Introduction During cycling and running, the locomotor rhythm can modulate the heart rate (HR), although the characteristics of cardiolocomotor coupling are different in the two exercise modes (Nomura et al., 2003). Furthermore, it was recently demonstrated that in cycling the interactions between the locomotor and heart rhythms result in a new heart rate variability (HRV) spectral component corresponding to pedalling frequency (Blain et al., 2009). This study aimed to analyse the spectrum of the RR signal collected during an incremental running test, in order to individuate the frequency and magnitude of spectral components originating from cardiolocomotor interactions. Methods On a grass field, nineteen male soccer players performed an exhaustive running test, with speed starting at 8.5 km/h and increasing by 0.5 km/h every minute. During the test, self-selected stride rate (SR) and RR periods were measured. A Short-time Fourier transform was applied to the RR series to estimate the power spectra. Results In all the subjects, the analysis of time-varying spectra allowed to detect two spectral frequency components related to SR. The first component (F1) was at a frequency of one half the SR (1.2 to 1.6 Hz), whereas the frequency of the second component (F2) equalled the absolute value of the SR-HR difference (0 to 0.8 Hz). At 80, 90, and 100% of maximum HR, the magnitude of F1 was 19.2 ± 10.2, 17.8 ± 9.3, and 15.0. ± 8.2 % of total high-frequency power (HF, >0.15 Hz). At the same intensities, F2 represented 19.6 ± 13.4, 16.6 ± 9.5, and 13.2 ± 7.4 % of HF. Discussion The presence of F1 confirmed what observed in cycling (Blain et al., 2009), i.e. a spectral component corresponding to the main locomotor rhythm that represents a significant portion of HF power and appears even when the cardiac and locomotor rates are not synchronous. The mechanism underlying F1 is probably the modulation of venous return by limb muscles contraction. The main finding of this study is however the appearance of the F2 component. F2 could have links with the relationship between the instantaneous RR variation and the phase of the cardiac cycle in which the vastus lateralis contraction occurs (Nomura et al., 2006). Finally, the presence of F2 in the same frequency ranges of the low frequency and the respiratory components could lead to overestimate the spectral power relative to those components, requiring caution when interpreting the frequency analysis of HRV collected during running. References Blain G, Meste O, Blain A, Bermon S (2009). Am J Physiol Heart Circ Physiol, 296(5), H1651-H1659. Nomura K, Takei Y, Yanagida Y (2003). Eur J Appl Physiol, 89,221-229. Nomura K, Takei Y, Yoshida M, Yanagida Y (2006). Eur J Appl Physiol, 97, 240-247.

Effects of cardiolocomotor interactions on the spectrum of heart rate variability during running

DI MICHELE, ROCCO;MERNI, FRANCO
2011

Abstract

Introduction During cycling and running, the locomotor rhythm can modulate the heart rate (HR), although the characteristics of cardiolocomotor coupling are different in the two exercise modes (Nomura et al., 2003). Furthermore, it was recently demonstrated that in cycling the interactions between the locomotor and heart rhythms result in a new heart rate variability (HRV) spectral component corresponding to pedalling frequency (Blain et al., 2009). This study aimed to analyse the spectrum of the RR signal collected during an incremental running test, in order to individuate the frequency and magnitude of spectral components originating from cardiolocomotor interactions. Methods On a grass field, nineteen male soccer players performed an exhaustive running test, with speed starting at 8.5 km/h and increasing by 0.5 km/h every minute. During the test, self-selected stride rate (SR) and RR periods were measured. A Short-time Fourier transform was applied to the RR series to estimate the power spectra. Results In all the subjects, the analysis of time-varying spectra allowed to detect two spectral frequency components related to SR. The first component (F1) was at a frequency of one half the SR (1.2 to 1.6 Hz), whereas the frequency of the second component (F2) equalled the absolute value of the SR-HR difference (0 to 0.8 Hz). At 80, 90, and 100% of maximum HR, the magnitude of F1 was 19.2 ± 10.2, 17.8 ± 9.3, and 15.0. ± 8.2 % of total high-frequency power (HF, >0.15 Hz). At the same intensities, F2 represented 19.6 ± 13.4, 16.6 ± 9.5, and 13.2 ± 7.4 % of HF. Discussion The presence of F1 confirmed what observed in cycling (Blain et al., 2009), i.e. a spectral component corresponding to the main locomotor rhythm that represents a significant portion of HF power and appears even when the cardiac and locomotor rates are not synchronous. The mechanism underlying F1 is probably the modulation of venous return by limb muscles contraction. The main finding of this study is however the appearance of the F2 component. F2 could have links with the relationship between the instantaneous RR variation and the phase of the cardiac cycle in which the vastus lateralis contraction occurs (Nomura et al., 2006). Finally, the presence of F2 in the same frequency ranges of the low frequency and the respiratory components could lead to overestimate the spectral power relative to those components, requiring caution when interpreting the frequency analysis of HRV collected during running. References Blain G, Meste O, Blain A, Bermon S (2009). Am J Physiol Heart Circ Physiol, 296(5), H1651-H1659. Nomura K, Takei Y, Yanagida Y (2003). Eur J Appl Physiol, 89,221-229. Nomura K, Takei Y, Yoshida M, Yanagida Y (2006). Eur J Appl Physiol, 97, 240-247.
Book of Abstracts of the 16th Annual Congress of the European College of Sport Science, 6-9 July 2011 Liverpool - United Kingdom
526
526
Di Michele R.; Merni F.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/103300
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