To compare three equations developed to predict VO2 among patients diagnosed with one of two chronic diseases: essential hypertension (HTN), and fibromyalgia (FM). The equations included the American College of Sports Medicine (ACSM) equation, the FAST equation developed from the Fitness and Arthritis in Seniors Trial (FAST), and an equation developed by Foster et al.
One hundred twenty-two HTN subjects and 68 FM subjects completed a maximum exercise test according to the Duke/Wake Forest protocol. Measured peak VO2 was then compared with the VO2 predicted by the ACSM, FAST and FOSTER equations, using several statistical methods.
The ACSM equation overpredicted peak VO2 in the HTN group by 10.0 +/- 4.0 mL/kg-1/min-1, and in the FM group by 8.6 +/- 4.9 mL/kg-1/min-1 (P < 0.0001). The FAST equation, however, underestimated peak VO2 by 1.5 +/- 4.2 mL/kg-1/min-1 (P < 0.01) and 1.0 +/- 3.3 mL/kg-1/min-1 (P < 0.0001) in the HTN and FM groups, respectively. The FOSTER equation overestimated peak VO2 by 2.3 +/- 3.6 mL/kg-1/min-1 in the HTN group and by 2.1 +/- 3.5 mL/kg-1/min-1 in the FM group (P < 0.0001). A large degree of variability was found for each of the equations.
Results of this investigation indicate that all three equations produced peak VO2 values that were statistically different from measured values. Although the ACSM equation overestimated VO2 by more than 2 metabolic equivalents (METs) in each patient group, both the FAST and FOSTER equations produced differences that were less than 1 MET. Further research is needed to examine the FAST and FOSTER equations among other patient populations and with other exercise protocols.