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Work, Power, and Energy Expenditure Dr. Kyle Coffey

Work, Power, and Energy Expenditure Dr. Kyle Coffey. Answers & Additional Practice Questions. Estimating O 2 Consumption and Energy Expenditure from Submaximal Steady-State Exercise. = R (rest) + H (horizontal) + V (vertical) Running R = 3.5ml/kg/min H = 0.2 (running speed in m/min)

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Work, Power, and Energy Expenditure Dr. Kyle Coffey

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  1. Work, Power, and Energy ExpenditureDr. Kyle Coffey Answers & Additional Practice Questions

  2. Estimating O2 Consumption and Energy Expenditure from Submaximal Steady-State Exercise = R (rest) + H (horizontal) + V (vertical) Running R = 3.5ml/kg/min H = 0.2 (running speed in m/min) V = 0.9 (running speed in m/min) x (grade as %) Walking R = 3.5ml/kg/min H = 0.1 (walking speed in m/min) V = 1.8 (walking speed in m/min) x (grade as %) Answer is in ml/kg/min of oxygen consumption

  3. Estimating O2 Consumption and Energy Expenditure from Submaximal Steady-State Exercise = R (rest) + H (horizontal) + V (vertical) Cycling R = 3.5ml/kg/min x body weight in kg H = 0 V = 2 x (power output in kgm/min) Answer is in ml or L of oxygen consumption per min*

  4. REMINDER: Common Formulas and Conversions 1 kilogram (kg) = 2.2 pounds (1bs) 1 mile per hour (mph) = 26.8 meters/min 1 Watt = 6.12 kgm/min* 1 Watt = .01433 kcal/min* 1 kgm = .00235 kcal 1 kcal = 4.186 kj 5 kcal = 1 L O2 consumed 1 mile = 1.6129 km 1 lb fat = ~3,500 kcal 60 / “minutes per mile” = mph

  5. Estimating O2 Consumption and Energy Expenditure from Submaximal Steady-State Exercise Sample calculations: Q: What is the estimated oxygen consumption and how many kcal/min does a person (70kg) burn when running a 9-minute mile pace on a flat surface? How?

  6. Estimating O2 Consumption and Energy Expenditure from Submaximal Steady-State Exercise Sample calculations: Q: What is the estimated oxygen consumption and how many kcal/min does a person (70kg) burn when running a 9-minute mile pace on a flat surface? How? R = 3.5ml/kg/min H = .2 (60 / 9min/mile = 6.66mph x 26.8 = 178.66m/min) = 35.7 ml/kg/min V = 0 3.5 + 35.7 = 39.2 ml/kg/min x 70kg = 2744ml/min / 1000 = 2.744 L/min x 5kcal/L = 13.7 kcal/min

  7. Estimating O2 Consumption and Energy Expenditure from Submaximal Steady-State Exercise Sample calculations: Q: A person (180 lbs) walks on a treadmill at 3.5 mph and at a 15% grade for 20 minutes. What is the estimated oxygen consumption? How many kcal did they burn? What is their average MET level? How?

  8. Estimating O2 Consumption and Energy Expenditure from Submaximal Steady-State Exercise Sample calculations: Q: A person (180 lbs) walks on a treadmill at 3.5 mph and at a 15% grade for 20 minutes. What is the estimated oxygen consumption? How many kcal in total did they burn? What is their average MET level? How? R = 3.5ml/kg/min H = .1 (3.5mph x 26.8 = 93.8m/min) = 9.38 V = 1.8 (93.8m/min) x (.15) = 25.33 180 lbs/2.2 = 81.8 kg 3.5 + 9.38 + 25.33 = 38.2 ml/kg/min x 81.8 kg = 3124ml/min / 1000 = 3.124 L/min x 5kcal/L = 15.62kcal/min x 20min = 312 kcal 38.2 ml/kg/min /3.5 ml/kg/min =10.9 METs

  9. Estimating O2 Consumption and Energy Expenditure from Submaximal Steady-State Exercise Sample calculations: Q: A person (150 lbs) pedals at 60 rev/min on a Monark* cycle ergometer against a resistance of 2.5 kg for 30 minutes. What is the estimated oxygen consumption and how many kcal did this person burn? Keeping all other things constant, how long (days) will it take this person to lose 1 kg of body fat if they continue daily? How?

  10. Estimating O2 Consumption and Energy Expenditure from Submaximal Steady-State Exercise Sample calculations: Q: A person (150 lbs) pedals at 60 rev/min on a Monark* cycle ergometer against a resistance of 2.5 kg for 30 minutes. What is the estimated oxygen consumption and how many kcal did this person burn? Keeping all other things constant, how long (days) will it take this person to lose 1 kg of body fat if they continue daily? How? 150 lbs/2.2 lbs = 68.18 kg Work = (2.5 kg X 6m/rev X 60 rev/min * 30 min) = 27000 J Power output = 27000 J/ 1800 seconds = 15 W R = 3.5ml/kg/min x 68.18 kg = 238.6 ml/min H = 0 V = 2 X (15 W X 6.12kgm/min) = 183.6 ml/min 238.6 + 183.6 = 422.2 ml/min /1000 = .4222 L/min x 5kcal/L = 2.111 kcal/min x 30min = 63.3 kcal 2.2 lbs fat = 3500kcal X 2.2 = 7700kcal 7700kcal / 63.3 kcal/day = ~121.6 days

  11. More Practice #1 Q: A person (120 lbs) is running at 4.0mph at a 5% incline for 15 minutes. She then increases her speed to 6.0 mph at 10% incline for 3 minutes. What is the estimated oxygen consumption for each stage and how many total kcal did this person burn while she was exercising?

  12. More Practice! #1 Sample calculations: Q: A person (120 lbs) is running at 4.0mph at a 5% incline for 15 minutes. She then increases her speed to 6.0 mph at 10% incline for 3 minutes. What is the estimated oxygen consumptionfor each stage and how many total kcaldid this person burn while she was exercising? How? Stage 1 R = 3.5ml/kg/min H = .2 (4.0mph x 26.8 = 107.2m/min) = 21.44 ml/kg/min V = 0.9 (107.2 m/min) x (.05) = 4.824 ml/kg/min Total = 29.76 ml/kg/min Stage 2 R = 3.5ml/kg/min H = .2 (6.0 mph x 26.8 = 160.8 m/min) = 32.16 ml/kg/min V = 0.9 (160.8 m/min) x (.10) = 14.47 ml/kg/min Total = 50.13 ml/kg/min

  13. More Practice! #1 (Cont’d) 120 lbs/ 2.2 lbs = 54.54 kg Stage 1 3.5 + 21.44 + 4.824 = 29.76 ml/kg/min x 54.54kg = 1623.27ml/min / 1000 = 1.623L/min x 5kcal/L = 8.12 kcal/min X 15 minutes = 121.75 Kcal Stage 2 3.5 + 32.16 + 14.47 = 50.13 ml/kg/min x 54.54kg = 2734.1ml/min / 1000 = 2.734L/min x 5kcal/L = 13.67 kcal/min X 3 minutes = 41.01 Kcal TOTAL: 121.75 + 41.01 = 162.76 Kcal

  14. More Practice! #2 Q: Keeping all other things constant, how long (days) will it take a 175lb person to lose 1.5 kg of body fat if they continue daily with using a cycle ergometer (Monark) with a resistance of 4.0 kg, 70 rev/min for 35 minute sessions?

  15. More Practice! #2 (Cont’d) Sample calculations: Q: Keeping all other things constant, how long (days) will it take a 175lb person to lose 1.5 kg of body fat if they continue daily with using a cycle ergometer (Monark) with a resistance of 4.0 kg, 70 rev/min for 35 minute sessions? How? 175 lbs/2.2 lbs = 79.54 kg Work = 4.0 kg X 6m/rev X 70 rev/min X 35 min = 58800 J Power = 58800 J/2100 sec = 28 W R = 3.5ml/kg/min x 79.54 kg = 278.41ml/min H = 0 V = 2 X (28 W X 6.12 kgm/min) = 342.72 ml/min 278.41 + 342.72 = 621.13 ml/min /1000 ml = .62116 L/min x 5kcal/L = 3.11 kcal/min x 35min = 108.85 kcal 3.3 lbs fat = 3500kcal X 3.3 = 11550kcal 11550kcal / 108.85 kcal/day = ~106 days

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