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					  Exercise

Dr Reed A Berger
      Human beings have evolved with movement as a necessity for survival
              e.g. to obtain food, to escape predators
      thus, numerous systems in the body are sensitive to movement.



             Today, why do people exercise?



Athletic/Artistic Performance    Physical appearance



  How can we increase exercise for health reasons?         Health
         education - require PE for schools?
         support - physicians, family
         research
        Benefits of Exercise
 Increased strength and muscular
  endurance
 Increased BMD—osteoporosis
 Aging—decreased falls, increased
  independence, increased ADL
 Increased BMR—LBM
 Appearance, self esteem
 Technology—fewer demands placed on
  musculoskeletal and CV systems
 2-3 generations ago—manual labor
 Stairs, elevators, cars
 Recreation—playing ball, jumping, hide-n-
  seek vs. video games, internet
 Convenience and fast foods
 Automation—decreased muscular
  demands
 Body adapts—increased fast, weaker
 Scheduled exercise used to not be needed
  with manual labor
 Today, have to “give back” the leisure time
  gained thru technology and purposely
  stress the muscular system
        I. Basics of Exercise Physiology
          Exercise is a complex molecular, cellular and systemic
                          physiological stimulus

With every single bout of exercise, skeletal muscles, heart, brain, vascular
tissue, bone, liver, etc. experience some form of environmental “stress”.
  The type and magnitude of an adaptation or response to exercise thus
         results from a sum total of all these contributing factors.
                           Some examples include:

                      - mechanical, stress/strain
                      - temperature
                      - pH
                      - redox state
                      - free radical production
                      - hormones/growth factors
                      - calcium
Specificity of Exercise: Adaptations that occur in response to
  training are specific to the nature of the training stimulus

        Cardiovascular fitness: requires that the person
        train in a manner that challenges heart rate, cardiac
        output, capillarity … with the underlying change being
        improved oxygen delivery to working tissues

        Muscular strength: requires that the person train in a manner
        that challenges the recruitment and force output of specific
        muscle groups … with the underlying change being increased
        muscle mass.

       The corollary to this is that training for endurance will not
       augment strength or vice versa.
       Cardiovascular fitness - endurance type activities: fuel challenging
               large muscle mass
               repetitive
               lower intensity
               walking, running, swimming, cycling




       Muscular strength: high resistance, high force output
               focus on muscle groups not on systemic “exercise”
                        e.g. knee extensors vs. flexors

Can a type of exercise be both strength and endurance?
        yes BUT the effectiveness of any one form of activity to elicit
        a specific adaptation is dependent on the endurance/strength starting
        state of the individual.
   Basic Principles of Exercise Training
    Frequency - how often is the exercise performed
    each week? For cardiovascular training effects
    3-4x per week is suggested

Intensity - the exercise must be performed at a level that
challenges the cell/tissue/system for adaptations to occur.
Totally dependent on starting state. Lower the starting fitness
level the lower the starting intensity. Must build to continue
adaptations. Most important variable in training regimen for most.

Duration - length of each training session. For cardiovascular
Adaptations it is suggested to start at 30 minutes/session

        MORE IS NOT NECESSARILY BETTER!
              overtraining/system failure
      Known adaptations to endurance exercise


   Skeletal Muscle                   Heart
    mitochondria                     heart volume
    capillary density                max stroke volume
    oxidative enzymes                max cardiac output
                                      resting heart rate
                                      blood pressure


Brain (very new studies)                Bone
 neurogenesis                           density? Type of exercise
 protection from seizures, injury
 What is Maximum Oxygen Uptake?
 VO2 Max


Maximal amount of oxygen consumption per minute

The more muscle used the higher the oxygen use

Predictor of performance?

Correlates with changes in cardiac output

Training will result in an increase
        cardiac indices (CO, SV)
        skeletal muscle contribution (mito)
        ventilatory contribution?
   Known adaptations to resistance exercise



Brain/Neural                         Skeletal Muscle
 improved recruitment                Fiber size
                                      Mitochondria?

                         Bone
                          density
    Role of exercise in weight and/or body fat control
                   Calories in vs. Calories out
    Exercise can increase caloric expenditure

    Exercise can spare loss of lean body mass during
            times of caloric deficit

    Increases in lean body mass will increase basal metabolic rate
    BUT …. 10lbs of lean body mass will lead to about 70-80kcal/day

    ALL forms of exercise will burn fat, even at Max VO2

    Amount of fat burned during exercise is NOT important.

    Total calories used during exercise IS important

a   For patients/clients, pick an exercise/activity modality that
    they will do and do regularly. Type of exercise less important
       Exercise prescription
 To treat various diseases
 Primary prevention—PE class
 Clinically—discuss exercise
 Work—corporate wellness
 End of college, athletic endeavors—need
  to have scheduled exercise
 60 min daily
 Aerobic and resistance
 Convenient
 Traveling
 Pedometer
 Minutes per day
 Intensity, duration, frequency (need to
  vary)
          Routine exercise
 Improves tissue oxygen uptake
 HDL
 LDL
 TG
 BP
 Glycemic control
       Decreased risk of CA
 Endometrial
 Breast
 Colon
 prostate
            Cognitive benefits
   Better adjusted
   Cognitive tests
   Decreased CV response to stress
   Anxiety
   Depression
   People who were active and became inactive
    were 1.5x more likely to become depressed
   CAD and depression
          Cognitive cont’d
 Improves self confidence
 Self esteem
 Decrease CV and neurohormonal
  response to stress
 Short bouts of exercise—cognitive
  improvement
              compliance
 Long term adherence to exercise
 Decrease with age, minorities, females,
  disabled, chronic dz
 Exercise program—50% cont for >6 mo
          Types of exercise
 Occupational, recreational, sports
 Aerobic
 Anaerobic—sprint
 Isometric—wts
         Resistance training
 Resistance to contracting muscles to
  stimulate them for increased strength
 Injury risk—decreased
 Lean tissue and aging
 Heart conditions—don’t strain or hold
  breath
    How to make exercise a lifetime
              activity
 Pick activity that is enjoyable and uses
  most muscles
 Vary duration, intensity
 Group classes
 Music
 Walk the dog!
 Set goals—health, appearance,
  cholesterol
                  Elderly
 Joint flexibility
 Muscle strength
 LBM
 Balance
 Prevention of injury
            Pulmonary dz
 Low workloads, short duration
 Frequent intervals
 Supplemental O2
                  Maternity
   Maternal
     Increased CV fxn
     Decreased wt gain and fluid
     Mental state
     Labor
     Recovery
     fitness
                  maternity
   Fetus
     Decreased fat
     Improved stress
     Neurobehavioral maturation
             osteoporosis
 BMD
 Muscle—balance, falls, fracture
 Works with estrogen, diet
 Wt bearing
                    CAD
 Primary and secondary prevention
 Increased CV functional capacity and
  decreased myocardial O2 demand
 Lipids, DM, obesity
 BP—8-10 mmHg
 Inactivity is independent risk factor for
  CAD
 Sedentary have greatest CVD mortality
                   III. Application for Health Care
                            Obesity
                            Type II Diabetes




    - Obesity is reaching "epidemic proportions” in the United
    States
    - could soon cause as much preventable disease and death as
    cigarette smoking.



For the vast majority of individuals, overweight and obesity
result from excess calorie consumption and/or inadequate physical activity.

Unhealthy dietary habits and sedentary behavior together account
for approximately 300,000 deaths every year.
                    Exercise and Type II Diabetes
                    Position statement ACSM



About 10.3 million diagnosed cases and about 5.4 million undiagnosed

Accounts for 90-95% of all cases of diabetes

Characterized by insulin resistance and moderate insulin deficiency



  Skeletal muscle: site of about 80-90% of glucose uptake
          insulin and contraction act INDEPENDENTLY to increase
          GLUT4 translocation and glucose uptake.
          Ideal target for exercise and/or pharmacological therapies
             Acute Effects of Physical Activity

             Glucose Levels


Most obese Type II diabetics experience decreases in blood
glucose following mild-moderate exercise

       magnitude of effect is dependent on duration and intensity

       blood glucose increases with short term high intensity exercise
                Insulin resistance


Insulin resistant individuals have 35-40% reduction in
insulin mediated glucose uptake

Low to moderate intensity exercise improves insulin sensitivity

High intensity exercise variable response

Transient effect (about 72 hrs) so requires regular activity
        not really the “trained state”
Physiological Benefits of Exercise for those with Type II Diabetes



                      Lower resting heart rate
                      Lower submaximal exercise heart rate
                      Increased stroke volume
                      Increased cardiac output
                      Enhanced oxygen extraction
                      Lower resting BP
                      Lower exercise BP
                      Influence lipid profile
              Psychological Benefits of Exercise


Reduced stress response to psychosocial stimuli
Lessened sympathetic nervous system activation to cognitive stress
Reductions in depression
Improved self-esteem
Reduction in emotional perturbations to stress




    Contribute to sustained behavioral changes and adherence
          Exercise and Chronic Diseases
          Booth et al., 2000


Cardiovascular Disease
Type II Diabetes
Obesity
Obesity related diseases
Aging

While all these diseases have some contribution from
genetic the rapid increases in the last 20+ years are
due to environmental factors.

Sedentary living is responsible for about 34% of deaths due to
coronary heart disease, colon cancer and Type II diabetes

CDC has concluded that “physical inactivity is one of the major
underlying causes of premature mortality in the US”
    Take home message
1. Consider exercise/physical activity for both
disease prevention as well as treatment

2. When considering exercise think movement
or activity not athletic performance

3. Consider the importance of exercise
for children. Growing evidence for mental as well as
physical development. Educate for healthy lifestyle

• Good resource for exercise and health information
American College of Sports Medicine www.acsm.org

				
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