The change of activation pattern in different stages of PD - importance of proximal muscle exercise

초록

Background: In the progression of Parkinson disease (PD), gradual derangement of the usage of lower extremity muscles are disabling. Therapeutic exercises has been effective on the mobility and balance. But the change of muscle activation pattern with progression of PD might give important information for therapeutic exercise implementation. Objective: The purpose of this study was to investigate the activation of lower-extremity muscles according to Hoehn-Yahr scale during gait. Patients and methods: Thirty six PD patients (Hoehn and Yahr stage 1; 13, 63.1±7.8, stage 2; 15, 67.1±6.4, stage 3; 8, 63.7±8.7) participated in this study. Gait analysis was done with GAITRite system. We recorded EMG signals in tibialis anterior (TA), medial gastrocnemius (MG), soleus (SOL), rectus femoris (RF), and biceps femoris (BF) muscles using Noraxon 16 channels EMG system during walking at preferred speed. Rectified EMG signals were normalized to reference voluntary contractions (RVC) over a gait cycle at the preferred speed. Results: In whole gait cycle, distal muscle group (TA, MG, SOL) showed similar patterns between H&Y stages. But in proximal muscle group (RF and BF) showed gradual changes without significance (p>0.05). And in specific gait cycle analysis, TA showed gradual attenuation throughout H&Y stages, but MG showed gradual increment in preswing phase (p<0.05). The side to side difference in whole gait cycle showed difference in proximal muscles and SOL (p<0.05). The proximal muscles (RF, BF) showed significant changes of activity in swing phase. Conclusion: The side to side difference of muscle activity were greater in proximal muscles (RF, BF) with progression of PD stages. The inter-limb co-ordination reduction might cause increment of risk of falling. The proximal muscle intervention might be more useful for exercise rehabilitation for the efficient gait and prevention of falling.