Eccentric phase duration in resistance training influences internal load and recovery dynamics, yet its specific neuromechanical effects remain unclear. This review aimed to synthesize experimental evidence from single-bout eccentric-only and eccentric-phase-tempo-manipulated resistance exercise protocols to determine how controlled eccentric-phase tempo affects acute neuromuscular fatigue, indirect markers of exercise-induced muscle damage, and short-term recovery outcomes measured from immediately post-exercise to 7 days after in healthy adults with clearly described physical activity or training status, including competitive athletes, resistance-trained individuals, and recreationally active adults when otherwise eligible. Methods: Following PRISMA 2020 guidelines, PubMed, Scopus, and Web of Science were searched from inception without language or date limits. Eligible studies were experimental trials in healthy adults with clearly reported physical activity or training status performing either eccentric-only exercise or resistance exercise in which eccentric-phase duration was explicitly manipulated and measurable. Because coupled eccentric–concentric protocols may introduce concentric fatigue, contraction structure was extracted and used as an interpretive subgroup rather than assuming all studies represented eccentric-only exercise. Studies were required to report at least one prespecified single-bout acute neuromechanical, fatigue-related, muscle-damage, or recovery outcome within 0–168 h, corresponding to the immediate to 7-day post-exercise period, after the exercise bout. Primary outcomes were maximal voluntary contraction, muscle stiffness indices, reactive strength index, delayed-onset muscle soreness, biochemical markers of damage, and muscle oxygenation within 0–168 h post-exercise. Chronic adaptations to eccentric training, such as long-term hypertrophy, strength gain, or tendon remodeling, were outside the primary scope unless studies reported eligible acute or recovery outcomes attributable to a controlled eccentric-tempo manipulation. Risk of bias was evaluated using RoB 2 or ROBINS-I, and data were summarized descriptively by tempo and time frame. Results: Seventeen studies met inclusion criteria. Explosive-to-fast eccentric conditions, corresponding to < 1 s and 1–2.9 s eccentric phases, were more often associated with greater immediate fatigue and transient performance loss, whereas moderate-to-slow eccentric conditions, corresponding to 3–5.9 s and 6–9.9 s eccentric phases, generally increased time under tension, metabolic stress, and perceived exertion. When total work or load was equalized, differences between tempos generally diminished. Overall risk of bias was moderate. Conclusions: Within the available bout-level evidence, eccentric tempo appears to modulate acute fatigue, mechanical performance, perceptual responses, and short-term recovery mainly through time-under-tension, total work, and protocol-context effects. Protocol registration: osf.io/e2598 in 04-11-2025.
Matuszczyk et al. (Sat,) studied this question.
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