Cinétiques des variables cardio-pulmonaires et métaboliques au cours d’épreuves exhaustives (temps limites) à 90, 100 et 105% de la vitesse maximale aérobie chez 16 coureurs élites.

Abstract

The topics of this study is : a) the measurement of the time to exhaustion at 90 (Tlim 90), 100 (Tlim 100) and 105 (Tlim 105) % of the maxi mal aerobic speed (MAS) defined as the minimal speed which elicits VO2max correlate these values with MAS, VO2max ; b) in order to better understand the reason of subjects abandonning, this work studies the changes in cardio-respiratory and metabolic variables versus time at each intensity at 90, 100 and 105 % of MAS. 16 elite male runners participated in this study. Their age, body mass, height, VO2 max and MAS were respectively : 27. 1 ± 4 years (mean = SD), 69.1 ± 5.5 kg, 178 ± 5 cm, 75 ± 5.3 ml.min-1. kg-1, 22.3 ± 1 km.h-1. All tests were performed on a treadmill. The VO2 max and MAS were measured in a preliminary test session using a progressive exercise protocol. The Tlim at 90 %, 100 % and 105 % of MAS were then measured and the subjects were randomly assigned on 3 sessions separated by one week each. Following a 15-min warm-up period at 60% MAS the running speed was rapidely increased (less than 20 s) up till 90%, 100% or 105% of MAS. Time limit mean values for 90, 100, 105 % of MAS respectively were 17.40 ± 4.30, 5.25 ± 1.31, 2.57 ± 0,43 min,s. Heart rate, blood lactate, VE and EQO2 increased significantly at the three intensities studied but VO2, VCO2 increased significantly near the test to exhaustion performed at 105 % of MAS (Tlim 105) only. Expiratory fraction of CO2 (FECO2) and Oxygen pulse (VO2/HR) significantly dropped near the end of the time limit at 90 % of MAS only. Arteriel oxyhaemoglobin saturation (% HBO2) dropped significantly near the end of Tlim 100 only, but was neither correlated with the time limit value at 100 % of MAS nor with the VO2 max value, time to exhaustion at 100 % of MAS (Tlim 100) is significantly correlated with Tlim 105 ip < 0.01, r = 0,759) but not with Tlim 90. Moreover, Tlim 100 and Tlim 105 values are respectively correlated negatively with VO2 max (r = -0,502 et -0,5 16, p < 0.05) and MAS (r = -0,691 et -0,603 p < 0.01). The significant increases and decreases of the physiological variables are different in relationship to running speed.