Chapter 10

1. Chapter 10 Energy Expenditure During Walking, Jogging, Running, and Swimming McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

2. Gross Versus Net Energy Expenditure • Energy expenditure estimates • Gross energy expenditure • Total energy required for an activity • Net energy expenditure • Gross energy expenditure – Resting energy expenditure McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

3. Economy of Human Movement • Economy of movement refers to the energy required to maintain a constant velocity of movement. • More skilled athletes perform the same activity with a reduced energy requirement. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

4. Mechanical Efficiency • Mechanical efficiency • Ratio of energy output / energy input • Reflects the amount of energy transferred into doing work • External work is measured as F × D • Ft-lb • Kg-m • kCal McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

5. Walking • Influence of body mass • Equations may be used to calculate energy expenditure. • Speed or pace is an important factor. • Mass is factored in as resistance. • Individuals with a larger mass expend more energy at the same pace. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

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7. Walking • Terrain and walking surface • Energy expenditure is greater on soft surfaces. • Sand • Snow • Slope or grade influences energy expenditure. • Downhill walking requires less energy. • Very steep downhills require energy to “brake.” • Uphill grades require more energy. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

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9. Walking • Footwear • Added weight to feet or legs increases energy requirements. • Shoes need to balance cushioning effects with weight. • Handheld and ankle weights • Increase energy expenditure • Used during walking, increase energy expenditure closer to that of running • Have less of an impact on energy expenditure while running McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

10. Competition Walking • Economy is not good in this type of walking. • Energy expenditure increases at a faster rate or a greater slope for competitive walking compared to running. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

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12. Running • Economy of running fast or slowly • Net energy cost values for running a set distance are similar for different speeds. • Stride length, stride frequency, and speed • Running • Speed is dependent upon stride length & stride frequency. • Competition walking • Speed is increased mainly by increasing stride frequency. • Optimum stride length • Level of minimum effort • No “best” style McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

13. Running • Running economy: Children and adults • Children have lower running economy than adults. • Children require 20 – 30% more oxygen per unit of mass to run at the same pace as an adult. • Air resistance • Factors that effect air resistance • Air density • Runner’s projected surface area • Square of runner’s velocity • Drafting • Decreases resistance McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

14. Running • Treadmill versus track running • Have similar energy requirements at the same speed • Elite athletes at top speeds on the track may encounter increased air resistance. • Marathon running • To be successful requires the ability to maintain pace for an extended period of time McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

15. Swimming • Methods of measurement • Portable metabolic systems may be worn. • Subjects may be tethered. • Subjects may swim in a flume. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

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20. Swimming • Energy cost and drag • Total drag force • Wave drag • Skin friction drag • Viscous pressure drag • Ways to reduce effects of drag force • Wet suits • Drafting McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

21. Swimming • Energy cost, swimming velocity, and skill • Skilled swimmers are more efficient. • More of their effort provides forward movement. • The stroke used influences energy cost. • Freestyle or front crawl is more efficient than back crawl or breaststroke. • Breaststroke is less efficient than freestyle or back crawl. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

22. Swimming • Effects of water temperature • Cold water adds additional energy costs. • Optimal temperature is ~ 82 – 86°F. • Effects of buoyancy: Men versus women • The leaner an individual, the less buoyant. • Women tend to be more economical due to added buoyancy. • Endurance swimming is influenced by economy and thermal insulation provided by body fat. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition