Change in Performance in Response to Training Load Adjustment Based on Autonomic Activity

The primary aim of this study was to assess performance (Perf) changes in response to a new training strategy. Specifically, based on spectral analysis of heart rate variability (SA HRV) to determine autonomic nervous system (ANS) activity, training doses were adjusted to maintain vagal activity at a high and relatively stable level during training preparation. Trained athletes (5 male and 5 female) aged 23.2 +/- 4.2 years voluntarily participated in the study. ANS activity was assessed during an orthoclinostatic test, and was represented by calculating HRV variables and a total score index. Over 17 weeks, improvement (1.4-8.5%) and deterioration (0.1-8.8%) in Perf were detected in 7 and 3 athletes, respectively. A relationship (rs = 0.684; P < 0.05) between the change in Perf (Delta Perf) and supine PHF during season was found. Supine HRV indices (P-HF, P-T, and MSSD) for the last 3 weeks of the HRV-adjusting period correlated (rs = 0.636; 0.648; 0.648, P < 0.05) with Delta Perf. Based on the results, a high and relative stable vagal activity during preparation may indicate a readiness to train or appropriate recovery that positively affects Perf. In conclusion, daily quantification of ANS activity by SA HRV seems to be a promising tool for the enhancement of Perf.