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This Article Full Text Full Text (PDF) All Versions of this Article: 296/5/H1651    most recent 00881.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Blain, G. Articles by Bermon, S. Search for Related Content PubMed PubMed Citation Articles by Blain, G. Articles by Bermon, S.

Time-frequency analysis of heart rate variability reveals cardiolocomotor coupling during dynamic cycling exercise in humans

¹Laboratory of Physiological Adaptations, Motor Performance and Health, Faculty of Sports Sciences (UFR STAPS), University of Nice-Sophia Antipolis, Nice; and ²Laboratory I3S, University of Nice-Sophia Antipolis, Sophia Antipolis, France; and ³Monaco Institute of Sports Medicine and Surgery, Monaco, Principality of Monaco

Submitted 9 August 2008 ; accepted in final form 23 February 2009

To test the hypothesis that cycling exercise modulates heart rate variability (HRV), we applied a short-time Fourier transform on the electrocardiogram of subjects performing a maximal graded cycling test. A pedaling frequency component (PFC) in HRV was continuously observed over the time course of the exercise test and extracted from R-R interval series obtained from 15 healthy subjects with a heterogeneous physical fitness, exercising at three different pedaling frequency (n = 5): 70, 80, and 90 rpm. From 30 to 50% of the maximal power output (P_max), in the 90 rpm group, spectral aliasing caused PFC to overlap with the respiratory sinus arrhythmia (RSA) band, significantly overestimating the PFC amplitude (A_PFC). In the meantime, A_PFC did not increase significantly from its minimal values in the 70 rpm (1.26 ms) and 80 rpm (1.20 ms) groups. Then, from 60 to 100% maximal power output (P_max), workload increase caused a significant 2.8-, 3.3-, and 3.4-fold increase in A_PFC in the 70, 80, and 90 rpm groups, respectively, with no significant difference between groups. At peak exercise, A_PFC accounted for 43, 39, and 49% of the total HRV in the 70, 80, and 90 rpm groups, respectively. Our findings indicate that cycling continuously modulates the cardiac chronotropic response to exercise, inducing a new component in HRV, and that workload increase during intense exercise further accentuates this cardiolocomotor coupling. Moreover, because PFC and RSA overlapped at low workloads, methodological care should be taken in future studies aiming to quantify RSA as an index of parasympathetic activity.

respiratory sinus arrhythmia; exercise; locomotion; pedaling frequency component