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Energy Expenditure during various Activities

Energy Expenditure during various Activities. Oxygen Uptake. Energy utilized for O 2 consumed: 5 kcal/L of O 2 If a person burns 600 calories during a run, how many liters of O 2 did he/she consume?. Energy Expenditure. Gross Energy Expenditure Net Energy Expenditure

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Energy Expenditure during various Activities

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  1. Energy Expenditure during various Activities

  2. Oxygen Uptake Energy utilized for O2 consumed: • 5 kcal/L of O2 • If a person burns 600 calories during a run, how many liters of O2 did he/she consume?

  3. Energy Expenditure Gross Energy Expenditure Net Energy Expenditure • expenditure due to activity • subtract resting energy expenditure

  4. Energy Expenditure A runner burns 600 calories during a 45 minute run: • 6’0” • 190 lbs. • Age: 37 • Find Net Energy Expenditure

  5. Energy Expenditure Runner • Estimate Body Surface Area (nomogram - Figure 9.4) • Estimate BMR (Figure 9.3) • Calculate Resting Energy Expenditure (kcal/hour)

  6. Energy Expenditure Net Energy Expenditure = Gross Energy Expenditure – BMR

  7. Energy Expenditure/O2 Consumption Constant load / light to moderate exercise • Assessed 1-2x during steady state Exercise w/ varying loads • Assessed multiple times

  8. Mechanical Efficiency (%) • = Mechanical work accomplished / Input of energy * 100 • Mechanical work = ergometer • Energy input = O2 consumption • Work equivalent: 1 kcal = 426 kg-m perfect)

  9. Mechanical Efficiency (%) • Human locomotion = 20-30% • Dissipated energy to internal & external friction

  10. Walking Efficiency • Sand  2x energy expenditure • Soft-soled running shoe   O2 consumption x 2.4% • 100g (3.52 oz.) to each shoe   O2 consumption x 1%

  11. Effects of Downhill Walking 14 13 12 11 10 Net Oxygen Consumption (mL/kg-min) 9 8 7 6 5 -18 -15 -13 -9 -6 -3 0 % Grade

  12. Walking vs. Running

  13. Running Economy • Energy cost not dependent on velocity • Horizontal running  net energy expenditure = 1kcal/kg-km (1km = 0.62 miles) • A 220 lb. man runs 10 km, what is the net energy expenditure?

  14. Running: Frequency vs. Stride Length Frequency Stride Frequency and Stride Length (cm) Length 90 20 30 10 Speed (km/h)

  15. Frequency Stride Frequency and Stride Length (cm) Length 10 16 Speed (km/h) Walking: Frequency vs. Stride Length 220 120

  16. Stride Length 3.9 Oxygen Uptake (L/min) 3.7 3.5 3.3 134 154 118 Stride Length (cm)

  17. Air Resistance Effect dependent on: • air density • surface area • velocity2 • 9.86 vs. 41 mph wind • 2.92 vs. 4.1 L/min (41%)

  18. Drafting • Running @ 6 m/s • 1 m behind •  energy expenditure by 7% • Cycling @ 25 mph •  energy expenditure by 26-38%

  19. Treadmill vs. Non-Tmill Running • No differences aerobically (submax and max)

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