Meeting Abstract
86.3 Tuesday, Jan. 6 Effect of varying weight and inertia on maximum attainable running speed in humans BOWTELL, M V*; TAN, H; WILSON, A M; Royal Veterinary College; Royal Veterinary College; Royal Veterinary College mbowtell@rvc.ac.uk
Attainable running speed in humans has been presented as limited by the amount of force which can be withstood by the legs when in contact with the ground, as well as the time required to protract the legs. Increased effective weight by bend running decreases maximum running speed in a predictable manner. With force as a limiting factor it would be expected that increased body mass (and therefore increased body weight and inertia) will cause a decrease in attainable speed, but that only an increase in inertia would have no effect. In this study we independently vary weight and inertia, and therefore the demand for vertical and horizontal force.
A large horse treadmill has been adapted to allow self-selected speed running and to gain measurements of maximum attainable speed. The system uses proportional and derivative (PD) control to alter the speed of the treadmill belt dependent on the position and relative speed of the runner. Eleven participants took part in trials to test the repeatability of gaining maximum speed. Nine of these participants also took part in trials in which mass and inertia were independently varied with the addition of lead weights and by partial suspension.
We found that maximum attainable speed increased by 3.3% with 30% decreased weight (s.e.=1.4 %) and unchanged inertia but hypothesise that leg swinging quickly became limiting. We also found that unchanged weight and 30% increased inertia caused a 4.8% decrease in attainable running speed (s.e.=1.7%); both are a much smaller effect than 30% increased weight and inertia (a 15% decrease in maximum speed). This demonstrates the apparent existence of a limit to running speed that is not the direct result of effective gravity or leg swinging. Potential mechanisms will be discussed.
