The Medial-Lateral Pedal Force Component Correlates with Q-Angle during Steady-State Cycling at Different Workloads and Cadences

Leg movement during cycling is constrained to the pedal/crank path and predominantly occurs in a sagittal plane. Medial-lateral force (FML) applied to the pedals is considered as a waste and does not contribute to the pedaling. The aim of this study was to examine the changes in FML across different cadences and workloads, and to examine the correlation with lateral knee movement (Q-angle). Twenty-two cyclists completed six trials at three workloads (2, 2.5 and 3 W/kg) and three cadences (75, 85, 95 rpm). Forces were recorded from the force pedal mounted to the left side. Absolute and normalized (to the peak total force) FML were compared across conditions and cross-correlation with Q-angle was calculated. Absolute FML was significantly different across cadences and workloads (p < 0.05) with higher absolute FML at higher cadence. There was no significant difference in normalized FML across the three cadences. There was a significant decrease in normalized FML (similar to 10 N) at higher workloads. Statistically significant correlations were found between the FML and Q-angle (R = 0.70-0.77). The results demonstrate the link between the FML and Q-angle in healthy pain-free cyclists during stationary cycling. It has also been observed that smaller normalized magnitude of the FML is present when the force effectiveness is increased.