Detraining Effects Following Chronic Stretching Training on Range of Motion: A Systematic Review and Meta-Analysis

Background: Stretch training can chronically increase the range of motion (ROM) of a joint. However, to date, there is still a need for a comprehensive synthesis of knowledge regarding the effects of training cessation (i.e., detraining) on ROM gains from stretching. Objectives: The purpose of this systematic review with meta-analysis was to investigate the detraining effects of stretch training on ROM. Methods: PubMed, Scopus, and Web of Science were searched. Controlled trials and randomized controlled trials with a training and a detraining phase that involved any type of stretching training, with healthy participants of all ages, were included. Risk of bias was assessed using Cochrane RoB2 and ROBINS-I tools. A meta-analysis was performed to assess effect sizes for ROM changes between pre-intervention to post-intervention, pre-intervention to detraining, and post-intervention to detraining. Additionally, the effects of potential moderators were assessed (i.e., stretching technique, duration per session, frequency per week, duration of detraining, of the training period, and type of activity performed during detraining). GRADE analysis was used to determine the quality of evidence. Results: Out of the 189 records retrieved, 13 studies with a total of 556 participants were included in this review. These studies involved stretch training programs lasting from five to 15 weeks, followed by a detraining phase ranging from two to six weeks. Risk of bias was low in 74.3–77.1% of all criteria. Confidence in cumulative evidence was high for ROM gains and low for ROM maintenance following detraining. In the studies examined stretching training induced large increases in ROM (ES = 0.93, 95% CI: 0.54–1.31, p < 0.001). A moderate higher ROM was found after a detraining period compared to pre-intervention (ES = 0.55; 95% CI: 0.33–0.77, p < 0.001), while small ROM decreases were observed from post-intervention until the end of the detraining period (ES=-0.41; 95% CI: -0.73 – -0.09, p = 0.016). Moderator analysis showed that the frequency of stretching per week significantly moderated the ROM enhancements when comparing post-intervention to detraining only, and that only active participants maintained ROM from post-intervention to detraining, while other moderators showed no significant effects. Conclusions: Chronic gains in ROM are maintained above baseline levels after stretching training cessation. However, training cessation for 2–6 weeks slightly decreases ROM compared to post-intervention levels, indicating that to maintain ROM gains over time, some form of flexibility-enhancing method should be used.