In order to calculate mechanical efficiency during human exercise the total power generated needs to be known. That is the external power delivered to some ergometer plus the internal power required to move the limb. This research carried out in Copenhagen in collaboration with Jens Bangsbo and Per Aagaard addresses this problem. The research publication formed part of the PhD thesis of Richard Ferguson which work was directed by Derek Ball and Professor Anthony J Sargeant.
Total power output generated during dynamic knee extensor exercise at different contraction frequencies
Journal of Applied Physiology
J Appl Physiol. 2000 Nov;89(5):1912-18
A novel approach has been developed for the quantification of total mechanical power output produced by an isolated, well-defined muscle group during dynamic exercise in humans at different contraction frequencies. The calculation of total power output comprises the external power delivered to the ergometer (i.e., the external power output setting of the ergometer) and the “internal” power generated to overcome inertial and gravitational forces related to movement of the lower limb. Total power output was determined at contraction frequencies of 60 and 100 rpm. At 60 rpm, the internal power was 18+/- 1 W (range: 16-19 W) at external power outputs that ranged between 0 and 50 W. This was less (P<0.05) than the internal power of 33+/-2 W (27-38 W) at 100 rpm at 0-50 W. Moreover, at 100 rpm, internal power was lower (P<0.05) at the higher external power outputs. Pulmonary oxygen uptake was observed to be greater (P<0.05) at 100 than at 60 rpm at comparable total power outputs, suggesting that mechanical efficiency is lower at 100 rpm. Thus a method was developed that allowed accurate determination of the total power output during exercise generated by an isolated muscle group at different contraction frequencies