Acute fatigue and recovery responses to resistance training performed to momentary muscular failure: an exploratory multimodal physiological study

This study compared the effects of a full-body resistance training session performed to momentary muscular failure (RTF) or non-failure (RTNF) on mechanical, perceptual, metabolic, neuromuscular, cardiovascular, and autonomic responses in trained men. In a randomized crossover design, six men (25.5 ± 3.3 years; 77.8 ± 6.2 kg; 174.5 ± 5.1 cm) completed two sessions of six exercises. RTF sets were performed to failure at 100% 10-repetition maximum (10RM), while RTNF sets consisted of 10 repetitions at 85% 10RM. Perceptual, metabolic, hormonal, cardiovascular, and autonomic responses, alongside markers of tissue damage and neuromuscular function, were monitored for 72 h post-RT. Data were analyzed via Generalized Estimating Equations. RTF induced greater perceived exertion (p < 0.001) with fewer repetitions per set and reduced volume in specific movements (p < 0.05), despite similar total session volume (p > 0.05). RTF elicited higher lactate (p = 0.003) and cortisol (p < 0.001). RTF exacerbated tissue damage markers (creatine kinase and lactate dehydrogenase, p < 0.001) and soreness (p < 0.05), leading to delayed countermovement jump recovery (p < 0.001) through 72 h. Conversely, RTNF demonstrated faster perceived recovery (p < 0.001) and similar autonomic preservation (p > 0.05). Acute cardiovascular strain was higher in RTF (p < 0.05), with no residual effects. Although the small sample size warrants cautious interpretation of inferential statistics, RTF delays recovery without acute functional benefits. Since proximity-to-failure drives physiological stress, RTNF proves to be more efficient and sustainable.