Lactic acid assessment in post-stroke hemiparetic subjects following electrical stimulation for muscle strengthening

Abstract

Strengthening paretic muscles improves functional capacity, which can be achieved by functional electric stimulation (FES), but specific parameters are needed in order to prevent muscle fatigue. The purpose of this study was to assess, in post-stroke hemiparetic patients, the necessary time of rest (time off) for re-absorption of lactic acid during FES, so as to prevent fatigue - detected by lactic acid testing. Blood samples of 18 hemiparetic subjects were collected at seven moments: pre-treatment rest, after each of three series of 15 repetitions stimuli, and at the third, sixth, and ninth minutes following therapy session. Electrical, two-phase pulses at 50 Hz were applied, 10 seconds on and 10 seconds off (protocol 1), and 10 seconds on and 30 seconds off (protocol 2), on the motor point of tibialis anterior muscle. The blood sample analysis showed no statistically significant differences (p>;0.05) between protocols 1 and 2; neither could differences be found at immediate post-session measures. It may thus be said that the measuring tool here employed to infer fatigue did not prove efficient to detect it, therefore preventing the assessment of the ideal time of rest (time off). Thus a continuity of this study is suggested, with changes in the muscle and the functional activity elicited by electric stimulation, and relying on an alternative tool for measuring and detecting muscle fatigue.