Du, C, Xu, H, Shi, J, Wei, J, Quan, H, and Zhu, T. Internal load and fatigue characteristics in male cross-country skiers during summer training. J Strength Cond Res XX(X): 000-000, 2026-This study aims to measure the internal load and fatigue responses of cross-country skiers during a 3-week summer training period, comparing differences across various training methods and their combinations. Twelve male cross-country skiers participated in this longitudinal observational study. We recorded the internal load for each training session via Firstbeat sport devices on the basis of the Banister training impulse (bTRIMP) model. The fatigue assessment metrics included the resting heart rate (RHR) and quick recovery test percentage (QRT%). Physiological performance was assessed by measuring maximal oxygen consumption (V̇o2max). Statistical significance was considered at p 0.05). However, the postcompetition QRT% was significantly lower than the post-training value (p 0.05). A moderate negative correlation was observed between RHR and QRT% (r = -0.361, p 0.05). Overall, although there was considerable variation in the internal load across different types of sessions, no significant cumulative signs of fatigue were detected.
Du et al. (Thu,) studied this question.