Energy expenditure during oxygen deficit of submaximal concentric and eccentric exercise

Abstract
Aerobic (.ovrhdot.MR) and anerobic (.ovrhdot.Man) energy production was determined in 5 human subjects during the 1st min of concentric and eccentric exercise (steady-state energy expenditure approximately 415 W in both situations). .ovrhdot.Man was obtained by solving the heat balance equation, .ovrhdot.MR + .ovrhdot.Man - .ovrhdot.S = (.ovrhdot.R + .ovrhdot.C + .ovrhdot.E) .+-. .ovrhdot.W , all other variables of which could be measured [.ovrhdot.S is heat storage; (.ovrhdot.R + .ovrhdot.C + .ovrhdot.E) are the radiative, convective, and evaporative heat losses; and .ovrhdot.W is work output]. Size of the O2 deficit was similar whatever the type of exercise (99 .+-. 19 W concentric and 102 .+-. 19 W eccentric). .ovrhdot.MR + .ovrhdot.Man was lower than the steady-state .ovrhdot.MR in both types of exercise (concentric: 364 .+-. 19 and 407 .+-. 24 W, respectively, and eccentric: 346 .+-. 25 and 430 .+-. 21 W, respectively). Size of the O2 deficit during the 1st min of muscular exercise is imposed by the steady-state energy requirement whatever the type of exercise. The smaller energy expenditure during this phase is probably due to less energy being released when creatine phosphate is split without resynthesis (O2 deficit) than during splitting and resynthesis of high-energy phosphate bonds (steady state).

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