Maximal oxygen uptake validation in children with expiratory flow limitation

Area of Science:

• Pediatric Exercise Physiology
• Cardiorespiratory Fitness Assessment
• Sports Science

Background:

• Accurate measurement of maximal oxygen uptake (VO2max) is crucial for assessing cardiorespiratory fitness in children.
• Existing protocols often rely on secondary criteria (e.g., respiratory exchange ratio, heart rate max) which can be unreliable.
• A two-test protocol combining incremental/ramp (IWT) and supramaximal constant-load (CWR) exercise has shown promise but requires further validation across diverse fitness levels and conditions.

Purpose of the Study:

• To validate a two-test protocol (IWT + CWR) for confirming VO2max in children with a wide range of fitness levels.
• To determine if this protocol can reliably establish VO2max despite the presence of expiratory flow limitation (EFL).
• To assess the protocol's effectiveness in obviating reliance on secondary criteria such as respiratory exchange ratio (RER) and heart rate max (HRmax).

Main Methods:

• A cohort of 27 children (15 girls, 12 boys) with VO2max ranging from 17-47 ml/kg/min underwent a two-test protocol (IWT + CWR).
• The study investigated the occurrence of a VO2-work rate plateau and the achievement of unambiguous VO2max.
• The influence of expiratory flow limitation (EFL) on the results was examined, alongside the attainment of established RER and HRmax criteria.

Main Results:

• A VO2-work rate plateau was observed in 75% of participants, irrespective of EFL.
• Secondary criteria like RER and HRmax were not consistently met, potentially leading to rejection of VO2max in a significant proportion of participants if relied upon.
• The two-test protocol successfully confirmed VO2max across a threefold range of fitness levels and in the presence of EFL.

Conclusions:

• The two-test protocol (IWT + CWR) is effective in confirming VO2max in children across a broad spectrum of fitness.
• This protocol circumvents the need for secondary criteria, providing a more robust assessment of cardiorespiratory fitness.
• The findings support the use of this protocol for accurate VO2max determination in pediatric populations, even when EFL is present.