Physiological and Perceptual Responses to Step-Wise and Ramp Graded Exercise Tests in Children

Abstract

Step-wise graded exercise tests are common protocols to measure aerobic fitness in children but have limitations due to the nature of the increments. Modifying these tests to a ramp protocol could overcome some of these limitations. PURPOSE: To examine physiological and perceptual responses to step-wise and ramped graded exercise tests in children (n = 8; age = 13.3 ± 2.2 yrs.). METHODS: The standardized James protocol (STEP) and a modified-ramp James protocol (RAMP) were performed on a cycle ergometer on separate days. Protocol order was counterbalanced. STEP commenced with three 3-min stages, followed by 1-min stages. Work rate increases were based on body surface area. For RAMP, work rate was ramped to match the 3-min and 1-min stages of STEP. Work rate was increased until volitional exhaustion for both tests. Oxygen consumption (VO2), heart rate (HR), respiratory exchange ratio (RER) and OMNI ratings of perceived exertion for chest (RPE-chest), legs (RPE-legs) and overall (RPE-overall) were recorded at the end of each 3-minute stage and peak exercise. Physiological and perceptual responses between tests were compared using two-way repeated-measure ANOVAs and test time (TT) and peak power (PP) were compared using repeated measure t-tests. Significance was established at p<0.05. RESULTS: The physiological and RPE responses were similar between tests at the end of each 3-min submaximal stage (p>0.05). At peak exercise, absolute and relative VO2 for STEP were 2.17 ± 0.67 L∙min-1 and 42.5± 5.9 ml∙kg-1 ∙min-1. For RAMP, absolute and relative VO2peak were 2.33± 0.89 L∙min-1 and 45.3 ± 8.9 ml∙kg-1 ∙min-1. The differences were not significant. There were no differences between STEP and RAMP for peak HR (196.3 ± 9.8 bpm vs. 196.1 ± 9.7 bpm) and peak RER (1.24 ± 0.11 vs. 1.21 ± 0.06). At peak exercise, RPE-chest, RPE-leg and RPE-overall were similar between STEP (4.8 ± 4.0, 8.4 ± 2.1 and 7.6 ± 3.0, respectively) and RAMP (5.6 ± 3.4, 8.5± 2.3 and 8.0± 1.8, respectively) (p>0.05). TT and PP for STEP were 11.3± 2.5 min and 196.8 ± 70.7 W and 12.4 ± 2.4 min and 210.3 ± 65.5 W for RAMP (p=0.11 and p=0.12, respectively) CONCLUSION: Although limitations in step-wise protocols exist, submaximal and peak physiological and perceptual responses were similar to a ramp protocol. Both protocols may be appropriate in children to measure aerobic fitness.