The influence of peripheral arterial disease on lower limb surface myoelectric signals in patients living with Type II Diabetes Mellitus

Abstract

Aim: The aim of this study was to evaluate whether there are any significant differences in muscle activity between individuals living with type II diabetes mellitus (DM) and individuals living with type II DM and peripheral arterial disease (PAD), during gait, at a self-selected speed and at various gait transition speeds. The influence of different stages of PAD on muscle activity during gait was also assessed with the use of surface electromyography. Research Design and Method: A prospective, comparative, non-experimental study was conducted. Ninety participants were divided into three groups namely Group A (thirty participants living with type II DM), Group B(i) (thirty participants living with type II DM and mild PAD) and Group B(ii) (thirty participants living with type II DM and severe PAD). Surface electrode sensors were placed according to SENIAM guidelines, on six lower limb muscles on both limbs, namely, rectus femoris, biceps femoris, tibialis anterior, medial head of gastrocnemius, peroneus longus and extensor hallucis longus. Muscle activity was recorded using a 16-channel Trigno™ Wireless System by Delsys®, where participants were instructed to walk at a self-selected speed on a 10-m walkway. This procedure was repeated at 5% and 10% above the step frequency using a digital metronome. The raw data was transferred to Delsys EMGworks® Analysis software to be processed and analysed. Averaged Burst RMS was used to analyse the amplitude (mV) and the duration of muscle activation (s) of each signal. Results: There was a significant increase in muscle amplitude and duration of activation in the presence of lower limb ischaemia during gait at a self-selected speed and at 5% and 10% above the baseline step frequency. The largest significant difference (p = < 0.05) in EMG amplitude and duration of activation when looking at the six muscles in general was found between participants living with Type II DM [Group A] and participants living with Type II DM and severe PAD [Group B(ii)]. No significant difference was found between baseline step frequency, 5% above the baseline step frequency (Speed 2) and 10% above the baseline step frequency (Speed 3) in the mean EMG muscle amplitude and duration of activation in all six muscles tested. Conclusion: The findings in this study show that there was an increase in muscle EMG amplitude and duration of activation in individuals living with PAD during gait. This indicates that there are musculoskeletal and biomechanical changes in the lower limb musculature with increasing severity of PAD. Higher muscle exertion demands are required during gait to produce the desired action which may result in earlier fatigue. Electromyographic tests in the clinical setting would be beneficial for detecting muscle dysfunction objectively and noninvasively, even during early stages of the disease, thus reducing the risk of lower limb complications associated with type II DM and PAD.