Does anyone know how efficient human muscle tissue is as a means of converting stored energy into mechanical work? More precisely, how much stored energy (in terms of ATP, fatty acids or glycogen -- say, expressed in calories) must a muscle burn in order to perform one foot-pound of mechanical work? Of course this will depend on a lot of things (age, conditioning, fatigue level,etc.), but just a range or ballpark estimate would be useful.
(I am trying to estimate the energy expenditure of various activities using this approach.)
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Former Member
Energy expenditure in sports activities is always fun to calculate...For a thorough understanding you can look at chapter 19 in Wilmore and Costill (Physiology in exercise and sport). They describe the energy cost of lots of activities…remember that the people they tested may not do the activities regularly and with regular activity these numbers will go down (increased economy).
On the direct answer to your question…when we teach this in biomechanics we use ~25% efficiency of metabolic to physical work. We also use 1/3 as the relationship between positive (concentric) to negative (eccentric) work. If you use the previous 6000 ft-lbs, you multiply by 4 to get 24000 then take 1/3 or 8000 and add for a total of 32000 ft-lbs. This is slightly lower than the other methods and using anywhere for 15-30% efficiency is probably good. In swimming, there is another aspect to be considered…the best swimmers are only ~85% efficient in the water.
Energy expenditure in sports activities is always fun to calculate...For a thorough understanding you can look at chapter 19 in Wilmore and Costill (Physiology in exercise and sport). They describe the energy cost of lots of activities…remember that the people they tested may not do the activities regularly and with regular activity these numbers will go down (increased economy).
On the direct answer to your question…when we teach this in biomechanics we use ~25% efficiency of metabolic to physical work. We also use 1/3 as the relationship between positive (concentric) to negative (eccentric) work. If you use the previous 6000 ft-lbs, you multiply by 4 to get 24000 then take 1/3 or 8000 and add for a total of 32000 ft-lbs. This is slightly lower than the other methods and using anywhere for 15-30% efficiency is probably good. In swimming, there is another aspect to be considered…the best swimmers are only ~85% efficient in the water.
