A note on stability in force applied to control a repetitive task with the legs

The forces applied to pedals during cycling were collected every 40 ms from approximately 29,000 movement repetitions. Intra-cycle mean values of force and its variability were significantly correlated, supporting Schmidt's impulse variability theory of within-movement activities of the legs. In addition, as mean forces approached peak values, coefficients of variation decreased. From averages taken minute by minute, intra-cycle forces were seen to rise or fall in concert, implying that the pattern as a whole constituted a significant neuro-muscular unit of control.