Fig. 9. Example of the time course of enthalpy output from a muscle performing 40 (circles) and 60 (diamonds) realistic contractions at 2 Hz. Isometric contraction was 15 % of the cycle duration, while shortening and lengthening phases accounted for 35 % and 50 % of the cycle duration respectively. Data points represent the mean enthalpy output per cycle averaged over five successive cycles. The horizontal position of each data point corresponds to the middle of the cycles over which the mean values were calculated.