Influence of physical post-exercise recovery techniques on vagally-mediated heart rate variability: A systematic review and meta-analysis

In sports, physical recovery following exercise‐induced fatigue is mediated via the reactivation of the parasympathetic nervous system (PNS). A noninvasive way to quantify the reactivation of the PNS is to assess vagally‐mediated heart rate variability (vmHRV), which can then be used as an index of physical recovery. This systematic review and meta‐analysis investigated the effects of physical recovery techniques following exercise‐induced fatigue on vmHRV, specifically via the root mean square of successive differences (RMSSD). Randomized controlled trials from the databases PubMed, WebOfScience , and SportDiscus were included. Twenty‐four studies were part of the systematic review and 17 were included in the meta‐analysis. Using physical post‐exercise recovery techniques displayed a small to moderate positive effect on RMSSD ( k = 22, Hedges' g = 0.40, 95% confidence interval [CI] = 0.20–0.61, p = 0.04) with moderate heterogeneity. In the subgroup analyses, cold water immersion displayed a moderate to large positive effect ( g = 0.75, 95% CI: 0.42–1.07) compared with none for other techniques. For exercise type, physical recovery techniques performed after resistance exercise ( g = 0.69, 95% CI: 0.48–0.89) demonstrated a larger positive effect than after cardiovascular intermittent ( g = 0.52, 95% CI: 0.06–0.97), while physical recovery techniques performed after cardiovascular continuous exercise had no effect. No significant subgroup differences for training status and exercise intensity were observed. Overall, physical post‐exercise recovery techniques can accelerate PNS reactivation as indexed by vmHRV, but the effectiveness varies with the technique and exercise type.