The use of a non-motorized treadmill for analysing sprint performance

Abstract

The measurement of human power output and anaerobic capacity in high-intensity exercise has traditionally been made using cycle ergometers. The assessment of power output during running has proved difficult because previous approaches have limited themselves to using motorized treadmills. In the present study the problems associated with motorized treadmills were overcome by using a non-motorized treadmill which was instrumented so as to allow the measurement of power output during sprint running. A non-motorized treadmill (Woodway model AB) was used because it allows rapid changes in running velocity normally found in sprinting to be monitored. In order to calculate the horizontal component of the applied power the instantaneous values of both the horizontal component of applied force and the treadmill belt speed were measured, and their product determined. A harness, attached to a force transducer, was passed around the waist securing the subject to the crossbar without restricting the movement of the limbs. The force measured was assumed to be the same as that horizontally applied to the treadmill belt. The outputs from the speed detector, force transducer and heart rate monitor were continuously monitored by a microcomputer. The results of the study showed that: (1)the peak speed attained on the treadmill is approximately 80% of that achieved in free-sprinting. (2)peak force is attained earlier than peak power and in turn peak power occurs before peak speed. (3)the force and power required to propel the treadmill belt at a constant speed increase with body weight. (4)the power required to propel the treadmill belt increases with speed. (5)stride length and frequency could be monitored. (6)elasticity in the tethering system acted as a low pass filter on the force profile.