Heart rate‐based indices to detect parasympathetic hyperactivity in functionally overreached athletes. A meta‐analysis

Abstract

Investigations into the sensitivity of heart rate-(HR) derived indices for tracking parasympathetic nervous system (PNS) changes in functionally overreached (F-OR) endurance-trained athletes have produced equivocal findings. Lack of clarity may be a result of methodological inconsistencies. Therefore, the aims of this systematic review and meta-analysis were (a) to determine the sensitivity of resting and post-exercise vagal-related HR variability (HRV) and HR recovery (HRR) indices to detect PNS modulation in F-OR and non-overreached (non-OR) athletes, and (b) to investigate the influence of methodological factors on the sensitivity of HR-based indices to detect PNS hyperactivity in F-OR athletes. We searched CENTRAL, Scopus, PubMed, Embase, and Web of Science up to May 2020 for the following terms: male and female endurance-trained athletes, controlled and uncontrolled studies that carried out an overload training period, and PNS modulation measured in resting and post-exercise, pre-and post-overload training period. A random-effects model of standardized mean difference (SMD) was estimated for each outcome measure based on the training-induced fatigue status (F-OR vs non-OR athletes), and the influence of methodological issues to detect PNS hyperactivity in F-OR was assessed by subgroup analyses. Pooled analysis showed that resting vagal-related HRV indices did not detect PNS hyperactivity in F-OR athletes (SMD + = −0.01; 95% confidence interval [CI] = −0.51, 0.50), and no statistical difference (P = .600) was found with non-OR athletes (SMD + = 0.15; 95% CI = −0.14, 0.45). However, subgroup analysis based on HRV parameter showed a moderate statistical increase in weekly averaged HRV in F-OR athletes (SMD + = 0.81; 95% CI = 0.35, 1.26), while isolated HRV values did not reach statistical significance (SMD + = −0.45; 95% CI = −0.96, 0.06).We observed a moderate and statistically significant increase in HRR indices among F-OR athletes (SMD + = 0.65; 95% CI = 0.44, 0.87), no changes for non-OR athletes (SMD + = 0.10; 95% CI = −0.15, 0.34), and statistically significant differences between F-OR and non-OR athletes (P < .001). Insufficient data prevented metaanalysis for post-exercise vagal-related HRV indices. Our findings show that when methodological factors are considered, HR-based indices are sensitive to increased PNS modulation in F-OR.

Fractal correlation properties of heart rate variability as a biomarker of endurance exercise fatigue in ultramarathon runners

“…Since exercise‐related fatigue is an inevitable consequence of a long duration endurance session, an easily available objective biomarker using a low‐cost consumer wearable device would be ideal. While resting heart rate (HR) variability (HRV) may provide information on functional overreaching, and post exercise HRV may indicate autonomic recovery status (Manresa‐Rocamora et al, 2021; Stanley et al, 2013), neither modality can answer the question of whether a specific exercise endeavor is leading to a fatigued state as the activity occurs.…”

Heart Rate Variability-Guided Training for Enhancing Cardiac-Vagal Modulation, Aerobic Fitness, and Endurance Performance: A Methodological Systematic Review with Meta-Analysis

“…Moreover, Schmitt, Willis, Fardel, Coulmy, Millet [ 18 ] compared single time-point HF values obtained pre-intervention with a 21-day averaged value obtained post-intervention. Isolated values inadequately represent autonomic status [ 12 , 54 , 55 , 56 ] and averaged values from such a lengthy follow-up are likely influenced by alterations in training (i.e., cessation, resumption, or variation not specified) and thus may not suitably reflect effects of the intervention [ 18 ]. The remaining studies used pre- and post-intervention RMSSD or SD 1 values averaged across 3–7 days in accordance with recent findings [ 12 , 54 , 55 , 56 , 57 , 58 ].…”

“…Isolated values inadequately represent autonomic status [ 12 , 54 , 55 , 56 ] and averaged values from such a lengthy follow-up are likely influenced by alterations in training (i.e., cessation, resumption, or variation not specified) and thus may not suitably reflect effects of the intervention [ 18 ]. The remaining studies used pre- and post-intervention RMSSD or SD 1 values averaged across 3–7 days in accordance with recent findings [ 12 , 54 , 55 , 56 , 57 , 58 ]. Finally, previous studies have reported potential bias of spectral indices due to non-stationarities [ 59 ].…”

“…Thus, it is possible that exercise prescription on the basis of daily HRV would vary depending on the recording position and potentially impact adaptations. One recent review paper identified standing measures as being more sensitive to changes in parasympathetic activity than other positions [ 56 ]. However, the optimal HRV assessment position for guiding daily training prescription and reflecting autonomic adaptation remains unclear.…”

Training History, Cardiac Autonomic Recovery from Submaximal Exercise and Associated Performance in Recreational Runners

“…There is little to no data on the short-term cANA response to successive submaximal short-lasting aerobic exercise bouts following exhaustive exercise on daily bases; nevertheless, this is a frequently used training regime in recreational athletes. A need for additional data on post-exercise vagal-related HRV indices is outlined by Manresa-Rocamora, to enable the tracking of cardiac parasympathetic activity (cPS) changes in relation to functional overreaching and overtraining [ 13 ].…”