| Abstrakt: |
Purpose: Assessment of heart rate variability (HRV) during exercise is an emerging area of study. Measurements of HRV are characterized by domain (time, frequency, and nonlinear) or time scale (short or long-term). The purpose of this study was to compare methods of HRV analysis during submaximal running before and after 18 weeks of marathon training. Methods: Pre and post-training, 42 recreational runners (21.1 ± 1.5 years, 28 f) completed a 2-mile (3218 m) time trial (2MI) and a submaximal run (SUBMAX) at 75% of 2MI speed. Changes in HRV during SUBMAX and physiological measures were assessed with paired samples t tests. Correlations between the changes of selected variables were assessed with Spearman's rho. Results: Long-term measures of HRV did not change with training, while several short-term measures changed: Poincaré plot SD1 (PPSD1) (2.9 ± 0.9, 3.5 ± 1.5; p = 0.049), PPSD1.PPSD2−1 (0.23 ± 0.11, 0.29 ± 0.17; p = 0.047) and Detrended Fluctuation Analysis α1 (0.95 ± 0.25, 0.82 ± 0.28; p = 0.006). Both 2MI (15.6 ± 2.0 min, 14.2 ± 1.7 min; p ≤ 0.001) and VO2max (50.6 ± 7.6, 52.7 ± 7.3; p = 0.049) improved with training. Change in sample entropy (SampEn) was correlated with change in 2MI (rho = − 0.379, p = 0.016), suggesting an association between this measure of HRV and endurance performance. Conclusions: Measures of short-term HRV change with marathon training and may reflect adaptation independent of change in aerobic capacity. [ABSTRACT FROM AUTHOR] |
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