m ), w ith significant d ifferences at each of the
hopp ing frequencies . If MTU stiffness plays a m ajor role in perform ance d uring
running, fem ale athletes m ay respond significantly d ifferent than their m ale
counterparts to stretching before exercise. Therefore, the purpose of the present stud y
w as to investigate the acute effects of static stretching on long d istance end urance
perform ance and running econom y in trained fem ale runners und er stretching and
non-stretching cond itions by com paring energy expend iture and d istance covered
d uring a 60-m inute ru nning protocol on a tread m ill.
CH APTER 3
RESEARCH DESIGN AN D METH ODS
Tw elve trained non-sm oking w om en, d eterm ined by a VO 2m ax of > 45
m l/ kg/ m in currently running at least 20 m iles a w eek, betw een the ages of 18-54 years
w ere recruited from the Tallahassee area (Append ix A). These m inim um requirem ents
w ere established to ensure all participants w ere low -risk accord ing to ACSM guid elines
and w ould perform consistently on the treadm ill run over m ultiple visits. All
participants w ere inform ed of the physical risk involved in tread m ill running,
com pleted a health history and m enstrual cycle questionnaire (Append ix B) and signed
a w ritten inform ed consent statem ent (Append ix C) approved by the University
Institutional Review Board (Append ix D) before participating in the stud y. Participants
w ere free of any contraind ications to tread m ill end urance testing and w ere regularly
Prelim inary Measu rem ents
Participants reported to the laboratory for prelim inary testing and to fam iliarize
them selves w ith the tread m ill protocol. On the first visit, participants reported to the
laboratory after a 3-hour fast; bod y com position w as estim ated using the sum of three
skinfold s (triceps, suprailiac and anterior thigh)  and VO 2m ax w as d eterm ined
using a progressive grad ed exercise test to exhaustion. After approxim ately ten
m inutes of rest, the participants 65% intensity level w as d eterm ined . The participants
w ere then fam iliarized w ith the experim ental protocol, a 60-m inute run on a m otor-
d riven tread m ill consisting of a 30-m inute preload run at 65% VO 2m ax and a 30-m inute
perform ance run w here participants attem pted to cover as m uch d istance as possible by
controlling the speed of the tread m ill w ithout being able to view the d istance covered
or current speed . After at least one-w eek recovery and betw een d ays three and seven of
the follicular phase of their m enstrual cycle, p articipants perform ed the experim ental
protocol on tw o separate occasions separated by at least 21 d ays und er stretching and
non-stretching cond itions. Experim ents w ere perform ed after a 3-hour fast.
Experim ental cond itions w ere assigned in a rand om ized , counterbalanced ord er by
flipping a coin for the first participant recruited then alternating cond itions for each
Running econom y w as d eterm ined as the total kilocalorie expend iture an d
average VO 2 for the 30-m inute preload , w hile end urance perform ance w as m easured as
the total d istance covered d uring the 30-m inu te perform ance run. The non -stretching
protocol consisted of 15 minutes of quiet sitting, w hile the stretching protocol consis ted
of 15 minutes of static stretching using five d ifferent exercises for the quad riceps,
ham strings, calf and gluteus m u sculature. Participants w ore the sam e clothes and
running shoes for all sessions.
For each visit, participants reported to the laboratory after a 3-hour fast. H eight
in centim eters and w eight in kilogram s w ere m easured on a Seca scale (H anover, MD).
Bod y fat percentage was d eterm ined by the sum of three skinfold s, triceps, suprailiac,
and thigh, using Lange calipers (Beta Technologies Santa Cruz, CA) and follow ing the
proced ures d eveloped by Jackson and Pollock . The Siri equation w as u sed to
calculate bod y fat percentage .
Maxim al Oxygen Uptake (VO 2m ax) Testing
For all exercise sessions, gas exchange and ventilatory param eters w ere
m easured by ind irect calorim etry using a m etabolic cart system (Tru em ax 2400
Metabolic Measurem ent System , Consentius Technologies, Sand y, UT). The m etabolic
system w as calibrated accord ing to m anufacturer’ s recom m end ations. Briefly, the
m etabolic system w as flow calibrated w ith a 3L calibration syringe (no.5530, H ans
Rud olph, Inc., Kansas City, MO) and gas calibration w as perform ed using a gas m ixture
of know n concentrations of O 2 and CO 2 (16%O 2; 4%CO 2, Scott Med ical Prod ucts,
Plum stead ville, PA). Environm ental tem perature, hum id ity and barom etric pressure
w ere m easured using an ind oor clim ate m onitor (Perception II TM, Davis Instrum ents,
H ayw ard , CA) and participant d ata w ere entered into the m etabolic cart. The
participants w ere fitted w ith a head piece and nose clip. A m outhp iece (Survivair BLUE
1, Com asec Inc., Enfield , CT) attached to a nine-foot breathing tube (no. 112263 2700B
and 666021, H ans Rud olph Inc., Kansas City, MO) w as used to collect expired air and
d eliver it to the m etabolic cart system d uring all the exercise sessions. H eart rate (H R)
w as m onitored using a Polar TM heart rate m onitor.
On the first visit, follow ing a 3-hour fast, the VO 2m ax w as d eterm ined using a
progressive exercise test to exhaustion protocol. VO 2m ax w as d eterm ined on a
Wood w ay Tread m ill (Waukesha, WI). The initial velocity a nd inclination w as 10 km h -1
and a 1% grad ient . Every m inute the tread m ill speed w as increased 2km / h until
the participant could no longer m aintain the pace. The criterion for achievem ent of
VO 2m ax w as fulfilled by reaching at least three of the follow ing: 1) a plateau in oxygen
consum ption for an increase in exercise intensity (< 2.0 m l/ kg/ m in in crease), 2)
respiratory exchange ratio = 1.1, 3) H R = 85% of an age pred icted m axim um (as
d eterm ined by 220-participant’ s age), 4) voluntary cessation of the test by the
participant and 5) a rating of perceived exertion (RPE) > 18 . A true plateau of
oxygen consum ption is rare because VO 2m ax is an effort d epend ent m easure influenced
by the participant’ s m otivation and the observer; therefore the participants w ere
verbally encouraged d uring the VO 2m ax test by the observers to help elicit as close to a
true m axim al value as possible .
Sit-and -reach m easurem ents w ere cond ucted using a sit-and -reach box at each
visit. Participants sat, w ithout shoes, on the floor w ith legs extend ed and soles of the
feet flat against the box. The participant exhaled , d ropped her head betw een her arm s
and slow ly reached forw ard w ith both hand s as far as possible and held the end point
for approxim ately tw o second s. The m ost d istan t point reached w ith the fingertips w as
record ed as the score. On non -stretching d ays, a baseline m easurem ent w as record ed
after the anthropom etric d ata w ere collected and prior to the quiet sitting. A final sit -
and -reach test w as perform ed after the perform ance run. On stretching d ays, a sit-and -
reach test w as perform ed prior to and im m ed iately follow ing the stretching protocol.
Again, a final sit-and -reach test w as perform ed after the perform ance run. Only one
attem pt w as executed at each of the sit-and -reach m easurem ents, this d esign w as to
ensure no lasting effects of the sit-and -reach test on the non-stretching cond ition.
Follow ing five m inutes of tread m ill w alking at 5.5 km / h, four repetitions of each
of five stretching exercises w ere perform ed w ith a total stretching tim e of 18 minutes.
Stretches w ere held for 30 second s at a point of mild d iscom fort, but not pain, as
acknow led ged by the participant. The first stretch for the hip extensors and knee flexors
w as the sit-and -reach in w hich participants sat on the floor, extend ed their legs and
low ered their head tow ard their knees. The second stretch, for the knee extensor
m uscles consisted of p articipants stand ing w ith one foot extend ed , w hile grasping the
heel of the opposite leg and pulling their knee joint into flexion until their heel touched
their buttocks. For the plantar flexors, subjects stood w ith one leg extend ed , and foot
flat on the ground . Follow ing, the opposite leg w as placed on a block raising the ball of
the foot above the heel. Once achieved , participants m oved forw ard until they
d eveloped m axim um tension. The fourth stretch for the hip flexors and extensors w as
the lunge. The final stretch for the gluteal m usculature involved participants crossing
one leg over the other and pulling the rear leg into their chest w hile supine on the floor.
On non-stretching d ays, participants sat quietly for 15 m inutes prior to the exercise
Preload and Perform ance Runs
Experim ents w ere perform ed after at least one w eek of recovery and follow ing a
3-hour fast. All participants perform ed the experim ental protocol on tw o separate
occasions u nd er stretching and non -stretching cond itions in a rand om ized ,
counterbalanced ord er. Participants w ore the sam e clothes and running shoes for all
sessions. The experim ental protocol consisted of a 30-m inute preload and 30-m inute
perform ance run. Participants began w ith a preload run for 30 m inutes at 65% of their
pred eterm ined VO 2m ax. Expired gases w ere collected the entire 30 m inutes u sing a
m etabolic cart system , H R w as record ed every m inute and RPE w as record ed every five
m inutes. Ru nning econom y w as d eterm ined by m easuring total kcal expend iture and
VO 2 d uring the 30-m inute preload run at each participant’ s 65% VO 2m ax value. In the
final 30 m inutes, a perform ance bout w as cond ucted w here particip ant s attem pted to
cover as m uch d istance as possible by controlling their ow n speed on the tread m ill.
During the perform ance run, the participants w ere allow ed to view the tim e d isplay,
but not the d istance covered or speed at w hich they w ere currently running. Ru nning
speed and H R w ere record ed every m inute, w hile RPE w as record ed every five
m inutes. Perform ance w as m easured as the total d istance covered d uring the final 30
m inutes. For both the preload and perform ance runs, H R and RPE w ere averaged over
each 30-m inute trial and then analyzed .
Com m itm ent Check
After com pleting the perform ance run and sit-and -reach test, participants w ere
asked to com plete a short likert-scaled m otivational assessm ent in ord er to d eterm ine
the participant’ s perception of perform ance d uring and com m itm ent to the exercise
testing session (Append ix E). After the first experim ental session, p articipants w ere
also asked if they w ere currently involved in a stretching or flexibility program , e.g.
yoga, pilates and static stretching.
Participants kept a record of their d iet (food and w ater) for 72 hours prior to the
first experim ent (Append ix F). The d iet w as then given to the participants w ith
instructions to replicate the food consum ption for 72 hours prior to the second
rand om ly assigned experim ent. After the second experim ental session, food logs w ere
collected from each participant.
Statistical analysis w as perform ed using SPSS version 15. Sam ple size estim ation
w as d eterm ined a priori as a function of the significance criterion ( ), the statistical
pow er and effect size (ES). Effect size w as calculated using the follow ing form ula:
ES = ( 1- 0)/ S0
Where 1 is the m ean of the experim ental value, 0 is the m ean of the control
value and S0 is the larger stand ard d eviation of the tw o m eans (prod ucing the m ost
conservative effect size). For this experim ent, an effect size of 0.8 w as used , based on
N elson et al. (2005) w ho exam ined strength end urance as m easured by the num ber of
repetitions perform ed using knee flexion und er stretching and non -stretching
cond itions. Using the equation ES = ( 1- 0)/ S0, the stud y had an effect size of 0.83 =
[(14.4-10.9)/ 4.2] . Statistical analysis w as set at an = 0.05, ES = 0.8 and a statistical
pow er of 0.80, w hich yield ed a m inim um of 12 subjects.
The ind epend ent variable w as stretching: use of static stretching for the
experim ental cond ition and passive sitting for the control cond ition. The null
hypothesis w as that stretching w ou ld have no effect on the d epend ent variables of
energy expend iture (VO 2 and calories), d istance covered , heart rate, and RPE d uring the
tread m ill run. Possible effects of the ind epend ent variable on the d epend ent variables
w ere evaluated statistically by a repeated m easures analysis of variance to m easure
d ifferences betw een cond itions. All significance w as accepted at p < 0.05.
CH APTER 4
Subject Data and Stretching
Fourteen trained , non-sm oking w om en, currently running at least 20 m iles a
w eek, volunteered to participate in this stud y. One participant d ropped after
d eveloping oligom enorrhea and another d ue to sched ule conflicts. The rem aining
tw elve su bjects com pleted the entire protocol (Table 1).
TABLE 1. Descriptive characteristics of the p articipants (N =12).
Variables Range Mean SD
Age (years) 23 – 47 30 9
H eight (m ) 1.43 – 1.67 1.59 0.07
Weight (kg) 40.8 – 64.0 54.8 7.2
Bod y Fat % 15.6 – 25.0 19.7 2.8
BMI (kg/ m 2) 19.1 – 23.1 21.5 1.4
VO 2m ax (m l/ kg/ m in) 36.7 – 56.1 48.4 5.1
BMI: bod y m ass ind ex; VO 2m ax: m axim al oxygen uptake
The static stretching protocol caused a significant increase in flexibility betw een
the pre- and post-stretching cond itions as m easured by the sit-and -reach test (Table 2),
29.8 8.6 vs. 33.1 8.1 cm (F(1,11) = 63.85; p < 0.05; ES = .85). There w as no d ifference in
baseline flexibility betw een the stretch and non -stretch visits. In ad d ition, w hen the
post-stretch values w ere com pared to the non -stretch baseline m easurem ents the
resulting increase in flexibility attributed to the static stretching protocol rem ained
significant (Table 2), 30.7 8.5 vs. 33.1 8.1 cm (F(1,11) = 10.72; p < 0.05; ES = .49).
TABLE 2. Acute changes in flexibility follow ing the static stretching protocol (N =12).
Cond itions Sit-and -Reach (cm )
N on-Stretch Baseline 30.7 8.5
Post-Run 31.4 7.8
Stretch Baseline 29.8 8.6
Post-Stretch 33.1 8.1*†
Post-Run 32.0 8.3
Values expressed as m ean SD
*Significantly greater than stretch baseline value (p < 0.05)
†Significantly greater than non -stretch baseline value (p < 0.05)
Preload and Perform ance Runs
There w ere no significant d ifferences betw een heart rates (157 10 vs. 160 12
bpm ) or RPEs (12 2 vs. 12 1) d uring the preload run in the non -stretched and stretched
cond itions. In ad d ition, there w ere no d ifferences in calorie expend iture (270 41 vs.
270 41 kcal) or relative VO 2 at 65% (33.7 3.1 vs. 33.8 2.3 m l/ kg/ m in) d uring the
preload run in the non-stretched and stretched cond itions (Table 3).
TABLE 3. Preload run variables (N =12).
Variables N on-Stretch Stretch
Range Mean SD Range Mean SD
H R (bpm ) 138 – 169 157 10 138 –173 160 12
RPE (Borg scale) 8 – 16 12 2 9 – 15 12 1
Calories (kcal) 202 – 348 270 41 197 – 344 270 41
65% VO 2 (ml/ kg/ m in) 28.6 – 37.3 33.7 3.1 29.2 – 37.6 33.8 2.3
H R: heart rate; RPE: rating of perceived exertion; VO 2: oxygen uptake
Table 4 presents the perform ance run d ata of the participants. During the
perform ance run, the variation in d istance covered d uring th e exercise protocol ranged
from a m inim um run of 4.67km to a m axim um perform ance run of 6.82km . There w ere
no significant d ifferences in total d istance covered d uring the perform ance run in the
non-stretched and stretched cond itions (5.53 0.60 vs. 5.52 0.69 km ). As w ould then be
expected , there w ere no d ifferences in running speed d uring the perform ance run und er
the non-stretched and stretched cond itions (11.1 1.2 vs. 11.1 1.4 km / h). There w ere
also no significant d ifferences in heart rates (187 8 vs. 188 7 bp m ) or RPEs (18 2 vs.
18 1) in the non-stretched and stretched cond itions at the end of the 30-m inute run, nor
w ere there d ifferences in the average heart rates (175 9 vs. 177 6 bp m ) and RPEs (16 1
vs. 16 1) d uring the 30-m inute perform ance run in th e non-stretched and stretched
TABLE 4. Perform ance run variables (N =12).
Variables N on-Stretch Stretch
Range Mean SD Range Mean SD
Distance (km ) 4.80 – 6.55 5.53 0.60 4.67 – 6.82 5.52 0.69
Speed (km / h) 9.7 – 13.2 11.1 1.2 9.4 – 13.7 11.1 1.4
H Rm ax (bp m ) 174 – 195 187 8 178 – 197 188 7
RPEm ax (Borg scale) 14 – 20 18 2 16 – 20 18 1
H R (bpm ) 161 – 189 175 9 168 – 187 177 6
RPE (Borg scale) 13 – 18 16 1 15 – 17 16 1
H Rpeak : heart rate at end of perform ance run ; RPEpeak : rating of perceived exertion at
end of perform ance run; H R: heart rate; RPE: rating of perceived exertion
Com m itm ent Check
After com pletion of the exercise protocol, participants com pleted a short
m otivational assessm ent and stretch history (Append ix E). The resp onses w ere scored
from 1-none/ not at all to 5-very m uch/ very w ell on three d ifferent perception
questions. There w as no significant d ifference betw een scores in the non -stretched and
stretched cond ition (Table 5), 14 1 vs. 14 1, respectively. From the stretch history
question it w as d eterm ined that five out of the 12 participants w ere habitual stretchers.
For those five, the typical routine consisted of static stretches like those used in our
TABLE 5. Post-run participant com m itm ent d ata (N =12).
Participant ID N on-Stretch Stretch
1 14 14
2 15 15
3 11 12
4 15 15
5 13 13
6 15 15
7 14 13
8 15 15
9 15 15
10 15 15
11 15 15
12 14 14
CH APTER 5
The purpose of this stu d y w as to com pare the effects of a static stretching
protocol on running econom y and d istance p erform ance. The m ain find ings of this
stud y w ere that static stretching increased flexibility, as m easured by the sit and reach
test, but the increased range of motion experienced by the fem ale ru nners d id not have
any effect on running econom y or d istance perform ance. These find ings are contrary to
a com parable stud y perform ed in our laboratory that found a significant d ecrease in
running econom y and d istance perform ance in m ale runners (u npublished ) .
Stud ies have show n a positive relationship betw een stiffness and running
econom y [31, 37]. Aram patzis, et al found that the m ost econom ical runners w ere those
w ith the highest m easures of triceps surae stiffness, 34.4 kN m easured d uring ankle
plantarflexion MVC, w hen com pared to runners w ith sim ilar VO 2m ax values .
These results are supp orted by Craib and colleagues, w ho show ed that m easures of
d orsiflexion flexibility w ere positively and significantly correlated w ith subm axim al
VO 2 (r=0.65). The resu lts of Craib’ s stud y found that 47% of the variation in running
econom y could be explained by the variation in stand ing external hip rotation and
d orsiflexion .
Dalleau, et al found an inverse relationship betw een stiffness and m etabolic
energy cost at a given velocity; w hen running at 90% VO 2m ax, greater leg stiffness w as
correlated w ith low er energy cost of running . These results su pport speculations
from Craib et al that running econom y at higher velocities m ay be m ore affected by
stiffness than those at the m od erate velocities tested , e.g. 65% VO 2m ax. At higher
speed s, low er bod y flexibility m ay d ecrease the am ount of elastic energy storage and
lead to ad d itional m uscle activity in an attem pt to stabilize the bod y d uring running
It should be noted that each of the referenced stud ies u sed m ale runners and
previous w ork has show n significant gend er d ifferences in the viscoelastic properties of
the MTU betw een m en and w om en [38, 48, 49]. In a stud y by Granata et al, they used a
tw o-legged hopping task on a force platform to m easure active m uscle stiffness .
Subjects perform ed thirty hops at three d ifferent frequencies, 2.5 H z, 3.0 H z and at the
subject’ s self-selected frequency. Mean leg stiffness values w ere alm ost 29% greater in
m ales (33.9 8.7 kN / m ) than in fem ales (26.3 6.5 kN / m ), w ith significant d ifferences
at each of the hopping frequencies . If MTU stiffness plays a m ajor role in
perform ance d u ring running, this m ay help explain w hy our w om en runners d id not
have the sam e response to the stretching protocol as the previously tested m en.
In our stud y, sit and reach test results w ere u sed as the d eterm inant of low er
bod y flexibility. H ow ever, th e sit and reach test has contrad ictory results in
correlational stud ies. Craib et al found no significant correlation betw een sit and reach
results and running econom y at 68% VO 2m ax w hereas Trehearn and Buresh found a
significant relationship (r=0.826) betw een sit and reach scores and ru nning econom y at
60% VO 2m ax [55, 56]. It is possible that the 12% increase in flexibility follow ing the
static stretching protocol w as not representative of a true overall d ecrease in stiffness
and therefore had no affect on running econom y d uring our 65% VO 2m ax run. These
results are in line w ith the find ings of H ayes and Walker w ho found no d ifference in
running econom y d uring a subm axim al tread m ill run w ith velocity set at 50% ∆below
lactate threshold , w here ∆is the d ifference betw een VO 2 at lactate threshold and
VO 2m ax, follow ing a static stretching protocol . Although running econom y w as
not m easured d uring the final 30-m inute portion of our tread m ill protocol, participants
ran at 94% H Rm ax, even at the faster speed s there w as no d ifference in H R betw een the
non-stretched , presum ably stiffer, and the stretched cond ition.
The only other stud y to look at the effects of static stretching on d istance
perform ance w as perform ed in our laboratory by Wilson and colleagues (unp ublished ).
Distance perform ance d uring a 30-m inute tim e trial run on a treadm ill d ecreased
significantly in trained m ale runners follow ing stretching . When the sam e protocol
w as utilized to test trained fem ale runners, w e found no significant d ifference betw een
the non-stretched and stretched cond itions, 5.53 .60 vs. 5.52 .69 km , respectively.
Stud ies investigating the effects of static stretching on m uscular pow er and
strength in w om en have show n d ecreases in perform ance sim ilar to that of men [11, 58,
59]. In a stud y by Bacurau et al, follow ing tw o sets of six static stretches held for 30
second s each, leg press strength d eclined by 13.4% w hen com pared to the contro l
cond ition. This d rop in perform ance w as associated w ith a 12% increase in flexibility as
d eterm ined by the sit-and -reach test, alm ost id entical to the increase in flexibility
m easured in our stud y . In regard s to pow er, static stretching has been show n to
d ecrease sprint and vertical jum p height [11, 59]. Wallm an and colleagues found that
three 30-second static stretches of the gastrocnem ius w ere not only associated w ith a
5.6% d ecline in vertical jum p perform ance, bu t also a 17.9% increase in EMG activity.
They proposed the increase in m otor unit activation w as required to com pensate for the
increased m u scle com pliance and d ecreased efficiency .
Although w om en appear to follow the sam e trend as m en, d ecreased
perform ance w ith increased flexibility, there is conflicting evid ence in the stud y of
running econom y [56, 60]. When investigating the relationship betw een low er lim b and
trunk flexibility and running econom y in fem ale track athletes, Beaud oin et al. found no
relationship . These find ings are contrary to the popular belief that MTU stiffness
significantly contributes to changes in perform ance follow ing static stretching.
H ow ever, in a stud y w ith w om en collegiate d istance runners, Trehearn and Buresh
found that the m ost econom ical runners w ere the least flexible .
In a stud y by Daniels and Daniels, they found m en to be m ore econom ical than
w om en, even w hen m atched w ith their VO 2m ax w om en partners . In ad d ition,
investigators found that the speed ran d uring the econom y m easurem ents significantly
im pacted w hich type of runner w as m ost econom ical. The runners w ere separated into
short d istance (.8-1.5k), m ed ium d istance (3-5k) and long d istance (m arathon) athletes.
When the speed of the econom y trials w as set at race pace or faster, the short d istance
athletes w ere m ost econom ical. H ow ever, w hen the speed tested w as slow er than race
pace, the long d istance athletes w ere m ost econom ical .
The results of our stud y suggest that static stretching prior to long distance
end urance activities increases low er bod y flexibility, but has no im pact on running
econom y or d istance perform ance in trained fem ale runners. It is possible that
variability in the type of end urance athlete, 10k versus m ar athon, led to increased
variability in our m easures of perform ance. If this w ere the case, the 65% intensity run
m ay have cau sed d ifferences in econom y not associated w ith any effect of the static
stretching, this could also explain part of the gend er d ifference reported in our stud y. If
our w om en consisted of both 10k and m arathon specialists and the m en’ s stud y w ere a
hom ogeneous group of d istance specialists, this could lead to d ifferent responses to the
static stretching protocol.
It is also possible that the w om en athletes in our stud y w ere not as aerobically
trained as their m ale counterparts. Although a VO 2m ax of 48.4 5.1 m l/ kg/ m in place
our athletes w ell above the highest fitness category for their age group, relatively
speaking they m ay not have been as w ell trained as the m en. This d ifference in training
level could have led to increased variability betw een exercise testing sessions. When
com bined w ith the extend ed tim e period s required betw een visits, 3-4 w eeks in w om en
vs. 1 w eek in m en, the variability in perform ance m ay have m asked any possible effects
of the static stretching protocol.
It should also be noted that w e d id not control w hether our participants w ere
habitual stretchers. Five of the 12 participants involved in our stud y engag ed in chronic
stretching regim ens. The variability of group d ynam ic m ay have affected the
m agnitud e of change associated w ith the static stretching protocol.
The proposed m echanism s associated w ith d eclines in perform ance, d ecreased
neural activation and MTU stiffness, m ay not hold true for fem ale athletes. Whether
this is related to the ind ivid ual’ s absolute stiffness levels, a gend er threshold of relative
d ecline in stiffness or related to som ething else entirely is unknow n. Further research,
utilizing d ifferent m easures of flexibility and stiffness, should be perform ed in larger
sam ple sizes of trained m ale and fem ale runners to d eterm ine if the gend er d ifference
continues to have a sim ilar effect on flexibility and perform ance before fem ale d istance
runners are prescribed static stretching protocols prior to d istance events.
APPEN DIX A
RECRUITMEN T FLYER
APPEN DIX B
H EALTH H ISTORY QUESTION N AIRE
1. H as your d octor ever said that you have a heart cond ition and that you should only
d o physical activity recom m end ed by a d octor?
2. Do you feel pain in your chest w hen you d o physical exertion?
3. In the past m onth, have you had chest pain w hen you w ere not d oing physical
4. Do you lose your balance because of d izziness or d o you ever lose consciousness?
5. Do you have a bone or joint problem (for exam ple, back, knee or hip) that could be
m ad e w orse by a change in your physical activity?
6. Is your d octor currently prescribing d rugs (for exam ple, w ater pills) fo r your blood
pressure or heart cond ition?
7. Do you know of any other reason w hy you should not d o physical activity?
8. At w hat age d id you have your first m enstrual period ?
9. H ave you had m enstrual period s w ithin the past 12 m onths?
If yes, how m any? ____ When w as your m ost recent m enstrual period ? ________
H ow m uch tim e d o you usually have from the start of one period to the start of
What w as the longest tim e betw een m enstrual period s w ithin the past year? ____
10. Do you have painful or heavy m enstrual period s? _________
11. Do you take any med ications d uring your m enstrual period s? If yes, w hat? ________
12. Do you take birth control pills? If yes, w hat brand ? ___________________________
13. H ave you had a pelvic exam ination w ithin the last year?
14. Please list all m ed ications that you are currently taking. Please includ e vitam ins or
15. Do you run at least 20 m iles a w eek, and have previously com peted in long d istance
running events (10K or longer)?
APPEN DIX C
IN FORMED CON SEN T FORM
1. I freely and voluntarily and w ithout elem ent of force or coercion, consent to be a
participant in the research project entitled “ The effects of static stretching on
running econom y and end urance perform ance in fem ale d istance ru nners d uring
tread m ill running.” Chris Mojock and Lynn Panton, PhD., a stud ent and a
faculty m em ber, respectively, at Florid a State University in the Departm ent of
N utrition, Food and Exercise Sciences are cond ucting this research.
2. The purpose of the research project is to evaluate the effects of static stretching
on end urance perform ance on a tread m ill in trained w om en runners. Tw elve
trained w om en 18-45 years of age w ill be recruited for this stud y.
3. My participation in this project w ill require m y attend ance at the Florid a State
University Exercise Physiology Laboratory on four d ifferent d ays to com plete the
experim ental protocol d escribed below .
On the first d ay of the stud y I w ill com e to the Exercise Physiology Laboratory
after a 3-hour fast to sign an inform ed consent, and to answ er questions on m y
m ed ical and m enstrual cycle history. I w ill also have m y blood pressure
m easured . If I have high blood pressure (greater than 140/ 90 m m H g), or have
any contraind ications to tread m ill run testing I w ill not be able to participate in
the stud y. If I am not m enstruating I w ill also not be able to participate in the
stud y. After com pleting the questionnaires I w ill have m y m axim al oxygen
consum ption (VO 2m ax) tested using a progressive tread m ill exer cise test to
exhaustion protocol. I w ill begin the test at a speed of 10 km h -1 and a 1% incline.
Every m inute the treadm ill speed w ill be increased by 2km / h until I can no
longer m aintain the pace. During the test I w ill w ear head gear w ith a
m outhpiece attached , a nose clip, and a heart rate m onitor around m y chest. On
the second visit I w ill participate in a fam iliarization 60 m inute perform ance run
on a tread m ill. During this tim e I w ill run at m od erate intensity (65 % V02 max)
for 30 m inutes, follow ed by a 30-m inute perform ance run w here I w ill attem pt to
cover as m uch d istance as possible by controlling the speed of the tread m ill
w ithout being able to view the d istance covered or current speed . Follow ing the
run I w ill be fam iliarized w ith 3 stretching exercises for m y low er back, front and
back thighs, and calves. On the third and fourth visits I w ill com e to the Exercise
Physiology Laboratory after a 3-hour fast and w ill be rand om ly assigned to
either perform 15 m inutes of stretching using the 3 previous d em onstrated
stretches, or sit quietly for 15 m inutes. After the 15 m inutes have passed , I w ill
perform the sam e 60-m inute perform ance run on the tread m ill that I learned on
d ay 2. These tw o visits w ill be perform ed d u ring tw o follicular phases (d uring
m enstruation) of my m enstrual cycle. The test w ill be separated by at least 21
I w ill be instructed to consum e m y norm al d iet as w ell as keep d aily activity to a
m inim u m for 72 hours prior to each testing period . In ad d ition I w ill be given a
log to record m y d iet for 72 hours before and d uring the testing period on visit
three. I w ill then be asked to consum e an id entical d iet for the fourth testing
period . For all visits to the lab I w ill w ear the sam e clothes and running shoes.
4. I und erstand there is a possibility of a m inim al level of risk involved if I agree to
participate in this stud y. The risks w ill be m inim ized by using trained
technicians and by teaching m e proper techniques in u sing the tread m ill and
stretching. I w ill com p lete a m ed ical history before I can participate in the stud y
and I w ill have m y blood pressure m easured . If I have high blood pressure
(greater than 140/ 90 m m H g) or have any contraind ications to treadm ill run
testing or do not have a m enstrual cycle I w ill not be able to participate in the
stud y. All m outh pieces, breathing hoses, and nose clips w ill be sterilized and
cleaned w ith d isinfecting solutions.
5. The results of this research stud y m ay be published but m y nam e or id entity w ill
not be revealed . Inform ation obtained d uring the course of the stud y w ill rem ain
confid ential, to the extent allow ed by law . My nam e w ill not appear on any of
the results. N o ind ivid ual responses w ill be reported . Only group find ings w ill
be reported in publications. Con fid entially w ill be m aintained by assigning each
subject a cod e num ber and record ing all d ata by a cod e num ber. The only record
w ith the subject’ s nam e and cod e num ber w ill be kept by Dr. Lynn Panton, in a
locked d raw er in her office. This record w ill be d estroyed in 10 years.
6. In case of injury, the laboratory personnel w orking on the research project w ill
provid e first aid ; any other treatm ent or care w ill be provid ed at m y expense.
7. I w ill not be paid for m y participation in this research project.
8. Any questions I have concerning the research stud y or m y participation in it,
before or after m y consent, w ill be answ ered by the investigators or they w ill
refer m e to a know led geable source. I und erstand that I m ay contact Chris
Mojock, cd m email@example.com u , (850) 445-9153 or Dr. Lynn Panton (850) 644-4685,
lpanton@m ailer.fsu.ed u , for answ ers to questions about this research project or
m y rights. Group results w ill be sent to m e upon m y request.
9. In case of injury, or if I have questions about m y rights as a subject/ participant in
this research, or if I feel I have been placed at risk, I can contact the chair of the
H um an Subjects com m ittee, Institutional Review Board , th rough the Office of the
Vice Presid ent for Research, at (850) 644-8633.
10. Benefits from this stud y includ e learning if stretching prior to an end urance
event is beneficial or harm ful to perform ance.
11. The nature, d em and s, benefits and risks of the project have been explained to
m e. I know ingly assu m e any risks involved .
I have read the above inform ed consent form . I und erstand that I m ay w ithd raw m y
consent and d iscontinue participation at any tim e w ithout penalty or loss of benefits
to w hich I m ay otherw ise be entitled . In signing this consent form , I am not w aiving
m y legal claim s, rights or rem ed ies. A copy of this consent form w ill be given to m e.
(Su bject) (Date)
APPEN DIX D
IRB APPROVAL LETTER
APPEN DIX E
COMMITMEN T CH ECK
Stretching and Perform ance
H ow w ill stretching effect your perform ance? (place a check m ark next to your answ er)
1. It w ill increase it _____
2. It w ill have no effect _____
3. It w ill d ecrease it _____
Do you regularly stretch? (Y/ N )
If yes, how often, w hat type and for how long?
CO MMITMENT CHECK
Thank you for participating in the exercise task. Please answ er the follow ing questions
as honestly as you can.
1. How committed w ere you to the task w hile performing?
1 2 3 4 5
none/ not at all very m uch/ very w ell
2. How w ell do you think you tolerated the effort associated w ith the task?
1 2 3 4 5
none/ not at all very m uch/ very w ell
3. How much effort did you invest in the task?
1 2 3 4 5
none/ not at all very m uch/ very w ell
APPEN DIX F
DIETARY RECORD IN STRUCTION S
1. Use the Dietary Record Form s provid ed to record everything you eat or drink for
3 consecutive d ays – tw o w eekd ays and one w eekend d ay.
2. Ind icate the nam e of the FOOD ITEM, the AMOUN T eaten, how it w as
PREPARED (fried , boiled , etc.), and the TIME the food w as eaten. If the item
w as a brand nam e prod uct, please includ e the nam e. Try to be accu rate about
the am ounts eaten. Measuring w ith m easuring cups and spoons is best, but if
you m ust m ake estim ates, use th e follow ing guid elines:
Fist is about 1 cup
Tip of Thu m b is about 1 teaspoon
Palm of the hand is about 3 ounces of meat (about the size of a d eck of
Tip of Thu m b is about 1 ounce of cheese
3. Try to eat w hat you norm ally eat and record everything. The project w ill only be
useful if you are H ON EST about w hat you eat. The inform ation you provid e is
4. MILK: Ind icate w hether m ilk is w hole, low fat (1 or 2%), or skim . Includ e
flavoring if one is used .
5. VEGETABLES and FRUITS: One average serving of cooked or canned fruits and
vegetables is about a half cup. Fresh w hole fruits and vegetables should be listed
as sm all, m ed ium , or large. Be sure to ind icate if sugar or syrup is ad d ed to fruit
and list if any m argarine, butter, cheese sauce, or cream sauce is ad d ed to
vegetables. When record ing salad , list item s com prising the salad separately and
be sure to includ e salad d ressing used .
6. EGGS: Ind icate m ethod of preparation (scram bled , fried , poaches, etc.) and
num ber eaten.
7. MEAT / POULTRY / FISH : Ind icate approxim ate size or w eight in ounces of
the serving. Be sure to includ e any gravy, sauce, or bread ing ad d ed .
8. CH EESE: Ind icate kind , num ber of ounces or slices, and w hether it is m ad e from
w hole m ilk, part skim , or is low calorie.
9. CEREAL: Specify kind , w hether cooked or d ry, and m easure in term s or cups or
ounces. Rem em ber that consum ing 8 oz. of cereal is not the sam e as consum ing
one cup of cereal. 1 cu p of cereal generally weighs about 1 ounce.
10. BREAD and ROLLS: Specify kind (w hole w heat, enriched w heat, rye, etc.) and
num ber of slices.
11. BEVERAGES: Includ e every item you d rink exclud ing w ater. Be sure to record
cream and sugar used in tea and coffee, w hether juices are sw eetened or
unsw eetened and w hether soft d rinks are d iet or regular.
12. FATS: Rem em ber to record all butter, m argarine, oil, and other fats used in
cooking or on food .
13. MIXED DISH ES / CASSEROLES: List the m ain ingred ients and ap proxim ate
am ount of each ingred ient to the best of your ability.
14. ALCOH OL: Be honest. Record am ounts in ounces. Specify w ith “ light” or
“ regular” beer.
DIETARY RECORD FORM
Day of the Week: _________________
FOOD ITEM AMOUN T TIME
Express approxim ate m easures in cups (C), tablespoons (T), teaspoons (t), gram s
(g), ounces (oz.), pieces, etc.
1. Behm DG and Kibele A. Effects of differing intensities of static stretching on jump
performance. Eur J Appl Physiol, 2007. 101: p. 587-594.
2. Cornw ell A, N elson AG and Sid aw ay B. A cute effects of stretching on the
neuromechanical properties of the triceps surae muscle complex. Eur J Appl Physiol,
2002. 86: p. 428-434.
3. Knud son D, Bennett K, Corn R, Leick D and Sm ith C. A cute effects of stretching are
not evident in the kinematics of the vertical jump. J Strength Cond Res, 2001. 15(8): p.
4. Pow er K, Behm D, Cahill F, Carroll M and Young W. A n acute bout of static
stretching: effects on force and jumping performance. . Med Sci Sports Exerc, 2004.
36(8): p. 1389-1396.
5. Unick J, Kieffer H S, Cheesm an W and Feeney A. The acute effects of static and
ballistic stretching on vertical jump performance in trained women. J Strength Cond
Res, 2005. 19(1): p. 206-212.
6. Young W and Elliot S. A cute effects of static stretching, proprioceptive neuromuscular
facilitation stretching and maximum voluntary contractions on explosive force
production and jumping performance. Res Q Exerc Sports, 2001. 3: p. 273-279.
7. Young WB and Behm DG. Effects of running, static stretching and practice jumps on
explosive force production and jumping performance. J Sports Med Phys Fitness, 2002.
34: p. 119-124.
8. Knud son D and N offal G. Time course of stretch-induced isometric strength deficits.
Eur J Appl Physiol, 2005. 94: p. 348-351.
9. Kokkonen J, N elson AG and Cornw all A. A cute muscle stretching inhibits maximal
strength performance. Res Q Exerc Sports, 1998. 4: p. 411-415.
10. Fletcher IM and Jones B. The effect of different warm-up stretch protocols on 20 meter
sprint performance in trained rugby union players. J Strength Cond Res, 2004. 18(4):
11. Fletcher IM and Anness R. The acute effects of combined static and dynamic stretch
protocols on fifty-meter sprint performance in track-and-field athletes. J Strength Cond
Res, 2007. 21(3): p. 784-787.
12. H albertsm a JP, van Bolhuis AI and Goeken LN . Sport stretching: effect on passive
muscle stiffness of short hamstrings. Arch Phy Med Rehab, 1996. 77: p. 688-692.
13. Magnusson SP, Aagaard P and N ielson JJ. Passive energy return after repeated
stretches of the hamstring muscle-tendon unit. Med Sci Sports Exerc, 2000. 33: p.
14. Beed le BB and Mann CL. A comparison of two warm-ups on joint range of motion. J
Strength Cond Res, 2007. 21(3): p. 776-779.
15. Shrier I. Stretching before exercise does not reduce the risk of local muscle injury: a
critical review of the clinical and basic science literature. Clin J Sport Med, 1999. 9: p.
16. Ingen Schenau GJ. A n alternative view of the concept of utilization of elastic energy in
human movement. H um Mov Sci, 1984. 3: p. 301-336.
17. Kubo K, Kanehisa H , Kaw akam i Y and Fukunaga T. Influence of static stretching
on viscoelastic properties of human tendon structures in vivo. J Appl Physiol, 2001. 90:
18. Kubo K, Morim oto M, Kom uro T, Tsunod a N , Kanehisa H and Fuku naga T.
Influences of tendon stiffness, joint stiffness, and electromyographic activity on jump
performances using single joint. Eur J Appl Physiol, 2007. 99: p. 235-243.
19. Rosenbaum D and H ennig EM. The influence of stretching and warm-up exercises on
achilles tendon reflex activity. J Sport Sci, 1995. 13: p. 481-490.
20. Shorten MR. M uscle elasticity and human performance. Med Sports Sci, 1987. 25: p.
21. Wilson GJ, Murphy AJ and Pryor JF. M usculotendinous stiffness: its relationship to
eccentric, isometric and concentric performance. J Appl Physiol, 1994. 76: p. 2714-
22. Moore JC. The golgi tendon organ: a review and update. Am J Occup Ther, 1984. 38:
23. Belli A and Bosco C. Influence of stretch-shortening cycle on mechanical behaviours of
triceps surae during hopping. Acta Physiol Scand , 1992. 144: p. 401-408.
24. Davis DS, Ashby PE, McCale KL, McQuain JA and Wine JM. The effectiveness of 3
stretching techniques on hamstring flexibility using consistent stretching parameters. J
Strength Cond Res, 2005. 19(1): p. 27-32.
25. Knud son D. Stretching during warm-up: do we have enough evidence? J Orthop
Sports Phys Ther, 1999. 70: p. 24-27, 51.
26. Mad d ing SW, Wong JG, H allum A and Med eiros J. Effect of duration of passive
stretch on hip abduction range of motion. J Orthop Sports Phys Ther, 1987. 8: p. 409-
27. N elson AG, Kokkonen J and Arnall DA. A cute muscle stretching inhibits muscle
strength endurance performance. J Strength Cond Res, 2005. 19(2): p. 338-343.
28. Bassett DR and H ow ley ET. Limiting factors for maximum oxygen uptake and
determinants of endurance performance. Med Sci Sports Exerc, 2000. 32(1): p. 70-84.
29. Pram pero PE. Factors limiting maximal performance in humans. Eur J Appl Physiol,
2003. 90: p. 420-429.
30. Baba R, N agashim a M, Goto M, N agano Y, Yokota M, Tauchi N and N ishibata K.
Oxygen uptake efficiency slope: A new index of cardiorespiratory functional reserve
derived from the relation between oxygen uptake and minute ventilation during
incremental exercise. JACC, 1996. 28(6): p. 1567-72.
31. Aram patzis A, De Monte G, Karam anid is K, Morey-Klapsing G, Stafilid is S and
Bruggem ann GP. Influence of the muscle-tendon unit' s mechanical and morphological
properties on running economy. J Exp Biol, 2006. 209: p. 3345-3357.
32. H eise GD and Martin PE. Leg spring characteristics and the aerobic demand of
running. Med Sci Sports Exerc, 1998. 30(5): p. 750-754.
33. Taylor CR. Relating mechanics and energetics during exercise. Ad v Vet Sci, 1994.
38(A): p. 181-215.
34. McMahon TA, Valiant G and Fred erick EC. Groucho Running. J Appl Physiol,
1987. 62: p. 2326-2337.
35. Dutto DJ and Sm ith GA. Changes in spring-mass characteristics during treadmill
running to exhaustion. Med Sci Sports Exerc, 2002. 34(8): p. 1324-1331.
36. Wilson JM, H ornbuckle L, Kim JS, Lee SR, Som m er B and Panton LB. The effects of
static stretching on energy cost and endurance performance during a 60-minute time
trial in trained male distance runners. 2007, Florid a State University: Tallahassee.
37. Dalleau G, Belli A, Bourd in M and Lacour JR. The spring-mass model and the energy
cost of treadmill running. Eur J Appl Physiol, 1998. 77: p. 257-263.
38. Wojtys EM, H uston LJ, Schock H J, Boylan JP and Ashton -Miller JA. Gender
differences in muscular protection of the knee in torsion in size-matched athletes. J Bone
Joint Surg Am , 2003. 85: p. 782-789.
39. Avela J, Kyrolainen H and Kom i PV. A ltered reflex sensitivity after repeated and
prolonged passive muscle stretching. J App Physiol, 1999. 86: p. 1283-1291.
40. Cram er JT, H oush TJ, Weir JP, Johnson GO, Coburn JW and Beck TW. The acute
effects of static stretching on peak torque, mean power output, electromyography, and
mechanomyography. Eur J Appl Physiol, 2005. 93: p. 530-539.
41. Marek SM, Cram er JT, Fincher AL, Massey LL, Dangelm aier SM, Purkayastha S,
Fitz KA and Culbertson JY. A cute effects of static and proprioceptive neuromuscular
facilitation stretching on muscle strength and power output. J Athletic Training, 2005.
40(2): p. 94-103.
42. Brooks GA, Fahey TD and Bald w in KM. Exercise Physiology: Human Bioenergetics
and Its A pplications. 4th ed . 2005, Boston: McGraw -H ill. 876.
43. Dean TM, Perreault L, Mazzeo RS and H orton TJ. N o effect of menstrual cycle phase
on lactate threshold. J App Physiol, 2003. 95: p. 2537-2543.
44. Kolka MA and Stephenson LA. Effect of luteal phase elevation in core temperature on
forearm blood flow during exercise. J App Physiol, 1997. 82(4): p. 1079-1083.
45. Pivarnik JM, Marichal CJ, Spillm an T and Morrow , Jr JR. M enstrual cycle affects
temperature regulation during endurance exercise. J App Physiol, 1992. 72(2): p. 543-
46. Janse d e Jonge XAK. Effects of the menstrual cycle on exercise performance. Sports
Med , 2003. 33(11): p. 833-851.
47. H all Jurkow ski JE, Jones N L, Toew s CJ and Sutton JR. Effects of menstrual cycle on
blood lactate, O2 delivery and performance during exercise. J App Physiol, 1981. 51(6):
48. Granata KP, Pad ua DA and Wilson SE. Gender differences in active musculoskeletal
stiffness. Part II. Quantification of leg stiffness during functional hopping tasks. J
Electrom yography Kinesiology, 2002. 12: p. 127-135.
49. Kubo K, Kanehisa H and Fukunaga T. Gender differences in the viscoelastic
properties of tendon structures. Eur J Appl Physiol, 2003. 88: p. 520-526.
50. Jackson AS and Pollock ML. Practical assessment of body composition. Phys Sport
Med , 1985. 13(3): p. 76-90.
51. Siri WE. Body composition from fluid spaces and density: analysis of methods. , in
Techniques for measuring body composition, J. Brozek, and H enschel, A., Ed itor.
1961, N atl Acad Sci: Washington, DC. p. 223-244.
52. McArd le WD, Katch FI and Katch VL. Exercise physiology: energy, nutrition and
human performance. 6th ed . 2007, Baltim ore: Lipincott William s and Wilkins.
53. Paavolainen, L., et al, Explosive-strength training improves 5-km running time by
improving running economy and muscle power. J App Physiol, 1999. 86(5): p. 1527-
54. H ow ley, E.T., et al, Criteria for maximal oxygen uptake: review and commentary. Med
Sci Sport Exerc, 1995. 27(9): p. 1292-1301.
55. Craib, M.W., Mitchell, V.A., Field s, K.B., Cooper, T.R., H opew ell, R., Morgan,
D.W., The association between flexibility and running economy in sub-elite male
distance runners. Med Sci Sport Exerc, 1996. 28(6): p. 737-743.
56. Trehearn TL and Buresh RJ. Sit-and-reach flexibility and running economy of men and
women collegiate distance runners. J Strength Cond Res, 2009. 23(1): p. 158-162.
57. H ayes PR and Walker A. Pre-exercise stretching does not impact upon running
economy. J Strength Cond Res, 2007. 21(4): p. 1227-1232.
58. Bacurau RFP, Monteiro GA, Ugrinow itsch C, Tricoli V, Cabral LF and Aoki MS.
A cute effect of a ballistic and a static stretching exercise bout on flexibility and maximal
strength. J Strength Cond Res, 2009. 23(1): p. xxx-xxx.
59. Wallm ann H W, Mercer JA and McWhorter JW. Surface electromyographic
assessment of the effect of static stretching of the gastrocnemius on vertical jump
performance. J Strength Cond Res, 2005. 19(3): p. 684-688.
60. Beaud oin CM and Whatley Blum J. Flexibility and running economy in female
collegiate track athletes. J Sports Med Phys Fitness, 2005. 45(3): p. 295-300.
61. Daniels J and Daniels N . Running economy of elite male and elite female runners. Med
Sci Sport Exerc, 1992. 24(4): p. 483-489.
BIOGRAPH ICAL SKETCH
In the spring of 2002, Christopher D. Mojock com pleted his Bachelors d egree in
Marketing at Florid a State University. Und er the ad visem ent of Prof. Lynn B. Panton,
he w ill obtain his Master’ s d egree in Exercise Physiology spring of 2009, from the
Departm ent of N utrition, Food and Exercise Sciences at Florid a State University. H e
w ill begin the Exercise Physiology d octoral program at Flo rid a State University in the
sum m er of 2009. Chris’ research interests are in the field of hum an perform ance.