Verification of Maximal Oxygen Uptake in Obese and Nonobese Children

Abstract

Purpose The purpose of this study was to examine whether a supramaximal constant load verification test at 105% of the highest work rate would yield a higher V̇O2max when compared with an incremental test in 10 – 12 year old nonobese and obese children. Methods Nine non-obese (BMI percentile: 57.5 ± 23.2) and nine obese (BMI percentile: 97.9 ± 1.4) children completed a two-test protocol that included an incremental test followed 15 minutes later by a supramaximal constant-load verification test. Results The V̇O2max achieved in verification testing (Nonobese: 1.71 ± 0.31 and Obese: 1.94 ± 0.47 L/min) was significantly higher than that achieved during the incremental test (Nonobese: 1.57 ± 0.27 and Obese: 1.84 ± 0.48 L/min; P < 0.001). There was no significant interaction (group (i.e., nonobese versus obese) × test (i.e., incremental versus verification)), suggesting that there was no effect of obesity on the difference between verification and incremental V̇O2max (P = 0.747). Conclusion A verification test yielded significantly higher values of V̇O2max when compared with the incremental test in obese children. Similar results were observed in nonobese children. Supramaximal constant-load verification is a time-efficient and well-tolerated method for identifying the highest V̇O2 in nonobese and obese children.

Importance of a verification test to accurately assess V̇O2max in unfit individuals with obesity

“…Bland‐Altman analysis showed error bias of 63 mLO 2 ·min −1 which suggest that GXT routinely underestimate by that magnitude. This bias is lower than the one reported by Bhammar et al, (ie, 118 mLO 2 ·min −1 ) but higher than Sawyer et al, (ie, 40 mLO 2 ·min −1 ). Astorino and DeRevere in active young adults reported negative bias (−54 and −41 mL·min −1 ), indicating that VerT could underestimate GXT .…”

“…Using these parameters, we found high test‐retest reproducibility in VerT in a subset of eight of our untrained MetS individuals with obesity. VerT time to exhaustion (2.1 ± 0.4 minutes; Table ) was similar to previous studies . Thus, a VerT procedure as the present (110% work rate after 15 minutes of recovery and a 2 minutes or warm‐up) seems to be reproducible and valid in unfit MetS individuals with obesity.…”

“…In contrast, sensitivity, which is the ability of GXT to detect a true was very low (23%) due to the numerous false negative (Figures and ). One other study in obese children reports similar values for sensitivity and specificity of GXT (ie, 22% and 44%, respectively) when using VerT . Although GXT had poor combination of sensitivity and specificity in our sample, it is unclear which levels of specificity and sensitivity could be tolerable for assessment.…”

“…These are based on the agreement (or lack of it) between the value measured and the expected from extrapolation of the lineal portion of the work rate‐ relationship. They range from very restrictive as the one initially proposed by Midgley et al to excessively tolerant accepting GXT plateau when reading is only 3% lower than modeled . We have adopted an intermediate restrictive criterion based on the original work by Taylor and Buskirk where a GXT plateau is accepted when the increase in between the next‐to‐last and the maximal work rate is lower than 50% of expected for that increase in work rate.…”

Efficacy of constant load verification testing to confirm VO2max attainment

“…() demonstrated that overweight and obese adults show ‘true’ VO 2 max in response to VER, which suggests that obesity does not affect achievement of VO 2 max. However, recent findings in normal weight and obese children show that VER elicited higher VO 2 max than INC (Bhammar et al ., ). Our data show that compared to more fit individuals, persons classified as low fitness are more likely to reveal lower VO 2 max in response to INC versus VER, as no subject with VO 2 max≥50 ml kg −1 min −1 showed higher VO 2 max in response to VER.…”