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Dupuy O.,University of Montreal | Dupuy O.,University of Poitiers | Bherer L.,Montreal Institute of Geriatrics | Bherer L.,University of Quebec at Montreal | And 4 more authors.
Applied Physiology, Nutrition and Metabolism | Year: 2013

The purpose of this study was to evaluate the effect of a 2-week overload period immediately followed by a 1-week taper period on the autonomic control of heart rate during the night or after exercise cessation. Eleven male endurance athletes increased their usual training volume by 100% for 2 weeks (overload) and decreased it by 50% for 1 week (taper). A maximal graded exercise test and a constant-speed test at 85% of peak treadmill speed, both followed by a 10-min passive recovery period, were performed at baseline and after each period. Heart rate variability was also measured during a 4-h period in the night or during estimated slow-wave sleep. All participants were considered to be overreached based on performance and physiological and psychological criteria. We found a decrease in cardiac parasympathetic control during slow-wave sleep (HFnu = 61.3% ± 11.7% vs 50.0% ± 10.1%, p < 0.05) but not during the 4-h period, as well as a faster heart rate recovery following the maximal graded exercise test (= 61.8 ± 14.5 s vs 54.7 ± 9.0 s, p < 0.05) but not after the constant-speed test, after the overload period. There was a return to baseline for both measures after the taper period. Other indices of cardiac autonomic control were not altered by the overload period. Care should be taken in selecting the most sensitive heart rate measures in the follow-up of athletes, because cardiac autonomic control is not affected uniformly by overload training.

Dupuy O.,University of Montreal | Dupuy O.,University of Poitiers | Mekary S.,University of Montreal | Mekary S.,Montreal Institute of Geriatrics | And 9 more authors.
Clinical Physiology and Functional Imaging | Year: 2012

Purpose: Postexercise HRR (heart rate recovery) and HRV (heart rate variability) are commonly used to asses non-invasive cardiac autonomic regulation and more particularly reactivation parasympathetic function. Unfortunately, the reliability of postexercise HRR and HRV remains poorly quantified and is still lacking. The aim of this study was to examine absolute and relative reliability of HRR and HRV indices used to assess postexercise cardiac parasympathetic reactivation. Methods: We studied 30 healthy men, who underwent 10-minute heart rate recording after cessation of maximal and submaximal intensity exercises. Each condition of testing was repeated twice within 5 ± 2 days after the first one. Standard indexes of HRR and HRV were computed from heart rate and RR intervals. Results: We found no significant bias between repeated measures. Relative reliability was assessed with the intraclass coefficient correlation (ICC) and absolute reliability with the standard error measurement (SEM) and coefficient of variation (CV). A large range for ICC was observed for both indexes of HRR and HRV (0·12 < ICC < 0·87 and 0·14 < ICC < 0·97, respectively). The same heterogeneity was observed for absolute reliability (5% < CV < 72% for HRR parameters and 24% < CV < 141% for HRV parameters). Conclusion: According to our results, {increment}60 (the absolute difference between heart rate immediately at the end of exercise and after 60 s) and HFnu (High Frequency expressed in normalized unit; that is, in a percentage of LF+HF) represent the most reliable parameters. In conclusion, we found that the measures used to asses cardiac parasympathetic reactivation were characterized by large random variations and their reliability remains moderate. © 2012 Scandinavian Society of Clinical Physiology and Nuclear Medicine.

Dupuy O.,University of Poitiers | Dupuy O.,University of Montreal | Lussier M.,Montreal Institute of Geriatrics | Lussier M.,University of Quebec at Montreal | And 8 more authors.
Scandinavian Journal of Medicine and Science in Sports | Year: 2014

The purpose of this study was to characterize the effect of a 2-week overload period immediately followed by a 1-week taper period on different cognitive processes including executive and nonexecutive functions, and related heart rate variability. Eleven male endurance athletes increased their usual training volume by 100% for 2 weeks, and decreased it by 50% for 1 week. A maximal graded test, a constant speed test at 85% of peak treadmill speed, and a Stroop task with the measurement of heart rate variability were performed at each period. All participants were considered as overreached. We found a moderate increase in the overall reaction time to the three conditions of the Stroop task after the overload period (816±83 vs 892±117ms, P=0.03) followed by a return to baseline after the taper period (820±119ms, P=0.013). We found no association between cognitive performance and cardiac parasympathetic control at baseline, and no association between changes in these measures. Our findings clearly underscore the relevance of cognitive performance in the monitoring of overreaching in endurance athletes. However, contrary to our hypothesis, we did not find any relationship between executive performance and cardiac parasympathetic control. © 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

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