Muscle recovery from a short fatigue test and consequence on the reliability of EMG indices of fatigue

Abstract

The purpose of the present study was to evaluate if rest intervals of 10 or 15 min allow the back muscles to recover completely, from an electromyographic (EMG) point of view, after performing a fatiguing contraction. Twelve healthy males stood in a dynamometer with the trunk in a vertical position and performed three trunk extension fatiguing trials (30 s contractions sustained at 75% of the maximal voluntary contraction) separated successively by a 15 min (between trial 1 and 2) and a 10 min (between trial 2 and 3) rest period. The EMG signals from four pairs of back muscles were collected at 2,048 Hz with active surface electrodes. Different EMG indices computed from the temporal and frequency domains of the EMG signal were considered to evaluate muscular fatigue and recovery from trial 1 to trial 2 and from trial 2 to trial 3. No significant differences (one-way ANOVAs between the three trials, alpha=0.05) were obtained for the different EMG indices computed. The percentage of variance explained by the inter-trial effect was none in most cases, corroborating that no systematic error was present between the trials and suggesting that complete muscle recovery was allowed with 10 or 15 min rest periods. These results support the use of rest periods of 10 to 15 min between multiple fatigue tests, at least for back muscles and for high intensity short duration fatigue tasks as the one used in the present study.

Muscle Fatigue Estimation in Repetitive Lifting Task Using Surface Electromyography-Based Analysis

“…This finding was in good agreement with previous, in frequency domain, studies which had hypothesized that decrease in median frequency signifies onset of muscle fatigue and was associated with the negative slope of the regression line [24][25][26][27]. Unlike our frequency domain analysis, other investigators used different approaches, such as time domain analysis, found that fatigue occurred when time domain parameters such as mean amplitude and root mean square (RMS) amplitude increased [28,29]. In those studies, positive slopes, of time domain parameters, signified the fatigue rates [26,30].…”

Comparação da fadiga eletromiográfica dos músculos paraespinhais e da cinemática angular da coluna entre indivíduos com e sem dor lombar

“…O decréscimo da freqüência mediana para baixas freqüências de espectro reflete a fadiga periférica de fibras do tipo II (12) . De acordo com Larivièri et al (14) , Kramer et al (7) e Oddsson et al (24) a compressão do espectro para baixas freqüências é devido ao acúmulo de ácido lático, íons H + no sarcolema e o aumento na concentração do íon K + na fibra muscular (7,14) . Esta mudança de concentração de íons faz com que ocorra uma alteração na excitabilidade da membrana das células musculares.…”

“…O declínio da FM durante contrações fatigantes é considerado como medida objetiva do processo de fadiga muscular (4,7) . Alguns estudos verificaram a análise espectral dos músculos parespinhais em indivíduos com e sem dor lombar em posturas estáticas e dinâmicas (10,12,14,15) . Estes estudos avaliam a fadiga dos músculos na posição ortostática ou em prono ao invés da posição sentada que é comum em atividades ocupacionais, tem melhor fixação da pelve, menos compensações e simula situações do cotidiano (16) .…”

Effectiveness of low-frequency vibration recovery method on blood lactate removal, muscle contractile properties and on time to exhaustion during cycling at VO2max power output

“…This recovery period was applied since as previous studies reported, complete muscle recovery can be achieved with 10-15 min rest periods (Lariviere et al 2003). In addition, P-rec strategies used for less than 10 min are insufficient to reproduce the maximal voluntary contraction (Esposito et al 1998;Seiler and Hetlelid 2005).…”