Muscle coordination while pulling up during cycling.

The aim of this study was to determine the influence of the pull up action on the pedalling mechanics and muscle coordination during cycling. 9 elite cyclists pedalled at 320 watts with their preferred technique and while pulling up. The pull up action increased significantly the pedalling effectiveness during the upstroke and around the bottom dead centre. This was associated with a significant enhancement of the biceps femoris activity (48%), an earlier onset of activation of the tibialis anterior, i. e., 211 ± 83° vs. 259 ± 22° (crank angle) and a delayed offset of activation of the gastrocnemius lateralis, i. e., 244 ± 19° vs. 216 ± 39°. Consequently, co-activities between tibialis anterior and gastrocnemius lateralis muscles over 55 ± 65° (crank angle range), as well as between the biceps femoris and the tibialis anterior over 48 ± 57° were generated. These higher co-activities were necessary to stiffen the ankle joint and to power the pedal during the upstroke. Thus changes in muscle coordination improved the pedalling effectiveness during the upstroke phase but would probably lead to impairment of the oxygen consumption. Therefore, training the pull up action could be of interest to optimize this muscle coordination associated with better pedalling effectiveness by additionally relieving hip or knee extensors during the downstroke.