Systematic review and meta-analysis of the acute effects of self-selected rest intervals on exercise performance maintenance, lactate levels, and heart rate.

Clinical Snapshot

Key Findings

• P Value: Performance (overall): p = 0.29; Performance (post-outlier removal): p < 0.01; Heart rate: p = 0.98; Blood lactate: p = 0.36

• Effect Size: Hedges' g = 0.27 (overall, non-significant); g = 0.20 (post-outlier removal, significant). Heart rate: g = 0.002 (non-significant). Blood lactate: g = -0.20 (non-significant). All effect sizes are small by conventional benchmarks (Cohen's d < 0.5).

• Primary Outcome: Exercise performance maintenance: No significant overall difference between self-selected and fixed rest intervals (g = 0.27, 95% CI [-0.14, 0.69], p = 0.29). After outlier removal, a small but statistically significant effect favouring self-selected rest intervals was identified (g = 0.20, 95% CI [0.08, 0.33], p < 0.01).

• Nnt Or Sensitivity: No NNT calculable from available data. Effect sizes are small (Hedges' g ≤ 0.27), suggesting limited clinical magnitude even where statistical significance is achieved post-outlier removal. No sensitivity/specificity or hazard ratio applicable to this intervention review.

• Confidence Interval: Performance (overall): 95% CI [-0.14, 0.69]; Performance (post-outlier removal): 95% CI [0.08, 0.33]. CIs for heart rate and blood lactate not fully reported in abstract.

Clinical Application

Self-selected rest intervals are inherently low-cost and require no additional equipment, making them practically feasible in gym, rehabilitation, and community exercise settings. Implementation requires practitioners to shift from prescriptive to individualised rest period models, which may require education and monitoring frameworks. The approach aligns with person-centred care principles but lacks sufficient evidence to replace standardised protocols. In the Australian context, exercise prescription is guided by ESSA (Exercise and Sports Science Australia) standards and RACGP physical activity guidelines. Self-selected rest intervals are not currently a formally recommended strategy in Australian clinical exercise physiology or sports medicine guidelines. The findings are insufficient to prompt a change in RACGP or ESSA recommendations. For accredited exercise physiologists (AEPs) working under Medicare-funded chronic disease management plans, individualised rest interval prescription may be conceptually aligned with person-centred care but requires stronger evidence before formal adoption. No TGA or PBS implications are relevant to this non-pharmacological intervention. Australian sports science practitioners should monitor this emerging literature but should not alter current evidence-based rest interval protocols based on this review alone. Healthy adults undertaking acute resistance or high-intensity exercise sessions where rest interval prescription is relevant. Potentially applicable to recreational athletes, competitive sports populations, and exercise rehabilitation settings. Generalisability is limited by the small, poorly characterised sample across included studies.

Abstract

BACKGROUND: Rest interval duration is a key variable in exercise prescription, influencing both performance and physiological responses. Traditional training typically employs fixed rest intervals; however, this approach may not adequately reflect individual variability in recovery needs. Recently, self-selected rest intervals-based on individual perception-have gained attention as a potential strategy for more precise load regulation. Nevertheless, current evidence regarding their effects on exercise performance, heart rate, and blood lactate remains inconsistent. METHODS: This study followed PRISMA guidelines and conducted a systematic search of Web of Science, PubMed, Cochrane Library, and Embase from database inception to March 20, 2026. Acute experimental studies comparing self-selected and fixed rest intervals were included. A three-level random-effects meta-analysis was performed to account for dependency among multiple effect sizes. Subgroup analyses, meta-regression, and sensitivity analyses were conducted to explore potential moderators and assess robustness. RESULTS: Sixteen studies (k = 16) involving 281 participants were included. No significant overall difference was observed between self-selected and fixed rest intervals for exercise performance (g = 0.27, 95% CI [-0.14, 0.69], p = 0.29), with substantial between-study heterogeneity. After removing outliers, a small but significant effect favoring self-selected rest intervals was identified (g = 0.20, 95% CI [0.08, 0.33], p < 0.01). No significant differences were observed for heart rate (g = 0.002, p = 0.98) or blood lactate (g = -0.20, p = 0.36). CONCLUSION: Self-selected and fixed rest intervals produce comparable effects on exercise performance and physiological responses. However, self-selected rest intervals may confer a small advantage in maintaining performance under specific conditions. These findings should be interpreted with caution due to sensitivity to outliers and study heterogeneity.

References

1. 1.Lv, L., Chen, C., Liu, X., Liu, H., & Wu, P. (2026). Systematic review and meta-analysis of the acute effects of self-selected rest intervals on exercise performance maintenance, lactate levels, and heart rate. PLOS ONE. https://doi.org/10.1371/journal.pone.0354594