Physiology is the part of biology that studies the biophysical and biochemical functions of living organisms, including humans, or in simpler terms, how an organism or body system works.
In particular, Exercise Physiology focuses on how our body works during exercise. It is the study of acute reactions and chronic adjustments in a wide range of exercise conditions.
People have a great ability to consume energy for many hours during prolonged exercise.
Skeletal muscles in sleep have a basal metabolic rate (consumption of resting energy) of 0.63 W / kg . For short-term muscle exercise, energy consumption may be much greater: for example, an adult man jumping from the “deep seat” position can mechanically produce 314 W / kg causing a 160-fold difference between energy consumption of inactive and active muscles.
This energy expenditure is very high compared to the basic metabolic rate of rest of the adult human body. This rate varies somewhat depending on size, sex and age, but is typically between 45 W and 85 W.  . Total Energy Expenditure (TEE) due to muscle energy consumption during the day is much higher and depends on the average level of physical work and exercise . Thus, exercise, especially if it is maintained for very long periods, dominates the energy metabolism of the body. The energy expenditure of physical activity is strongly correlated with sex, age, weight, heart rate and maximum oxygen intake (VO2-max – δs maximum aerobic capacity) of an individual during physical activity .
1. Elia, M. (1992) “Energy expenditure in the whole body”. Energy metabolism. Tissue determinants and cellular corollaries. 61–79 Raven Press New York. ISBN 978-0-88167-871-0
2. Henry, CJ (2005). “Basal metabolic rate studies in humans: Measurement and development of new equations”. Public health nutrition. 8 (7A): 1133–52.PMID 16277825 .
3. Henry 2005 provides BMR formula various ages given body weight: those for BMR aged 18–30 in MJ/day (where mass is body weight in kg) are: male BMR = 0.0669 mass + 2.28; females BMR = 0.0546 mass + 2.33; 1 MJ per day = 11.6 W. The data providing these formula hide a high variance: for men weighing 70 kg, measured BMR is between 50 and 110 W, and women weighing 60 kg, between 40 W and 90 W.
4. Torun, B (2005). “Energy requirements of children and adolescents”. Public health nutrition. 8 (7A): 968–93. PMID 16277815 .
5. Keytel, L.R. (March 2005). “Prediction of energy expenditure from heart rate monitoring during submaximal exercise.”(PDF). Journal of Sports Sciences: 10. Retrieved 16 April 2015.