Peripheral artery disease and activity-induced shifts in quadriceps median frequency during treadmill walking: a preliminary study

Peripheral artery disease (PAD) is associated with altered gait biomechanics. No previous research study has investigated the effect of activity on muscle activation in individuals with PAD. The purpose of this study was to investigate the effect of PAD on muscle activation in response to a ten-minute walking task. METHODS: Ten healthy young adults, ten healthy older adults and ten individuals with PAD performed a ten-minute treadmill walking trial at a self-selected velocity. Surface EMG was recorded from the vastus lateralis and medial gastrocnemius during five steps in the first and tenth minutes of the walking trial. EMG signals were rectified and smoothed using the root mean squared (RMS) with a 20 ms smoothing window. Peak RMS EMG and median frequencies (MdF) were calculated. Mixed-model ANOVAs with Tukey’s post-hoc was used to determine effects of group and activity on peak RMS EMG and MdF. RESULTS: PAD was associated with significantly greater reductions in MdF of the vastus lateralis compared to healthy young and healthy older adults. No significant differences were observed in peak RMS EMG. DISCUSSION: PAD is associated with exaggerated rates of fatigue in the quadriceps but not the gastrocnemius. Efficacy of evidence-based therapeutic interventions should be further investigated.