Left Ventricular Mass Following Detraining In Endurance Trained Individuals: Systematic Review And Meta-analysis

Abstract

Exercise training has been shown to cause unique cardiac adaptations, such as increases in left ventricular (LV) mass. Detraining or cessation of training reportedly decreases LV mass, however this has not been systematically evaluated. Furthermore, the dose-response relationship between cardiac dimensions and detraining is unknown. Purpose: This investigation aimed to systematically review the literature and conduct a meta-analysis to assess the impact of detraining on LV mass in endurance trained individuals. Methods: A literature search of prospective detraining studies was conducted using electronic databases (eg. EMBASE & MEDLINE). Inclusion criteria comprised those who were adults, endurance trained, detrained for at least one week, and findings that reported changes in LV mass. In studies that assessed LV mass at multiple time points, we used final time points in the meta-analysis. The association between the changes in LV mass and detraining was calculated using a pooled statistic for random effects; statistical significance was set at p < 0.05. Study quality was assessed by two reviewers using a modified version of the National Institute of Health (NIH) quality assessment tool. Results: Thirteen studies with a total of 189 participants (ages 18-55, 15% female) satisfied the inclusion criteria, each with various detraining programs lasting from 1.42-15 weeks. The meta-analysis revealed a significant decrease in LV mass following detraining (standardized mean difference = -0.710, 95%CI = -.874 - -0.546, p > 0.001). Changes in LV mass were not associated with length of the detraining period which appears to stabilize over detraining blocks longer than 2 weeks. Mean change in LV mass did not differ according to training level. Study quality was rated poor to fair, with inconsistent participant details and varying workloads during detraining (i.e., reduced frequency of training vs. no exercise). Conclusion: LV mass decreases as a result of detraining in healthy, endurance-trained individuals, and appears to be unaffected by length of the detraining period or training history /athlete status. Study findings are limited due to poor to fair study quality and lack of female participants. Further investigations are warranted to understand the impact of detraining on cardiac structure in healthy individuals.