Attenuation of the increase of heart rate and oxygen consumption during progressive exercise in professional rugby players.

Abstract

The response of oxygen uptake (VO<inf>2</inf>) and heart rate (HR) to continuous progressive large muscle mass exercise is not always linear. This study aimed to compare the patterns of the Speed/VO<inf>2</inf> (S/VO<inf>2</inf>) and speed/HR (S/HR) relationships during an incremental treadmill-running test in professional rugby players. Fourteen professional rugby athletes performed a maximal incremental treadmill-running test, following the Conconi test protocol. Speed, heart rate, and gas exchange parameters were recorded. The slope of the S/VO<inf>2</inf> and S/HR relationships were mathematically determined. The S/VO<inf>2</inf> and S/HR relationships were linear up to a submaximal speed and curvilinear thereafter. The speed of locomotion at which the slope of the S/VO<inf>2</inf> and S/HR relationships start to attenuate (VO<inf>2att</inf> and HR<inf>att</inf>) were coincident (12.3±1.0 and 12.4±0.9 km/h), strongly correlated and in good agreement. VO<inf>2</inf> values at VO<inf>2att</inf> (44.9±8.7 mL/kg/min) were significantly correlated with VO<inf>2</inf> values at the ventilatory threshold (43.3±6.0 mL/kg/min) (R2=0.83, P=0.001) and in good agreement. The running speed/VO<inf>2</inf> ratio (ΔS/ΔVO<inf>2</inf>) up to VO<inf>2att</inf> was significantly lower than that beyond VO<inf>2att</inf> (2.98±1.1 vs. 5.16±2.31); P<0,001). The speed/oxygen uptake and S/HR relationships during progressive exercise start to attenuate at a coincident exercise intensity, and at oxygen uptake values strongly correlated with the ventilatory threshold. These findings further support the usefulness of the attenuation of the S/HR relationship as a practical tool for exercise testing and training purposes in professional rugby players.