Proceedings of The Physiological Society

University of Oxford (2011) Proc Physiol Soc 23, PC74

Poster Communications

Physical training reduces time-domain ventilatory variability during exercise in healthy individuals

A. Nobrega1, R. Castro1, S. Allan1

1. Fluminense Federal University, Niteroi, RJ, Brazil.

Introduction: Ventilatory variability during exercise exhibits prognostic information in heart failure patients (1,2) and inversely correlates to left ventricle ejection fraction in heart failure patients (3). We have previously proposed the application of time-domain variability techniques to quantify ventilatory oscillations during exercise. Few studies have investigated strategies to reverse exercise periodic breathing. A recently published case report have shown reversion of exercise periodic breathing after 4 months of cardiac rehabilitation in a patient with heart failure (4). In a cross- sectional study, sedentary men exhibited higher ventilatory variability during maximal exercise test when compared to athletes (5). However, it is unknown whether this result is an effect of exercise training itself or a result from a selection bias. Objective: To evaluate the effects of physical training on time-domain ventilatory variability during dynamic exercise in healthy subjects. Methods: Randomized controlled trial where time-domain ventilatory variability during exercise was evaluated in 24 healthy individuals before and after 12 weeks of exercise training (Exercise group, n=12) or no intervention (control group, n=12). Standard deviation (SD) and root mean square successive difference (RMSSD) of VE, RR and Vt during exercise test were calculated for each patient, and normalized by the number of respiratory cycles (SD/n and RMSSD/n, respectively) (5). Results: Before training, the groups were comparable. After 12 weeks, volunteers in the exercise group presented higher peak oxygen consumption (37.12±2.51 vs. 25.9±1.46, P<0.001) and lower body mass index (23.39±0.70 vs. 26.32±0.70, P=0.008) than individuals in control group. In addition, time-domain variability of respiratory rate during exercise was higher in the control group when compared to volunteers in the exercise group after intervention (table 1). Conclusion: Exercise training reduced time-domain ventilatory variability of healthy individuals during a maximal exercise test. The impact of this adaptation remains to be evaluated.

Where applicable, experiments conform with Society ethical requirements