Respiratory responses and rating of perceived exertion of severely obese adolescents during continuous and intermittent graded walking protocols: Application to cardiorespiratory field tests

J Sports Sci. 2020 May;38(9):1009-1017. doi: 10.1080/02640414.2020.1738701. Epub 2020 Mar 11.


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.

Keywords: 20m shuttle run test; Obese; adolescents; cardiorespiratory test; intermittent.

MeSH terms

  • Adolescent
  • Cardiorespiratory Fitness / physiology*
  • Energy Metabolism / physiology
  • Exercise Test
  • Female
  • Humans
  • Male
  • Oxygen Consumption / physiology
  • Pediatric Obesity / physiopathology*
  • Pediatric Obesity / psychology
  • Perception / physiology*
  • Physical Exertion / physiology*
  • Respiration*
  • Walking / physiology*