Is Exercise-Induced Lactate Accumulation Associated with Changes in Acylated Ghrelin? A Systematic Review and Individual Participant Data Meta-analysis

Introduction: Lactate has been proposed to suppress the release and activation of the orexigenic peptide acylated ghrelin, though no study has synthesized available evidence from acute exercise trials. Purpose: To determine if exercise-induced lactate accumulation predicts and/or is associated with changes in acylated ghrelin. Methods: A systematic search strategy was developed and conducted in four databases for studies exploring changes in acylated ghrelin and lactate during acute exercise interventions. Using Covidence, studies were identified and included if participants were between the ages of 18 and 65 y, healthy (absence of medical condition or disease), conducted an acute exercise trial, and measured both acylated ghrelin and lactate pre- and post-exercise. Corresponding authors of eligible studies were contacted for individual data and linear mixed-effect models were fitted and repeated measures correlations were conducted to determine if change in (Δ) lactate predicts and/or was associated with Δ acylated ghrelin and acylated ghrelin incremental area under the curve (iAUC). Results: Twelve data sets (169 participants) were included in the Δ acylated ghrelin analysis and nine data sets (105 participants) were included in the acylated ghrelin iAUC analysis. There was a significant effect of Δ lactate for both Δ acylated ghrelin (β=-8.1, SE=1.1, p<0.001) and Δ acylated ghrelin iAUC (β=-698, SE=69, p<0.001) and Δ lactate had a negative correlation with both outcomes (r m =-0.41, p<0.001; and r m =-0.59, p<0.001). Conclusions: Overall, this study suggests that exercise-induced lactate accumulation significantly affects Δ acylated ghrelin and acylated ghrelin iAUC and is negatively associated, suggesting greater exercise-induced lactate accumulation would be associated with the suppression of ghrelin.