Passive heating and neuromuscular function: Acute and chronic adaptations, thermal strain responses, and translational implications

This review synthesized the evidence on the acute and repeated effects of passive heating on neuromuscular function, with particular emphasis on the interaction between central and peripheral thermal load. Following a literature search, 30 studies were selected investigating acute responses and 10 studies examining repeated passive heating interventions. Acutely, passive heating exerts dual and, at times, opposing effects on neuromuscular function. Increases in muscle temperature enhance contractile function, particularly during electrically evoked contractions and rapid voluntary actions, whereas elevations in core temperature can transiently impair maximal voluntary contraction through reductions in central neural drive. However, the influence of hyperthermia on submaximal contractions remains less clear. Although these responses are consistently reported, the minimum or optimal thermal stimulus required to induce neuromuscular adaptations has not been established. Current evidence suggests that cumulative thermal load, rather than peak muscle or core temperature alone, provides a more informative framework for interpreting these responses. Repeated passive heating appears to induce both peripheral and central adaptations when sufficient muscle and core thermal loads are achieved, improving maximal voluntary contraction, rapid force production, and walking performance in sedentary individuals, older adults, and clinical populations. Collectively, these findings support passive heating as a promising nonpharmacological strategy to enhance neuromuscular performance. However, the available literature remains dominated by healthy young men and laboratory-based isometric and isokinetic assessments. Future research should investigate sex-specific responses, more diverse populations, and task-specific neuromuscular outcomes relevant to activities of daily living, occupational function, and sport-related performance.