1. ACSM Exercise Specialist Workshop Metabolic Calculations Tutorial

2. Purpose of Metabolic Calculations Under steady-state conditions, VO 2 provides a measure of the energy cost of exercise The rate of O 2 uptake at maximal exercise indicates the capacity for O 2 transport and utilization Peak VO 2 serves as the gold standard criterion measure of cardiorespiratory fitness At steady state, and in combination with CO 2 output, VO 2 can provide information about type of fuel use during exercise Determine work rates to be used in the development of exercise prescription

3. Expression of VO 2 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 VO 2 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

4. RER and RQ RER-Respiratory Exchange Ratio Ventilatory measurement Reflects gas exchange between lungs and pulmonary blood Exceeds 1.0 during heavy exercise due to buffering of lactic acid which produces CO 2 RQ-Respiratory Quotient Cellular Respiration and substrate utilization 0.7 = Fat 1.0 = Carbohydrate 0.8 = Protein Equivalent to RER only under resting or steady-state conditions Can never exceed 1.0 RQ is used to estimate energy expenditure, however, when RQ is not available, assume 5 kcal L -1

5. Estimation of Energy Expenditure When VO 2 cannot be measured directly, estimations can be made during steady- state exercise (will overestimate VO 2 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

6. 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

7. Cautionary Notes The inter-subject variability for VO 2 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

8. 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 O 2 min -1 = 5 kcalmin -1 1 in= 0.0254m=2.54 cm

9. Located in Appendix D of GETP6

10. Conversion Flowchart METS mL  kg -1  min -1 mL min -1 L  min -1 Kcal min -1 Total kcal lb fat loss/gain X 3.5 X BW X 1000X 5 X Tot min 3500  3.5  BW  1000 5  Tot min X 3500

11. Walking (1.9  3.75 mph) VO 2 = (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: VO 2 is reported as mLkg -1 min -1

13. 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: VO 2 is reported as mLkg -1 min -1

15. Leg Ergometry VO 2 = (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: VO 2 is reported as mLkg -1 min -1

17. Arm Ergometry VO 2 = 18(W/M) + 3.5 Find work rate the same as leg ergometry Major difference: D=2.4 for Monark NOTE: VO 2 is reported as mLkg -1 min -1

19. Stepping Ergometry VO 2 = (0.2 f) + (1.33 1.8 f h) + 3.5 f=stepping rate h=height of step in m NOTE: VO 2 is reported as mLkg -1 min - 1

20. Question #1 VO 2 = (0.1x85.76)+(1.8x85.76x.06)+3.5 VO 2 = 8.576 + 9.26 + 3.5 VO 2 = 21.34 mLkg -1 min - 1 21.34/3.5 = 6.1 METs

21. Question #2 VO 2 = (0.2x241.2)+(0.9x241.2x.01)+3.5 VO 2 = 48.24 + 2.17 + 3.5 VO 2 = 53.9 mLkg -1 min -1 VO 2 = 53.9 mLkg -1 min -1 x 68.0 kg=3665.2 mLmin -1 VO 2 (Lmin -1 ) =3665.2 mLmin -1 /1000 mLL -1 = 3.67 Lmin -1 Kcalsmin -1 = 3.67 Lmin -1 x5 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

22. Question #3 50 kg man walking at 75% VO 2 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

23. Question #4 VO 2 = (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%

24. Question #5 VO 2 = (18 x W/M) + 3.5 where W = 0.5kg x 2.4m x 50rpm w=60 kgmmin - 1 or 10 watts VO 2 mLkg -1 min - 1 = (18 x 10)/50 + 3.5 VO 2 = 180/50 + 3.5 VO 2 = 3.6 + 3.5 VO 2 = 7.1 mLkg -1 min - 1

25. 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 -1 x80 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.

26. 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

27. 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

28. Question #7 140 lbs = 63.6 kg TM @ 3.2/0% VO 2 = 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

29. Question # 8 MET level of person with VO 2 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

30. Question # 9 60 kg women with a VO 2 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

31. Question #10 70 kg person using Stepper @ 18 steps min - 1, 25 cm step VO 2 = (0.2 x f)+(1.33 x 1.8 x H x F) +3.5 VO 2 = (0.2 x 18) + (1.33x1.8x0.25x18) VO 2 = 3.6 + 10.8 VO 2 = 14.4 mLkg -1 min - 1 or 4.1 METs

32. 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 VO 2 = (10.8x125)/70 + 7 VO 2 = 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)

33. Question #10…continued 70 kg person on Monark arm ergometer @ 350 kgmmin - 1. 350 kgmmin - 1 = 58.3 watts VO 2 = (18x58.3)/70 + 3.5 VO 2 = 14.99 + 3.5 VO 2 = 18.49 or 5.3 METs

34. Question # 11 Who is exercising harder, Fred or Pete? Fred(72 kg) VO 2 = (0.2x160.8) + (0.9x160.8x0.1)+3.5 VO 2 = 32.16 + 14.47 + 3.5 VO 2 = 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

35. 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%

36. Question # 13 Functional capacity of 70 kg male completing stage 5 (3mph/12%) of Balke protocol. 3 mph = 80.4 mmin - 1 VO 2 = (0.1x80.4) + (1.8x80.4x0.12)+3.5 VO 2 = 8.04 + 17.37 + 3.5 Relative VO 2 = 28.9 mLkg -1 min - 1 or 8.3 METs Absolute VO 2 = 2023 mLmin - 1 or 2.02 Lmin - 1

37. Question # 14 MET level of man running @ 7 mph and 5% grade 7 mph = 187.6 mmin - 1 VO 2 = (0.2x187.6)+(0.9x187.6x0.05)+3.5 VO 2 = 37.52 + 8.44 + 3.5 VO 2 = 49.46 mLkg -1 min - 1 or 14.1 METs

38. Question # 15 What is kcal utilization over 20 minutes on the cycle ergometer if VO 2 = 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

39. Questions