B16j Thematic Poster Session Exercise Evaluation - Clinical
Older adults (65+) account for approximately 1.25 million stress tests per year. Treadmill ergometry is the modality of choice in most settings, and VO2 max is typically estimated using prediction equations that are mechanically derived, i.e. treadmill grade, speed, time.
Our aims were;
- (1) to explore the accuracy of treadmill prediction equations in a sample of older, de-conditioned men and women; and
- (2) to examine the mechanical and physiological predictors of VO2 max, in order to further understand which variables predict cardiovascular fitness in the elderly.
177 community dwelling, older men (72.6 ± 4.8 years) and women (71.0 ± 5.1 years) previously screened for participation in a randomized clinical trial were retrospectively examined. VO2 max was measured via open circuit spirometry during a symptom-limited maximal exercise tolerance test, using an individualized ramping protocol. Measured VO2 max values were compared to Myers' (ramp) and the ACSM walking equation (ACSM). Regression analysis was employed to determine significant predictors of measured VO2 max.
In men, the ACSM equation overestimated VO2 max, whereas the ramp equation was not significantly different (p = 0.0990). In women, the ACSM and the ramp equation overestimated measured VO2 max. In men and women, the ACSM and ramp equations accounted for approximately 50% of the variance in measured VO2 max (see Table). (Table: Mean ± SD; *p < 0.0001 measured v. predicted VO2 max) Inregressionalyses, significantpredictorsofVO 2 max were sex (p < 0.0001), BMI (p < 0.0001), treadmill grade (p < 0.0001), and speed (p < 0.0242), with an equation R2 of .70 (p < 0.0001). Current physical activity level also showed a trend towards being a predictor of VO2 max (p = 0.0538).
The ACSM and ramp equations overestimate VO2max in older adults, excepting the ramp equation in men. Our data indicate that, in addition to mechanical test variables, age, sex, and BMI are important predictors of VO2 max in older adults. This work was supported by the NIH-NIA, Claude D. Pepper Older Americans Independence Center, Grant # 5 P60 AG 11268 and by the NIH-NCRR, General Clinical Research Centers Program Grant # M01-RR-30.