Cardiometabolic and Perceptual Responses to Maximal Exercise: Comparing Graded Walking to Ungraded Running

Abstract

Graded exercise testing for determination of aerobic capacity can be conducted in numerous ways with treadmill testing representing the primary modality. Achieving maximal effort on a treadmill can be accomplished by increasing speed and/or grade. Research to date comparing graded walking maximal tests to ungraded running tests is limited. PURPOSE: Compare the cardiometabolic responses to two treadmill-based maximal tests, namely graded walking and ungraded running. METHODS: 20 healthy participants (11 females, 9 males; mean BMI = 25; mean age = 24) completed two counterbalanced cardiometabolic exercise tests. The WALK trial started with a brisk and comfortable walking speed and increased grade by 2% every minute until exhaustion and the RUN trial started with a comfortable walking speed and increased by 0.5 mph every minute until exhaustion. Expired gases, HR, overall RPE (RPE-O), and legs only RPE (RPE-L) were assessed during the test. RESULTS: Data was analyzed using dependent t-tests. The RUN and WALK trials produced similar maximal values for RPE-O, RPE-L, and VO2 (all p-values > 0.05; all ES values < 0.2), though HR was significantly higher in the RUN trial (p < 0.05; ES = 0.4), and RER was significantly higher in the WALK trial (p < 0.01; ES = 0.8). CONCLUSIONS: Findings indicate that both walk-based and run-based exercise tests produce similar perceptual responses that indicate maximal effort, and similar VO2max values despite very different approaches to creating intense work. The observed difference in HR suggests that a run-based maximal exercise test produces a greater cardiovascular response, while the higher RER value within the walk-based maximal exercise test suggests greater metabolic acidosis. Results support treadmill exercise testing as a flexible multiple assessment modality.