The assessment of possible gender-related differences in co-contraction activity of quadriceps femoris vs. hamstring muscles in able-bodied adults, during straight walking.

Statistical gait analysis was performed on surface-EMG signals from vastus lateralis (VL), rectus femoris (RF), and medial hamstrings (MH) in 15 female (F-group) and 15 male (M-group) age-matched healthy adults. Co-contraction timing and occurrence frequency were provided. Numerous strides (around 450) were considered for each subject.

The same three co-contractions were found in F and M groups, irrespective of gender: during early stance (ES), push-off (PO) and swing (SW) phase. No relevant differences in co-contraction timing were detected between groups. An increase of occurrence frequency was observed in F-group for VL/MH co-activation during PO phase ( % vs.  % of strides,  ). Occurrence-frequency value was higher ( ) in F-group ( %) than in M-group ( %) also for RF/VL co-activation in PO phase. These differences entailed a 74.1% increase of co-contraction events in females ( ) in PO phase.

The present study provides a reference frame for knee-muscle co-contractions during walking, differentiated for women and men. The concomitant analysis of timing and frequency of co-contraction occurrences denotes a significant increase in females of QF/hamstrings co-contraction recruitment in push-off. This suggests a female attempt to augment the level of knee-joint stabilization in the final phase of single support when control of balance is thornier.