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2005 ES metabolic calc tutorial

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2005 ES metabolic calc tutorial Powered By Docstoc
					  ACSM Exercise
Specialist Workshop

      Metabolic
     Calculations
       Tutorial
            Purpose of
       Metabolic Calculations
   Under steady-state conditions, VO2 provides a
    measure of the energy cost of exercise
   The rate of O2 uptake at maximal exercise
    indicates the capacity for O2 transport and
    utilization
   Peak VO2 serves as the gold standard criterion
    measure of cardiorespiratory fitness
   At steady state, and in combination with CO2
    output, VO2 can provide information about type
    of fuel use during exercise
   Determine work rates to be used in the
    development of exercise prescription
Expression of VO2
   Absolute- Liters per minute (Lmin-1)
       Used to convert consumption to a rate of energy expenditure

   Relative- mL per kg body weight per min (mLkg-1min-1)
       Used to compare VO2 among varying body sizes

   Gross oxygen consumption- Total consumption rate under
    any circumstances, either in absolute or relative; describes
    rest plus exercise

   Net oxygen consumption- Consumption rate above resting
    oxygen uptake (approx. 3.5 mLkg-1min-1); describes
    exercise
                 RER and RQ
   RER-Respiratory                   RQ-Respiratory
    Exchange Ratio                     Quotient
       Ventilatory                       Cellular Respiration and
                                           substrate utilization
        measurement
                                            • 0.7 = Fat
       Reflects gas exchange               • 1.0 = Carbohydrate
        between lungs and                   • 0.8 = Protein
        pulmonary blood
                                          Equivalent to RER only
       Exceeds 1.0 during                 under resting or
        heavy exercise due to              steady-state conditions
        buffering of lactic acid          Can never exceed 1.0
        which produces CO2                RQ is used to estimate
                                           energy expenditure,
                                           however, when RQ is
                                           not available, assume
                                           5 kcal L-1
           Estimation of
        Energy Expenditure
   When VO2 cannot be measured directly,
    estimations can be made during steady-
    state exercise (will overestimate VO2 if
    not at steady-state)
   Equations are based on relating
    mechanical work rate to metabolic
    equivalents
   Equations are appropriate for general
    clinical and lab use
           Estimation of
        Energy Expenditure
   Equations can be used for:
     Estimating or predicting energy
      expenditure
     Designing an exercise prescription to
      determine the exercise intensity
      associated with a desired level of
      energy expenditure
Cautionary Notes
   The inter-subject variability for VO2 may be as
    high as 7%
   Appropriate for steady-state submaximal
    aerobic exercise
   Any variable that changes the metabolic
    efficiency results in loss of accuracy (e.g.,
    orthopedic limitations, holding handrail on
    treadmill, etc.)
   Assumes that a metabolic cart or gas analyzers
    and flow indicators are calibrated and used
    properly
   Despite these caveats, metabolic equations
    provide a valuable tool for exercise professionals
Conversion Factors

   1L= 1000 mL
   1kg= 2.2 lbs
   1mph= 26.8 mmin-1
   1lb of fat= 3500kcal
   1 MET=3.5 mLkg-1min-1
   1 W= 6 kgmmin-1
   1L O2min-1 = 5 kcalmin-1
   1 in= 0.0254m=2.54 cm
Located in Appendix D of GETP6
  Conversion Flowchart

    METS                           lb fat loss/gain

 3.5   X 3.5
                                       3500     X 3500

 mLkg-1min-1                          Total kcal
                                        X Tot    Tot
 BW    X BW
                                        min     min
            X 1000                X5
mLmin-1             L   min-1          Kcalmin-1
             1000                5
Walking (1.93.75 mph)
   VO2= (0.1S) + (1.8 S G) + 3.5
         Horizontal Vertical     Rest

S= speed in mmin-1 (convert if needed)
G= grade in decimal form (i.e., 5% is
    0.05); if 0% grade, then vertical=0
R= resting component
NOTE: VO2 is reported as mLkg-1min-1
Running (>5.0mph)
   VO2= (0.2 S) + (0.9 S G) + 3.5
          Horizontal Vertical     Rest

   All variables are the same as for
    walking
   NOTE: VO2 is reported as mLkg-1min-1
Leg Ergometry
   VO2= (10.8 W/M) + 7
   M= mass (weight) of subject in kg
   W= Work rate in watts,
       convert when necessary
       1 W= 6 kgmmin-1
       kgmmin-1=R D f
         • R= resistance in kg
         • D= distance of the fly wheel
            • 6m for Monark
            • 3m for Tunturi
         • f= frequency in rpm
   NOTE: VO2 is reported as mLkg-1min-1
Arm Ergometry
   VO2= 18(W/M) + 3.5

 Find work rate the same as leg
  ergometry
 Major difference:
       D=2.4 for Monark
   NOTE: VO2 is reported as mLkg-1min-1
    Stepping Ergometry
   VO2= (0.2 f) + (1.33 1.8 f h) + 3.5
     f=stepping rate
     h=height of step in m



   NOTE: VO2 is reported as mLkg-1min-1
Question #1
 VO2=
  (0.1x85.76)+(1.8x85.76x.06)+3.5
 VO2= 8.576 + 9.26 + 3.5
 VO2= 21.34 mLkg-1min-1


   21.34/3.5 = 6.1 METs
       Question #2
   VO2 = (0.2x241.2)+(0.9x241.2x.01)+3.5
   VO2 = 48.24 + 2.17 + 3.5
   VO2 = 53.9 mLkg-1min-1
   VO2 = 53.9 mLkg-1min-1 x 68.0 kg=3665.2 mLmin-1
   VO2(Lmin-1) =3665.2 mLmin-1/1000 mLL-1 = 3.67 Lmin-1
   Kcalsmin-1 = 3.67 Lmin-1x5 kcals L-1 =18.4 Kcalsmin-1
   Kcals in 40 minutes = 18.4 Kcalsmin-1 x 40min.= 736 kcals
    expended in 40 minutes
Question #3
   50 kg man walking at 75% VO2 reserve.
    Max VO2 = 2.4 Lmin-1. What speed at a
    grade of 12%.
   2.4 Lmin-1 = 2400 mLmin-1
   2400 mLmin-1 ÷ 50 kg = 48 mLkg-1min-1
   48 mLkg-1min-1 x 0.75 = 36 mLkg-1min-1
       •   36 = (0.1)(x) + (1.8)(x)(0.12) + 3.5
       •   36 = 0.1x + 0.21x + 3.5
       •   32.5 = 0.31x
       •   x = 104.8 mmin-1/26.8 mmin-1 = 3.9 mph
      Question #4
   VO2 = (0.2xS)+(0.9xSxG)+3.5
   45.0 mLkg-1min-1 =
    0.2x87.6)+(0.9x187.6xG)+3.5
   45.0 mLkg-1min-1 = 37.52 + 168.8(G) + 3.5
   3.98 = 168.8 (G)
   0.024 = G or 2.4%
    Question #5
   VO2 = (18 x W/M) + 3.5
     where W = 0.5kg x 2.4m x 50rpm
     w=60 kgmmin-1 or 10 watts

 VO2 mLkg-1min-1 = (18 x 10)/50 + 3.5
 VO2 = 180/50 + 3.5
 VO2 = 3.6 + 3.5
 VO2 = 7.1 mLkg-1min-1
    Question #6
   176 lbs/2.2 = 80 kg
   Warm Up
   2.5 x 3.5 = 8.75 mLkg-1min-1
   8.75 mLkg-1min-1x80 kg=700 mLmin-1
   700 mLmin-1 /1000 mLL-1 =0.7 Lmin-1
   0.7 Lmin-1 x 5 kcalsL-1 = 3.5 kcalsmin-1 x 5 min.
              = 17.5 kcals in 5 min.
       Question #6... continued
   Exercise
   4.5 METs = 15.75 mLkg-1min-1
   15.75mLkg-1min-1
        x 80kg = 1260 mLmin-1 = 1.26 Lmin-1
   1.26 Lmin-1 x 20 min =25.2 L x 5 kcal L-1 = 126 kcals
        in 20 min.

   4 METs = 14 mLkg-1min-1
   14 mLkg-1min-1 x 80 kg = 1120 mLmin-1 = 1.12 Lmin-1
   1.12 Lmin-1 x 15 min = 16.8 L x 5 kcal L-1 = 84 kcals
      Question # 6…continued
   Cool Down
   2 METs = 7 mLkg-1min-1/80kg =560 mLmin-1
   560 mLmin-1/1000 mLL-1 = 0.56 Lmin-1
   0.56 Lmin-1 x 5 min = 2.8 L
   2.8 L x 5 = 14 kcals

   17.5 + 126 + 84 + 14= 241.5 Kcals
Question #7
   140 lbs = 63.6 kg
   TM @ 3.2/0%
      VO2 = 8.576+3.5=12.08 mLkg-1min-1

      12.08 x 63.6 = 768.29 mLmin-1

      768.29/1000 = 0.768 Lmin-1

      0.768 x 10 = 7.7 l = 38.5 kcals
       • TM @ 3.4/2% = 50.5 kcals
       • TM @ 3.0/5% = 59.5 kcals
          • Total Kcals = 148.5
          • 148.5 x 3 = 445.5/week
          • 3500 x 15 = 52,500 kcals
          • 52, 500 kcals/445.5 = 118 weeks @ 3 days/week
   Question # 8
       •MET level of person with VO2 of 55
       mLkg-1min-1?



55 mLkg-1min-1 ÷ 3.5 mLkg-1min-1 per MET = 15.7 METs
    Question # 9
60 kg women with a VO2 of 2400
mLmin-1. What is her MET level?


2400 mLmin-1   ÷ 60kg = 40       mLkg-1min-1


   40 mLkg-1min-1 ÷ 3.5   mLkg-1min-1 per MET
      = 11.4 METS
    Question #10
   70 kg person using Stepper @ 18
    stepsmin-1, 25 cm step
      • VO2   =   (0.2 x f)+(1.33 x 1.8 x H x F) +3.5
      • VO2   =   (0.2 x 18) + (1.33x1.8x0.25x18)
      • VO2   =   3.6 + 10.8
      • VO2   =   14.4 mLkg-1min-1 or 4.1 METs
      Question 10…continued
   70 kg person on Monark @ 750          kgmmin-1
   750 kgmmin-1 / 6 kgmmin-1 per watt=
      125 watts
      • VO2 = (10.8x125)/70 + 7
      • VO2 = 18.9 + 7 = 25.9 mLkg-1min-1 or 7.5 METs

      • (NOTE: may get 7.4 METS if use 6.12 kgmmin-1
        as 1 watt)
Question #10…continued
 70 kg person on Monark arm
  ergometer @ 350 kgmmin-1.
 350 kgmmin-1 = 58.3 watts
    • VO2 = (18x58.3)/70 + 3.5
    • VO2 = 14.99 + 3.5
    • VO2 = 18.49 or 5.3 METs
     Question # 11
   Who is exercising harder, Fred or Pete?
     Fred(72 kg)
       • VO2 = (0.2x160.8) + (0.9x160.8x0.1)+3.5
       • VO2 = 32.16 + 14.47 + 3.5
       • VO2 = 50.13 mLkg-1min-1 or 14.3 METS
     Pete   (55 kg)
        •Power = 2.5kg x 6m x 60rpm= 900
        kgmmin-1 or 150 watts
        •VO2 = (10.8 x 150)/55 + 7 = 36.45 mLkg-
        1min-1 or 10.4 METS


                 •FRED is working harder
       Question # 12
   Desired exercise intensity = 8 METs;
    what is the grade at 3 mph
   3 mph x 26.8 mmin-1 per MPH = 80.4 mmin-1
     •28 mLkg-1min-1 = (0.1x80.4) + (1.8x80.4xG) + 3.5
     •28 = 8.04 + 144.7(G)+ 3.5
     •16.46 = 144.7 (G)
     •G= 11.4%
     Question # 13
   Functional capacity of 70 kg male
    completing stage 5 (3mph/12%) of
    Balke protocol.
       3 mph = 80.4 mmin-1
        • VO2 = (0.1x80.4) + (1.8x80.4x0.12)+3.5
        • VO2 = 8.04 + 17.37 + 3.5
        • Relative VO2 = 28.9 mLkg-1min-1 or 8.3 METs
        • Absolute VO2 = 2023 mLmin-1 or 2.02 Lmin-1
Question # 14
   MET level of man running @ 7mph
    and 5% grade
       7 mph = 187.6 mmin-1
        • VO2 = (0.2x187.6)+(0.9x187.6x0.05)+3.5
        • VO2 = 37.52 + 8.44 + 3.5
        • VO2 = 49.46 mLkg-1min-1 or 14.1 METs
Question # 15
   What is kcal utilization over 20
    minutes on the cycle ergometer if
    VO2 = 1745 mLmin-1.
      • 1745 mLmin-1 = 1.75 Lmin-1
      • 1.75 Lmin-1 x 5 kcalsL-1 = 8.75 kcalsmin-1
      • 8.75 kcalsmin-1 x 20 min = 175 kcals
        expended over 20 minutes
Questions

				
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