LAUSR

We studied the accuracy of graded exercise testing (GXT) to assess improvements in maximal oxygen uptake (VO2MAX) with exercise training in unfit individuals with metabolic syndrome (MetS). Forty-four adults with MetS (58±7 years; 36% women; BMI 31.8±4.8 kg·m-2) underwent 4 months of supervised high-intensity interval exercise training. VO2MAX was assessed using GXT followed by a constant-load verification test (VerT) at 110% of the maximal work-rate achieved during GXT. VO2 data from GXT and VerT were compared using repeated measures ANOVA. The mean improvement in VO2MAX following exercise training was similar when using GXT only or VerT. However, before training, 18 subjects achieved a higher VO2MAX during the verification test that was (+159 mLO2·min-1) higher than the GXT (P<0.001). After training, the underestimation of VO2MAX by GXT was reduced but still present (+64 mLO2·min-1). As a result, improvements in VO2MAX following exercise training as assessed using GXT only almost doubled the "real" increase in VO2MAX as measured by VerT in these 18 individuals. In the remaining 26 subjects, GXT scored below VerT only after training (+54 mLO2·min-1; P=0.046). As a consequence, GXT underestimated the actual VO2MAX increases (-49 mLO2·min-1; P=0.013) in these individuals. Assessment of changes in VO2MAX following exercise training using only GXT over-or-underestimates VO2MAX gains in unfit individuals with MetS. Thus, a verification test may be required to 1) identify the highest VO2MAX during a maximal exercise test on a cycle ergometer, 2) accurately quantify the true changes in cardiorespiratory fitness following exercise training in unfit individuals with MetS.