EXSS1010 Lecture Notes - Lecture 8: Physical Fitness, British Association For Immediate Care
30 May 2018
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EXSS1010 – ENERGY EXPENDITURE DURING MOVEMENT
LECTURE OBJECTIVES
1. Understand basic terms such as exercise economy and efficiency
2. Discuss how energy expenditure changes at increasing speeds
3. Describe the influencing factors to energy expenditure during swimming
4. Describe commonly used tests for anaerobic and aerobic capacities
5. Understand why and how heart rate can be used to estimate maximal aerobic
capacity
BASICS CONCEPTS IN HUMAN ENERGY EXPENDITURE DURING MOVEMENT
GROSS VS. NET ENERGY EXPENDITURE
• Gross energy expenditure refers to the total energy cost to perform an activity
• Net energy expenditure (NEE) is the true energy expenditure of an activity
o NEE = Gross energy expenditure - resting energy expenditure
• Calculating energy expenditure for intermittent activities with considerable variation
in intensity require more continuous measurement
o Football
o Rugby
o Tennis
ECONOMY OF MOVEMENT
• The energy required to maintain a constant velocity of movement
• Influenced by:
o Physical fitness levels
o Type of activity
o Environmental conditions
• Measurement requires evaluation of VO2 during steady-rate exercise
• Takes on added importance during longer-duration endurance exercise
MECHANICAL EFFICIENCY (ME)
Energy required to perform task (mechanical)
Vs
Actual energy requirement of the work (biological)
• Reflects the percentage of total chemical energy expended that contributes to
external work
o Remainder lost by heat
Me (%) = external work accomplished ÷ energy expenditure x 100
• Efficiency of humans for mechanical work is bellow 100%
o The energy required to overcome internal and external friction is the largest
affecting factor
• Efficiency averages between 20-25% for walking, running and stationary cycling
• Body size, gender, fitness level, and skill affect individual bodies
ENERGY EXPENDITURE DURING WALKING
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Document Summary
Basics concepts in human energy expenditure during movement. Economy of movement: the energy required to maintain a constant velocity of movement. Influenced by: physical fitness levels, type of activity, environmental conditions, measurement requires evaluation of vo2 during steady-rate exercise, takes on added importance during longer-duration endurance exercise. Actual energy requirement of the work (biological: reflects the percentage of total chemical energy expended that contributes to external work, remainder lost by heat. Linear relationship between walking speed and vo2 at slower speeds: at faster speeds, walking economy decreases, changes in biomechanics and techniques. Walking vs running: as speeds increase it becomes more economical to run than walk. Independent of fitness: threshold ~8 km/hr (becomes more efficient to run than walk, with a distinct modified walking technique achieve high yet uneconomical rates of movement. Increasing running speed: running speed can be increased in 3 ways: Increase the number of steps each minute (stride frequency)
