Characteristics of the electromyographic patterns of lower limb muscles during gait in patients with Parkinson's disease when OFF and ON L-Dopa treatment

The purpose of this study was to compare the electromyographic (EMG) behavior of the triceps surae (TS), tibialisanterior (TA), quadriceps and hamstring muscles of the lower limbs during self-initiated free gait in a group ofpatients (n = 15) with Parkinson's disease (PD), when OFF and ON L-Dopa, with that of normal controls. When OFFL-Dopa, we observed qualitative disturbances in muscle activation patterns, such as an absence or extreme reductionin TA activations in early stance or during the early and late swing phases. Other disturbances included flatter profilesof the TS activation burst at push off, and temporal alterations that included prolonged activation of the proximalmuscles during the stance phase. Statistical analysis showed that the TA was the most affected muscle in most of thepatients particularly during the activation burst in late swing (p <.0004). After medication (ON L-Dopa), theamplitude and timing of distal muscle activations became more similar to normal values, with the increase in EMGamplitude being dramatic in some patients. In the proximal muscles, the effects on EMG amplitude were less markedand prolonged activation often persisted even after the administration of L-Dopa.