Pedaling cadence effects on mechanical power and muscle contraction timing during cyclingThe mechanical energy required to propel the crank may depend on eccentric and concentric muscle actions. However, it is uncertain whether pedaling cadence would elicit changes in concentric and eccentric contributions. Therefore, the purpose of the present study was to investigate the effects of alterations in pedaling cadence on the eccentric and concentric muscle actions. Joint power production and absorption were calculated to assess potential effects from variations in pedaling cadence on joint kinetics. Twenty-one cyclists participated in this study (VO2pico: 64.1 ± 5.0 ml/kg/min; training volume: 368.2 ± 69.5 km/week). In their first session, maximal power output (POMAX) and power output related to the second ventilation threshold (POVT2) were determined during an incremental maximal cycling test to exhaustion. In their second session, cyclists performed two 2-min trials with workload from their POVT2 at two different cadences (70 and 90 rpm). Muscle activation of six muscles, pedal forces and lower limb joint kinematics were evaluated. Longer eccentric contraction at 70 rpm for vastus medialis (8%; p < 0.01) and biceps femoris (20%; p = 0.04) were observed compared to 90 rpm. Longer concentric contraction for vastus medialis muscle (10%; p = 0.04) at 90 rpm was observed compared to 70 rpm. There were no differences in joint power production and absorption among pedaling cadences. No alterations in joint power could indicate maintenance of movement when pedaling cadence is changed. Eccentric contractions from knee muscles could be related to joint control, force transmission and reduced energy cost.
EMG; Joint kinetics; Joint kinematics; Stretch-shortening cycle
