To assess whether entrainment of breathing (E) during exercise: 1) differed according to the test protocol in well-trained triathletes, and 2) improved ventilatory efficiency during exercise.
Eight triathletes performed three incremental tests until exhaustion: while cycling (CE), while running at increasing grade and constant speed (↑ GRADE) and while running at increasing speed and constant grade (↑ SPEED), respectively. E was evaluated as the percentage of breaths occurring at respiratory rates (F) corresponding to integer ratios of the exercise cycle rate. To assess whether E improved ventilatory efficiency,Δ˙VE/˙VO2 between nonentrained and entrained breaths was measured at each load.
Mean E was higher in CE (57.2 ± 21.9%) than in ↑ GRADE (46.9± 18.7%) and ↑ SPEED (41.4 ± 17.2%). E decreased at high loads in Ce and ↑ SPEED but not in ↑ GRADE. In the group of subjects, E correlated with the degree of fitness (evaluated as˙VO2Tvent/˙VO2peak%) only during ↑ GRADE. By multiple regression analysis on all data, minute ventilation correlated with CO2 production but not with the exercise cycle rate; however, either F or tidal volume correlated significantly with both these variables.˙VE/˙VO2 was lower in entrained than nonentrained breaths at each load in CE and ↑ GRADE experiments, but the difference was small.
In spite of some differences among protocols, triathletes showed significant E during incremental exercise tests. Spontaneous E appeared to slightly improve ventilatory efficiency during CE and ↑ GRADE protocols.
Istituto di Scienze e Tecnologia dello Sport e dell'Attività Fisica and Istituto di Fisiopatologia Respiratoria, Consiglio Nazionale delle Ricerche, Palermo, ITALY
Submitted for publication January 1997.
Accepted for publication July 1997.
This work has been presented in abstract form at the 1996 Intersociety Conference “The Integrative Biology of Exercise,” October 16-19, 1996, Vancouver, British Columbia, Canada.
Address for correspondence: Maria R. Bonsignore, ISTSAF-CNR, Via Trabucco 180, 90146 Palermo, Italy. E-mail: romano@IFRPA.IFR.PA.CNR.IT.