Increased Co-contraction Activity During Push-Off Phase of Walking in Healthy Women

Research purpose: The assessment of possible gender-related differences in co-contraction activity of quadriceps femoris vs. hamstring muscles in able-bodied adults, during straight walking. Methods: 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. Results: 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 (21.9±13.6% vs. 11.3±8.6% of strides, p=2.5×10−3). Occurrence-frequency value was higher (p=6.9×10−3) in F-group (25.8±12.1%) than in M-group (17.3±14.2%) also for RF/VL co-activation in PO phase. These differences entailed a 74.1% increase of co-contraction events in females (p<0.05) in PO phase. Significance: 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.