MAXIMAL OXYGEN CONSUMPTION IS SIMILAR WITH DECREMENTAL AND TRADITIONAL INCREMENTAL PROTOCOLS IN RUNNERS AND TRIATHLETES

For more than 90 years, researchers have utilized incremental protocols to measure maximal oxygen consumption (VO2max). However, more recently there has been research to suggest that a decremental protocol may elicit a higher VO2max than an incremental protocol. PURPOSE: To determine whether a decremental protocol could produce higher VO2max values than an incremental protocol, and to understand the potential mechanism underlying this phenomenon. METHODS: 20 runners/triathletes (mean±SD: age 28.0±6.9 y) were randomized to one of two groups: incremental (n=10) or decremental (n=10). All participants completed an initial incremental VO2max test, followed by a verification phase. Participants in the incremental group then completed two further incremental tests on a treadmill beginning at 5.6 mph (4.4 mph for women) at a 5% grade. Participants in the decremental group completed a second VO2max using the decremental protocol, which was based on the results of their initial incremental test. The decremental group also completed a third VO2max test using the incremental protocol. All testing was separated by at least 72 h. During each test VO2, VCO2, ventilation, and heart rate were measured using a metabolic cart system and cardiac variables were estimated with thoracic bioimpedance. A 2x3 repeated measures ANOVA was conducted with an alpha level set at 0.05. RESULTS: There were no significant main effects for group or interaction over time (p\u3e0.05). Average VO2max over three trials was similar between the incremental (56.4±0.9 ml/kg/min) and decremental (60.8±0.9 ml/kg/min) groups (p\u3e0.05). The average difference in VO2max across the 3 trials was 0.18 ml/kg/min for incremental and 0.24 ml/kg/min for decremental groups (p\u3e0.05). Furthermore, there were no significant differences in average cardiac output (Q) or stroke volume (SV) over three trials between the incremental (Q:23.9±0.6 L/min; SV:126.9±3.2 ml/beat) and decremental groups (Q:20.3±0.5 L/min; SV:108.1±2.9 ml/beat). CONSLUSIONS: The findings of this study suggest that a decremental protocol does not elicit higher VO2max values than an incremental protocol. However, there is evidence to suggest that a decremental protocol can be used as an alternative protocol to measure VO2max in runners and triathletes