PEDAL AND CRANK KINETICS IN UPHILL CYCLING

Alterations in kinetic patterns of pedal force and crank torque due to changes in surface grade (level vs. 8% uphill) and posture (seated vs . standing) were investigated during cycling on a computerized ergomet er. Kinematic data from a planar cine analysis and force data from a p edal instrumented with piezoelectric crystals were recorded from multi ple trials of 8 elite cyclists. These measures were used to calculate pedal force, pedal orientation, and crank torque profiles as a functio n of crank angle in three conditions: seated level, seated uphill, and standing uphill. The change in surface grade from level to 8% uphill resulted in a shift in pedal angle (roe up) and a moderately higher pe ak crank torque, due at least in part to a reduction in the cycling ca dence. However, the overall patterns of pedal and crank kinetics were similar in the two seated conditions. In contrast, the alteration in p osture from sitting to standing on the hill permitted the subjects to produce different patterns of pedal and crank kinetics, characterized by significantly higher peak pedal force and crank torque that occurre d much later in the downstroke. These kinetic changes were associated with modified pedal orientation (toe down) throughout the crank cycle. Further, the kinetic changes were linked to altered nonmuscular (grav itational and inertial) contributions to the applied pedal force, caus ed by the removal of the saddle as a base of support.