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Exercise physiology
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==Energy expenditure== Humans have a high capacity to expend [[Oxidative phosphorylation|energy]] for many hours during sustained exertion. For example, one individual cycling at a speed of {{convert|26.4|km/h|mph|abbr=on}} through {{convert|8204|km|mi|abbr=on}} over 50 consecutive days expended a total of 1,145 MJ (273,850 kcal; 273,850 dieter calories) with an average power output of 173.8 W.<ref>{{Cite journal |last=Gianetti |first=G |last2=Burton |first2=L |last3=Donovan |first3=R |last4=Allen |first4=G |last5=Pescatello |first5=LS |year=2008 |title=Physiologic and psychological responses of an athlete cycling 100+ miles daily for 50 consecutive days |journal=Current Sports Medicine Reports |volume=7 |issue=6 |pages=343β7 |doi=10.1249/JSR.0b013e31818f0670 |pmid=19005357 |doi-access=free}}. This individual while exceptional was not physiologically extraordinary since he was described as "subelite" due to his not being "able to adjust power output to regulate energy expenditure as occurs with elite athletes during ultra-cycling events" page 347.</ref> Skeletal muscle burns 90 mg (0.5 [[Mole (unit)|mmol]]) of glucose each minute during continuous activity (such as when repetitively extending the human knee),<ref name="Richter, E. A. 1988">{{Cite journal |last=Richter |first=EA |last2=Kiens |first2=B |last3=Saltin |first3=B |last4=Christensen |first4=NJ |last5=Savard |first5=G |year=1988 |title=Skeletal muscle glucose uptake during dynamic exercise in humans: Role of muscle mass |journal=The American Journal of Physiology |volume=254 |issue=5 Pt 1 |pages=E555β61 |doi=10.1152/ajpendo.1988.254.5.E555 |pmid=3284382}}</ref> generating β24 W of mechanical energy, and since muscle energy conversion is only 22β26% efficient,<ref>{{Cite journal |last=Bangsbo |first=J |year=1996 |title=Physiological factors associated with efficiency in high intensity exercise |journal=Sports Medicine |volume=22 |issue=5 |pages=299β305 |doi=10.2165/00007256-199622050-00003 |pmid=8923647 |s2cid=23080799}}</ref> β76 W of heat energy. Resting skeletal muscle has a [[basal metabolic rate]] (resting energy consumption) of 0.63 W/kg<ref>Elia, M. (1992) "Energy expenditure in the whole body". Energy metabolism. Tissue determinants and cellular corollaries. 61β79 Raven Press New York. {{ISBN|978-0-88167-871-0}}</ref> making a 160 fold difference between the energy consumption of inactive and active muscles. For short duration muscular exertion, energy expenditure can be far greater: an adult human male when jumping up from a squat can mechanically generate 314 W/kg. Such rapid movement can generate twice this amount in nonhuman animals such as [[bonobo]]s,<ref>{{Cite journal |last=Scholz |first=MN |last2=d'AoΓ»t |first2=K |last3=Bobbert |first3=MF |last4=Aerts |first4=P |year=2006 |title=Vertical jumping performance of bonobo (Pan paniscus) suggests superior muscle properties |journal=Proceedings: Biological Sciences |volume=273 |issue=1598 |pages=2177β84 |doi=10.1098/rspb.2006.3568 |pmc=1635523 |pmid=16901837}}</ref> and in some small lizards.<ref>{{Cite journal |last=Curtin NA, Woledge RC, Aerts P |year=2005 |title=Muscle directly meets the vast power demands in agile lizards |journal=Proceedings: Biological Sciences |volume=272 |issue=1563 |pages=581β4 |doi=10.1098/rspb.2004.2982 |pmc=1564073 |pmid=15817432}}</ref> This energy expenditure is very large compared to the basal resting metabolic rate of the adult human body. This rate varies somewhat with size, gender and age but is typically between 45 W and 85 W.<ref>{{Cite journal |last=Henry |first=CJ |year=2005 |title=Basal metabolic rate studies in humans: Measurement and development of new equations |journal=Public Health Nutrition |volume=8 |issue=7A |pages=1133β52 |doi=10.1079/phn2005801 |pmid=16277825 |doi-access=free}}</ref> <ref>Henry 2005 provides BMR formula various ages given body weight: those for BMR aged 18β30 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.</ref> Total energy expenditure ([[Total energy expenditure|TEE]]) due to muscular expended energy is much higher and depends upon the average level of physical work and exercise done during the day.<ref>{{Cite journal |last=Torun |first=B |year=2005 |title=Energy requirements of children and adolescents |journal=Public Health Nutrition |volume=8 |issue=7A |pages=968β93 |doi=10.1079/phn2005791 |pmid=16277815 |doi-access=free}}</ref> Thus exercise, particularly if sustained for very long periods, dominates the energy metabolism of the body. Physical activity energy expenditure correlates strongly with the gender, age, weight, heart rate, and [[VO2 max|VO<sub>2</sub> max]] of an individual, during physical activity.<ref>{{Cite journal |last=Keytel |first=L.R. |date=March 2005 |title=Prediction of energy expenditure from heart rate monitoring during submaximal exercise |url=http://www.procalcdiet.com/storage/Predictionofenergy.pdf |url-status=dead |journal=Journal of Sports Sciences |volume=23 |issue=3 |pages=289β97 |doi=10.1080/02640410470001730089 |pmid=15966347 |s2cid=14267971 |archive-url=https://web.archive.org/web/20150416185146/http://www.procalcdiet.com/storage/Predictionofenergy.pdf |archive-date=16 April 2015 |access-date=16 April 2015}}</ref>
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