Validity of Two High-Incline VO2max Protocols for College-Aged Population

Purpose: The aim of the study is to validate two high-incline Graded Exercise Tests (GXT) that could be used as alternatives to the Bruce protocol to obtain VO2max values for college-aged individuals who may not be accustomed to running on a treadmill. Methods: Subjects (n = 42, male = 25, female = 17, age = 23.2 ± 2.6 years) completed the Bruce protocol as well as two high-incline GXTs (5-5, 10-5) in a randomized order. Both high incline VO2max tests were performed at a constant speed of 3.6 mph and increased in incline of 5% every 3-minutes until volitional exhaustion. The 5-5 began with a 5% grade, while the 10-5 began with a 10% grade. Outcome measurements of VO2max were compared using a 1 x 3 repeated measures ANOVA. Pearson Correlation and Bland-Altman plots were used to analyze relationships between the two high-incline tests and the Bruce protocol individually. Results: No differences in VO2max was found between tests (Bruce = 45.99 ± 7.57 ml∙kg-1∙min-1, 5-5 = 44.97 ± 7.71 ml∙kg-1∙min-1, 10-5 = 43.99 ± 8.01 ml∙kg-1∙min-1, p > 0.05). VO2max of the Bruce protocol was strongly related to both 5-5 (R = 0.95) and 10-5 (R = 0.91) tests. Bland-Altman plots between the 5-5 test and the Bruce protocol revealed 93% of data falls within ± 4.5 ml∙kg-1∙min-1 of the arbitrary accepted range. For comparison between 10-5 and Bruce, variability increased as only 79% of the data fell within the same arbitrary range. Conclusion: Results suggest that the 5-5 test is a valid alternative to the Bruce protocol. Additionally, the current study demonstrates that a non-running GXT is effective in determining VO2max in a relatively healthy, college-aged population.