Low-level activity of the trunk extensor muscles causes electromyographic manifestations of fatigue in absence of decreased oxygenation

The effect of work pace on workload, motor variability and fatigue during simulated light assembly work

“…In another study, Falla and Farina (2007) showed that such changes in the spatial distribution of electromyography could be triggered by short increases in muscle loading, consistent with earlier studies indicating that short bursts of activity on top of an isometric contraction may stimulate motor unit substitution (Westad et al 2003). A recent study by van Diee¨n et al (2009) …”

An EMG frequency-based test for estimating the neuromuscular fatigue threshold during cycle ergometry

“…In particular, it has been reported that fatigue-induced decreases in EMG frequency were not related to oxygen supply or pH status of the working muscle (van Dieën et al 2009). Specifically, van Dieën et al (2009) found decreases in EMG MPF during low-level (2 and 5% MVC) isometric contractions in the absence of changes in muscle tissue oxygenation or changes in EMG amplitude, and concluded that increased levels of interstitial [K ? ], not lactate accumulation, likely underlie the changes in EMG MPF.…”

“…Thus, according to some previous studies (Lindstrom et al 1970;Moritani et al 1982), changes in intracellular pH account for the fatigue-related increases in EMG amplitude and decreases in MPF. Recent studies (Fortune and Lowery 2007;Juel 1988;van Dieën et al 2009), however, have indicated that factors other than lactate accumulation and decreased pH may cause fatigue. In particular, it has been reported that fatigue-induced decreases in EMG frequency were not related to oxygen supply or pH status of the working muscle (van Dieën et al 2009).…”

“…Recent studies (Fortune and Lowery 2007;Juel 1988;van Dieën et al 2009), however, have indicated that factors other than lactate accumulation and decreased pH may cause fatigue. In particular, it has been reported that fatigue-induced decreases in EMG frequency were not related to oxygen supply or pH status of the working muscle (van Dieën et al 2009). Specifically, van Dieën et al (2009) found decreases in EMG MPF during low-level (2 and 5% MVC) isometric contractions in the absence of changes in muscle tissue oxygenation or changes in EMG amplitude, and concluded that increased levels of interstitial [K ?…”

The effect of muscle fatigue and low back pain on lumbar movement variability and complexity

“…Recruitment variability, of both motor units and muscles, have a bearing on endurance during both sustained and intermittent isometric contractions of the corresponding muscles. This has been observed in trunk (van Dieen et al, 2003, van Dieen et al, 2009, and shoulder muscles (Falla et al, 2007, Farina et al, 2008, Palmerud et al, 1998. One unresolved question is whether these adaptations to fatigue are hampered by the presence of pain, as an impaired adaptation to fatigue might augment the development of musculoskeletal disorders.…”