Torque-velocity relationship during cycle ergometer sprints with and without toe clips

Abstract

The torque-velocity relationship in cycling has been studied during all-out sprints (n = 6 subjects) with and without toe clips on an electronic Lode ergometer with strain gauges, to estimate the importance of the expected decrease in torque, velocity and power output. As previously found with different cycling protocols, the torque-velocity relationship was linear for all-out sprints with toe clips. A similar relationship was observed when cycling without toe clips but the torque-velocity relationship was inflected downwards at low or high velocities in several subjects who were not regular cyclists. The pulling action during the rise of the pedal at low velocities cannot explain why the torque-velocity relationship is not hyperbolic for cycling exercises with toe clips because similar relationships were observed without toe clips. The maximal power output was significantly higher during cycling with toe clips (782 W vs 668 W, P < 0.05), probably because of the pulling action at low and medium velocities as indicated by the higher value of the extrapolated maximal torque T ₀ (138 N · m vs 122 N · m, P<0.05). In contrast, the maximal extrapolated velocity, V ₀ and peak velocity were not significantly improved by the use of toe clips. The comparison of the angle-torque patterns at low and high velocities suggested that the kinetic energy of the legs can be transformed into power output when cycling without toe clips as well as it can when cycling with toe clips.