Muscle warm-up affects the energy cost of exercise in humans

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Published in the Journal of Experimental Biology this research was designed by Professor Anthony J Sargeant who had a long-term interest in the effect of temperature on human muscle. The experimental work was carried out by Richard Ferguson and submitted as part of his PhD, which was jointly supervised by Derek Ball.
The study of cycling showed that warming muscle up prior to exercise actually reduces the energy cost at a fast pedalling rate (120 rev/min) but increases the energy cost at a slow pedalling rates ((60 rev/min).
Journal of Experimental Biology
J Exp Biol. 2002 Apr;205(Pt 7):981-7

Abstract The effect of elevated human muscle temperature on energy turnover was investigated during cycling exercise (at 85 % of (VO(2)max)) at a contraction frequency of 60 revs min(-1). Muscle temperature was passively elevated prior to exercise by immersion of the legs in a hot water bath (42 degrees C). During exercise at this low pedalling rate, total energy turnover was higher (P<0.

05) when muscle temperature was elevated compared with normal temperature (70.4+/-3.7 versus 66.9+/-2.4 kJ min(-1), respectively). Estimated net mechanical efficiency was found to be lower when muscle temperature was elevated. A second experiment was conducted in which the effect of elevated human muscle temperature on energy turnover was investigated during cycling exercise (at 85 % of (VO(2)max)) at a contraction frequency of 120 revs min(-1). Under the conditions of a high pedalling frequency, an elevated muscle temperature resulted in a lower energy turnover (P<0.05) compared with the normal muscle temperature (64.9+/-3.7 versus 69.0+/-4.7 kJ min(-1), respectively). The estimated net mechanical efficiency was therefore higher when muscle temperature was elevated. We propose that, in these experiments, prior heating results in an inappropriately fast rate of cross-bridge cycling when exercising at 60 revs min(-1), leading to an increased energy turnover and decreased efficiency. However, at the faster pedalling rate, the effect of heating the muscle shifts the efficiency/velocity relationship to the right so that cross-bridge detachment is more appropriately matched to the contraction velocity and, hence, energy turnover is reduced

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