The effect of functional overreaching on parameters of autonomic heart rate regulation
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Correlations between fatigue-induced changes in performance and maximal rate of HR increase (rHRI) may be affected by differing assessment workloads. This study evaluated the effect of assessing rHRI at different workloads on performance tracking, and compared this with HR variability (HRV) and HR recovery (HRR).
Performance [5-min cycling time trial (5TT)], rHRI (at multiple workloads), HRV and HRR were assessed in 12 male cyclists following 1 week of light training (LT), 2 weeks of heavy training (HT) and a 10-day taper (T).
5TT very likely decreased after HT (effect size ± 90% confidence interval = −0.75 ± 0.41), and almost certainly increased after T (1.15 ± 0.48). rHRI at 200 W likely increased at HT (0.70 ± 0.60), and then likely decreased at T (−0.50 ± 0.70). rHRI at 120 and 160 W was unchanged. Pre-exercise HR during rHRI assessments at 120 W and 160 W likely decreased after HT (≤−0.39 ± 0.14), and correlations between these changes and rHRI were large to very large (r = −0.67 ± 0.31 and r = −0.78 ± 0.23). When controlling for pre-exercise HR, rHRI at 120 W very likely slowed after HT (−0.72 ± 0.44), and was moderately correlated with 5TT (r = 0.35 ± 0.32). RMSSD likely increased at HT (0.75 ± 0.49) and likely decreased at T (−0.49 ± 0.49). HRR following 5TT likely increased at HT (0.84 ± 0.31) and then likely decreased at T (−0.81 ± 0.35).
When controlling for pre-exercise HR, rHRI assessment at 120 W most sensitively tracked performance. Increased RMSSD following HT indicated heightened parasympathetic modulation in fatigued athletes. HRR was only sensitive to changes in training status when assessed after maximal exercise, which may limit its practical applicability.
KeywordsHeart rate Overreaching Athletic performance Autonomic nervous system
Autonomic nervous system
Daily analysis of life demands for athletes
Heart rate at the end of exercise
Heart rate recovery
Heart rate variability
- Ln RMSSD
Natural logarithm of the root-mean-square difference of successive normal R-R intervals
Maximal rate of heart rate increase
- rHRI120 W
Maximal rate of heart rate increase assessed at 120 watts
- rHRI160 W
Maximal rate of heart rate increase assessed at 160 watts
- rHRI200 W
Maximal rate of heart rate increase assessed at 200 watts
- rHRI120–200 W
Maximal Rate of Heart Rate Increase assessed during transition from 120 W to 200 watts
Five-minute time trial
Sixty-minute time trial
This study was supported by a grant from the Australian Research Council (LP140101013) in partnership with Polar Electro Oy and the South Australian Sports Institute. Researcher Bellenger was supported by an Australian Postgraduate Award from the Australian Commonwealth Government and research scholarship from the South Australian Sports Institute.
Compliance with ethical standards
Conflict of interest
The University of South Australia has applied for a patent on the rHRI technology described in this manuscript, and researchers Davison and Buckley are employees of the University. Researcher Karavirta is an employee of Polar Electro Oy.
Was granted by the University of South Australia’s Human Research Ethics Committee, and volunteers provided written informed consent prior to participating. All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
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