Comment on 'a model for the calculation of mechanical power during distance running'.

Because widely varying estimates of mechanical power have been calculated for a given speed of running by previous investigators, the effects of various assumptions necessary for mechanical power calculations were evaluated via a segmental energy analysis using 3-D cine data from 31 well-trained subjects running overground at 3.57 ms-1. The magnitude of power calculated was very dependent upon assumptions involving the amount of between segment energy transfer occurring, the relative metabolic cost of positive vs negative work, the amount of the total negative work attributed to muscular work, the effects of elastic storage of energy and on the choice of cutoff frequency in filtering the coordinate data. Mechanical power values ranged from 273 to 1775 W depending on the particular assumptions made and computational methods employed giving efficiency ratios from 0.31 to 1.97. These results point to a need for more definitive research into the role played by energy transfer, negative work, and elastic storage of energy before confidence in measured mechanical power can be established.