Distal muscle activity alterations during the stance phase of gait in restless leg syndrome (RLS) patients

ObjectiveTo assess if there is a circadian variation in electromyographical (EMG) muscle activity during gait in restless legs syndrome (RLS) patients and healthy control participants.MethodsGait assessment was done in 14 RLS patients and 13 healthy control participants in the evening (PM) and the morning (AM). Muscle activity was recorded bilaterally from the tibialis anterior (TA), lateral gastrocnemius (GL), rectus femoris (RF) and biceps femoris (BF) muscles.ResultsA circadian variation during the stance phase in only TA (PM > AM, p < 0.005) and BF (PM < AM, p = 0.008) activity was observed in control participants. Conversely no circadian variation was seen in any muscles in the RLS patients. RLS patients had an increased TA and GL activity (RLS > Controls, p < 0.05) during early stance and decreased GL activity (RLS < Controls, p < 0.01) during terminal stance in comparison to control participants in the evening. No other significant differences were noted between RLS patients and control participants. Activation of GL during the swing phase was noted in 79% of RLS patients and in 23% of control participants in the morning compared to 71% and 38% in the evening, respectively.ConclusionEMG muscle activity shows no circadian variation in RLS patients. Evening differences in gait muscle activation patterns between RLS patients and control participants are evident. These results extend our knowledge about alterations in spinal processing during gait in RLS. A possible explanation for these findings is central pattern generator sensitization caused by increased sensitivity in cutaneous afferents in RLS patients.