LAUSR

ABSTRACT During 20 m shuttle tests, obese adolescents may have difficulty achieving maximum cardiorespiratory performance due to the presence of braking-relaunch phases (BRP). Nineteen obese adolescents aged 15.2 ± 1.5 years (body mass index [BMI] = 39.7 ± 5.9 kg.m−2) performed three graded walking exercises on a 50 m track at speeds between 3 and 6 km/h: a continuous-straight-line protocol (C), a continuous protocol that required turning back every 30 sec (C-BRP) and an intermittent protocol that consisted of successively walking then resting for 15 sec (15–15). Oxygen uptake (VO2), aerobic cost of walking (Cw), ventilation (VE) and rating of perceived exertion (RPE) were measured at each stage during the protocols. During C-BRP, the responses were not significantly higher compared with C (p > 0.30). During 15–15, the VO2, Cw and VE were ~ 15 to 25% lower than during C beginning at 4 km/h (p < 0.05). In obese adolescents, the respiratory impact of sudden directional changes during the 20 m shuttle-type test appeared to be minor at walking speeds. During the 15–15 test, the intensity increases more progressively, and this design may encourage obese adolescents to walk further than during a continuous test.