Influence of Neuromuscular Fatigue Accumulated During Training on Subsequent Chronic Adaptations: PROTECT-10 (PROTECT-10)

Physical training is based on the dose-response principle, whereby the applied load determines the resulting adaptations. However, a higher dose does not consistently lead to greater gains (Hass et al., 2000; Mitchell et al., 2012), and the precise role of neuromuscular fatigue in chronic adaptations remains a subject of debate. Some studies suggest that fatigue-specifically peripheral fatigue, which directly reflects metabolic disturbances within the muscle-serves as a key stimulus for promoting neuromuscular adaptations (Rooney et al., 1994), while others have observed no significant effect (Folland et al., 2002). These discrepancies can be attributed to several factors: the lack of precise quantification of fatigue; the failure to distinguish between central and peripheral fatigue (the latter being a critical factor) (Hureau et al., 2022); and the failure to account for differences in fatigability between men and women (Hunter, 2016). Furthermore, recent research indicates that peripheral fatigue is regulated at an individual threshold by the tone of type III-IV muscle afferents, which modulate the central motor drive to limit the accumulation of fatigue (Amann et al., 2015; Hureau et al., 2016). Gaining a better understanding of how this threshold-along with its sensitivity and potential plasticity through training-influences the adaptive response is essential for optimizing exercise prescription, both for performance and for health.