Physiological characteristics of motor units in the brachioradialis muscle across fatiguing low-level isometric contractions

摘要: The purpose of this study was to determine (i) if decomposition-based quantitative electromyography (DQEMG) could detect changes in motor unit potential (MUP) morphology and (MU) firing pattern statistics associated with muscle fatigue, (ii) any detected are correlated surface electromyographic (SEMG) signs (iii) significant fatigue-dependent repeatable within individuals. Mean MU rates the MUPs using needle electrodes during constant-torque isometric contractions held until exhaustion were investigated brachioradialis (BR) 10 healthy volunteers (mean age=28.6 yr, SD+/-3.9). Time dependant an analysis variance normalized time as a main effect. Partial correlation coefficients computed repeated measures covariance rates, needle-detected surface-detected (SMUPs) related SEMG signal amplitude frequency parameters. Intraclass (ICCs) used within-subject repeatability MUP SMUP Significant decreases mean found along increases various duration area parameters both SMUPs across fatiguing contraction. demonstrated expected fatigue: increase decrease content. significantly positively peak-to-peak voltage (r=0.85, p<0.05), (r=0.86, p<0.05). power negatively negative peak (r=-0.74, time-dependent reliably observed (ICCs 0.94 for amplitude, 0.97 0.95 ratio, voltage, 0.83 area, 0.99 0.88 area). measured their partial submaximal BR, suggest that recruitment is cause increased fatigue. We conclude DQEMG can be effectively physiological characteristics MUs accompany