Exercise-Induced Circulating Lactate Responses in Breast Cancer Survivors: A Systematic Review and Exploratory Meta-Analysis

Background: Physical exercise is strongly recommended for breast cancer survivors due to its beneficial effects on physical function, metabolic health, and quality of life. Lactate, traditionally considered a metabolic byproduct of glycolysis, is increasingly recognized as a signaling molecule involved in metabolic regulation and exercise adaptation. However, exercise-induced circulating lactate responses in breast cancer survivors remain poorly characterized. The aim of this systematic review and exploratory meta-analysis was to synthesize and critically appraise current evidence on exercise-induced circulating lactate responses in breast cancer survivors Methods: A systematic review and exploratory meta-analysis were conducted according to PRISMA guidelines and prospectively registered in PROSPERO (CRD42024504288). PubMed, Scopus, and Web of Science were searched to identify controlled trials investigating exercise-induced changes in circulating lactate concentrations in breast cancer survivors. Random-effects meta-analysis was performed using pooled mean differences. Results: Among 173 screened records, four studies met eligibility criteria for qualitative synthesis and three contributed to quantitative analysis. Pooled results demonstrated no statistically significant effect of exercise on circulating lactate concentrations (weighted mean difference: 0.03 mmol/L; 95% CI: −0.24 to 0.31; p = 0.81), with low heterogeneity (I2 = 31.1%). Considerable variation was observed across exercise protocols, intervention duration, and lactate assessment timing. Conclusions: Exercise-induced circulating lactate responses in breast cancer survivors appear modest and inconsistently reported across available studies. Current evidence remains limited by small sample sizes and methodological heterogeneity. These findings provide a physiological overview of lactate responses to exercise in breast cancer survivorship and highlight the need for standardized exercise interventions and metabolic outcome assessment in future research.