Maximal Oxygen Uptake Validation in Children With Expiratory Flow Limitation

Abstract

A two-test protocol (incremental/ramp (IWT) + supramaximal constant-load (CWR)) to affirm max and obviate reliance on secondary criteria has only been validated in highly fit children. In girls (n = 15) and boys (n = 12) with a wide range of VO 2 max (17-47 ml/kg/min), we hypothesized that this procedure would evince a VO 2 -WR plateau and unambiguous VO 2 max even in the presence of expiratory flow limitation (EFL). A plateau in the VO 2 -work rate relationship occurred in 75% of subjects irrespective of EFL There was a range in RER at max exercise for girls (0.97-1.14; mean 1.06 ± 0.04) and boys (0.98-1.09; mean 1.03 ± 0.03) such that 3/15 girls and 2/12 boys did not achieve the criterion RER. Moreover, in girls with RER > 1.0 it would have been possible to achieve this criterion at 78% VO 2 max. Boys achieved 92% VO 2 max at RER = 1.0. This was true also for HRmax where 8/15 girls' and 6/12 boys' VO 2 max would have been rejected based on HRmax being < 90% of age-predicted HRmax. In those who achieved the HRmax criterion, it represented a VO 2 of 86% (girls) and 87% (boys) VO 2 max. We conclude that this two-test protocol confirms VO 2 max in children across a threefold range of VO 2 max irrespective of EFL and circumvents reliance on secondary criteria.El protocolo que comprende dos test (incremental en rampa (TTI) + carga constante supramaximal) (CCS) aplicado para confirmar el consumo máximo de oxigeno y obviar la dependencia de los criterios secundarios ha sido solamente validado en niñas (n=15) y niños (n=12) bien entrenados, que poseían amplios rangos de VO 2 max (17-47 ml/kg/min). Nosotros hipnotizamos que este procedimiento podría evidenciar una meseta en la relación VO 2 -tasa de trabajo y por lo tanto indicar valores ambiguos de VO 2 max incluso en niños que presentan limitaciones del flujo espiratorio (LFE). La meseta en la relación entre el VO 2 -tasa de trabajo ocurre en el 75% de los sujetos, independientemente de que presenten LFE. El rango de valores en la relación de intercambio respiratorio (RER) se extendió entre 0.97 a 1.14 en niñas (M=1.06±0.04) y entre 0.98 a 1.09 en niños (M=1.03±0.03). De esta forma, 3/15 niñas y 2/12 niños no alcanzaron el criterio de RER para estimar el VO 2 max. Por otra parte, en las niñas que mostraron un RER>1.0 hubiera sido posible alcanzar este criterio con un valor del 78% VO 2 max. Los niños alcanzaron el 92% del VO 2 max con un RER=1.0. Esta respuesta, fue observada también

Verification of Maximal Oxygen Uptake in Obese and Nonobese Children

“…The test was stopped when participants were unable to maintain a cadence of 50 rpm for five seconds despite encouragement. The procedure for the verification test was consistent with previous studies (7, 34). After the first minute, expired air was collected for 30 seconds in polyurethane bags and analyzed as described above.…”

“…We hypothesized that obese children would achieve higher levels V̇O 2 during verification testing when compared with incremental testing because the increased energetic costs of physical activity in obesity could potentially affect performance during an incremental test, with exhaustion occurring prior to attainment of V̇O 2max (19). We also hypothesized that nonobese children would achieve similar levels of V̇O 2 during verification testing when compared with incremental testing based on previous reports (4, 7, 34, 36). …”

“…In the absence of a plateau, secondary criteria such as respiratory exchange ratio (RER) ≥ 1.00, maximal heart rate ≥ 90% of age predicted maximal heart rate, and signs of intense effort such as hyperpnea, facial flushing and grimacing, unsteady gait, and sweating have been suggested (5). However, the use of secondary criteria for validating V̇O 2max significantly underestimate V̇O 2 max in children, which has led researchers to suggest that even these criteria should be abandoned (7, 34). The recommended approach for validating V̇O 2max is to conduct a verification test at a workload that is higher than the highest incremental workload (29).…”

“…Supramaximal verification testing has typically been conducted at 105% of the maximal power achieved during the incremental test, 10 – 15 minutes after the maximal incremental test in nonobese children (7, 34, 36). There are no data comparing incremental and supramaximal verification tests in obese children.…”

“…Hulens et al previously reported that obese adults achieved lower values of minute ventilation (V̇ E ), RER, heart rate and perceived exertion at peak exercise when compared with lean adults, which could make it difficult to determine whether they attained V̇O 2max (19), although similar findings have not been observed in obese children (26). Moreover, as noted above, there are obvious problems associated with the validity of primary and secondary criteria in determining attainment of V̇O 2max during an incremental test, which could lead to incorrectly accepting submaximal V̇O 2 values as V̇O 2max (32, 34). Inaccurate measurement of V̇O 2max could lead to obese children being wrongly labeled as “deconditioned” and they could be offered an exercise prescription of a lower intensity than suitable.…”