Beyond the pump: a narrative review of the acute molecular, metabolic, and neuropsychological responses to a bout of resistance exercise

Background Resistance training is widely recognized for its chronic adaptations, including strength, muscle hypertrophy, and improvements in musculoskeletal health. However, a single bout of resistance exercise also elicits a range of acute physiological and psychological responses across multiple systems. These immediate responses have generally been examined within individual physiological domains, with less attention given to their coexistence and temporal overlap following a single session. Methods This narrative review synthesizes evidence relating to the acute systemic effects of a single bout of resistance exercise. Literature was identified through iterative searches of electronic databases and reference lists, with emphasis on primary human studies directly examining acute responses, alongside relevant systematic reviews, meta-analyses, and mechanistic literature. Results Acute resistance exercise induces responses across endocrine and myokine, metabolic, vascular, pain-related, psychological, cognitive, and sleep-related domains. Contracting skeletal muscle releases myokines and other signalling molecules with potential systemic actions. Post-exercise energy expenditure and muscle protein synthesis may remain elevated during recovery, while glucose uptake and insulin sensitivity are enhanced. Acute resistance exercise can also produce exercise-induced hypoalgesia, reduce state anxiety, improve aspects of executive function and cognitive performance, and may influence sleep continuity and neurophysiological activity. These responses differ in their evidential basis and physiological significance, encompassing directly observed short-term effects, proposed regulatory mechanisms, and more tentative hypotheses regarding longer-term implications. Conclusion A single bout of resistance exercise produces temporally overlapping responses across multiple physiological and psychological systems. These responses should not be assumed to represent adaptive remodelling or direct mechanisms of chronic health benefit. Nevertheless, integrating them provides a broader perspective on the immediate multisystem consequences of resistance exercise and may help inform future research examining how repeated acute responses relate to longer-term adaptation and health outcomes.