Sex Differences in Lower-Limb Surface Electromyographic Characteristics During Prolonged Overground Walking

This study examined sex-related differences in lower-limb surface electromyographic (sEMG) characteristics during prolonged overground walking and their sensitivity to signal processing. Publicly available recordings from 31 healthy adults (19 females, 12 males), comprising 13,465 gait cycles, were analyzed. Root mean square amplitude (RMS), peak amplitude, integrated EMG (iEMG), and stride-to-stride RMS coefficient of variation (CV) were evaluated. Raw and band-pass-filtered features were compared with filtered features normalized to the peak of each participant-side-muscle ensemble-mean walking envelope. Two channels with signal-quality concerns were excluded from the QC-screened dataset and retained in an inclusive sensitivity analysis. Mixed-effects models adjusted for height and body weight included 28 participants, contributing 278 and 280 participant-side-muscle summaries, respectively. In the QC-screened dataset, males had higher tibialis anterior (TA) and gastrocnemius lateralis (GL) peak amplitudes and higher GL RMS across all processing variants after Holm correction. The TA RMS contrast was significant only in the raw analysis; a hamstring-region peak contrast was significant only after task-reference normalization. No muscle-specific iEMG comparison survived Holm correction. Including the two excluded channels produced limited changes in TA and GL amplitude estimates, whereas CV findings were sensitive to processing and channel exclusions. Sex-related sEMG associations depended on muscle, outcome, and processing approach. Selected amplitude contrasts persisted on a task-relative scale, but these findings do not establish differences in neural drive, maximal activation capacity, or walking function. Key words Surface electromyography " Gait analysis " Sex differences " Human locomotion " Lower limb.