By Bethany B. Barone and Kerry J. Stewart, Johns Hopkins University
The use of absolute versus weight standardized maximal oxygen consumption during fitness testing has been debated, especially in the context of intervention trials that may induce weight change. We recently showed that exercise training-related changes in exercise systolic blood pressure (SBP) were independently predicted by changes in fatness (by waist circumference) and fitness (by VO2peak in mL/min.kg).
Dr. Shephard correctly points out that reductions in weight could increase VO2peak adjusted for weight without absolute increases in fitness and commented on our use of fitness standardized to weight rather than absolute change in fitness. Though our 6-month exercise-only intervention was associated with minimal weight loss compared to controls (-1.8 kg), we did repeat our analysis using change in absolute fitness to address his concerns.
Our original analysis found that each 1.0 ml/kg.min increase in VO2peak and 1.0 cm decrease in waist circumference independently predicted a 1.0 mm Hg decrease in exercise SBP (p=0.04 and p=0.001, respectively). When we repeated this analysis using maximal absolute oxygen consumption, results were consistent with our original report. A 100 ml/min increase in VO2peak was associated with a 1.1 mm Hg decrease in exercise SBP (p=0.057); a 1.0 cm decrease in waist circumference was associated with a 1.2 mm Hg decrease in exercise SBP (>0.001). Therefore, we affirm our original conclusions that increased fitness has a beneficial effect on exercise SBP beyond weight loss.