A-27 Free Communication/Poster - Clinical Exercise Testing: MAY 27, 2009 7:30 AM - 12:30 PM ROOM: Hall 4F
Maximal aerobic capacity (VO2max) testing is used in exercise interventions to establish baseline rates of cardiovascular function and as an objective measure of intervention effects. However, participants in exercise interventions are likely sedentary, and unaccustomed to pushing themselves to their maximum capacity, potentially leading to inaccurate assessments of VO2max.
PURPOSE: To determine rates and predictors of meeting a valid VO2max in sedentary individuals.
METHODS: 285 sedentary men and women participating in the Colorado STRIDE exercise intervention RCT completed a VO2max test. We tested three of the four criteria for a valid VO2max test: 1. Respiratory exchange ratio (RER) ≥ 1.1; 2. Achievement of age predicted maximum heart rate (HR); 3. Rating of perceived exertion (RPE) ≥ 18. BMI, age, self-reported exercise frequency over the previous three months (EF3), and total minutes of at least moderate physical activity over the past week (MINWK) were examined as predictors of a valid VO2max.
RESULTS: Preliminary results indicated that 50.2% of participants achieved all three criteria and 13.0% achieved one or none of the criteria tested. Age (OR = -1.06, p < 0.01), EF3 (OR = -1.02, p < 0.01), and MINWK (OR = -1.00, p = 0.03) significantly predicted whether or not participants reached an RER ≥ 1.1. BMI (OR = 0.91, p = 0.03) predicted whether or not a participant reached an RPE ≥18. There were no significant predictors of whether or not a participant came within 10bpm of age-predicted maximum HR. BMI (Adj. OR = -0.92, p = 0.05), EF3 (Adj. OR = -0.34, p < 0.01) and age (Adj. OR = 1.05, p = 0.07) predicted whether or not a participant met all three criteria.
CONCLUSIONS: Most participants provided a valid VO2max test. Older, less active individuals were more likely to achieve the RER threshold and to meet all three criteria. Individuals with higher BMI were more likely to achieve the RPE threshold but less likely to meet all three criteria. VO2max testing may be particularly difficult for individuals with higher BMI, even for those that are more active. RPE may not be a good criterion for achieving a valid VO2max in these individuals because subjectively they are experiencing greater exertion while, based on more objective physiological measures, they are not working as hard as those who have a lower BMI.