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Assessment of ventilatory thresholds during graded and maximal exercise test using time varying analysis of respiratory sinus arrhythmia
  1. G Blain1,
  2. O Meste2,
  3. T Bouchard3,
  4. S Bermon1
  1. 1Département Ergonomie Sportive et Performances, Universite de Toulon-Var, Nice, France
  2. 2Laboratoire I3S, Universite de Nice Sophia-Antipolis, Nice, France
  3. 3Universite de Nice Sophia-Antipolis, Nice, France
  1. Correspondence to:
 Gregory Blain
 Universite de Toulon-Var, Département Ergonomie Sportive et Performances, Avenue Valombrose, NICE cedex 2 06107, France;


Objective: To test whether ventilatory thresholds, measured during an exercise test, could be assessed using time varying analysis of respiratory sinus arrhythmia frequency (fRSA).

Methods: Fourteen sedentary subjects and 12 endurance athletes performed a graded and maximal exercise test on a cycle ergometer: initial load 75 W (sedentary subjects) and 150 W (athletes), increments 37.5 W/2 min. fRSA was extracted from heart period series using an evolutive model. First (TV1) and second (TV2) ventilatory thresholds were determined from the time course curves of ventilation and ventilatory equivalents for O2 and CO2.

Results:fRSA was accurately extracted from all recordings and positively correlated to respiratory frequency (r = 0.96 (0.03), p<0.01). In 21 of the 26 subjects, two successive non-linear increases were determined in fRSA, defining the first (TRSA1) and second (TRSA2) fRSA thresholds. When expressed as a function of power, TRSA1 and TRSA2 were not significantly different from and closely linked to TV1 (r = 0.99, p<0.001) and TV2 (r = 0.99, p<0.001), respectively. In the five remaining subjects, only one non-linear increase was observed close to TV2. Significant differences (p<0.04) were found between athlete and sedentary groups when TRSA1 and TRSA2 were expressed in terms of absolute and relative power and percentage of maximal aerobic power. In the sedentary group, TRSA1 and TRSA2 were 150.3 (18.7) W and 198.3 (28.8) W, respectively, whereas in the athlete group TRSA1 and TRSA2 were 247.3 (32.8) W and 316.0 (28.8) W, respectively.

Conclusions: Dynamic analysis of fRSA provides a useful tool for identifying ventilatory thresholds during graded and maximal exercise test in sedentary subjects and athletes.

  • AT, anaerobic threshold
  • HP, heart period
  • HPV, heart period variability
  • RSA, respiratory sinus arrhythmia
  • anaerobic threshold
  • athletes
  • endurance training
  • heart period variability
  • time varying model

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  • Competing interests: none declared