Oxygen uptake plateau during maximal treadmill exercise in children

Area of Science:

• Pediatric Exercise Physiology
• Sports Science
• Cardiorespiratory Fitness Assessment

Background:

• The "plateau" in oxygen uptake (VO2) is a common criterion for defining maximal oxygen uptake (VO2max) during progressive exercise tests in adults.
• However, studies in children suggest this plateau is observed less frequently, raising questions about its applicability in younger populations.
• Variability in VO2 plateau occurrence may be influenced by subject effort, aerobic fitness, and nonaerobic performance.

Purpose of the Study:

• To investigate the factors contributing to the variability of VO2 plateau achievement in children aged 7 to 10 years during treadmill exercise.
• To determine if subject effort, aerobic fitness, or nonaerobic performance can predict the presence or absence of a VO2 plateau.
• To assess the utility of the VO2 plateau as a criterion for defining VO2max in this pediatric age group.

Main Methods:

• Fifteen children (ages 7-10 years) underwent a progressive treadmill walking test to exhaustion using a ramp protocol.
• Maximal oxygen uptake (VO2max) was assessed, and a VO2 plateau was defined using a specific criterion (change in VO2 < 2 SD below the mean of previous submaximal increases).
• Aerobic fitness was evaluated, alongside nonaerobic measures including a 50-yard sprint and vertical jump test.

Main Results:

• Only 33.3% (5 out of 15) of the children demonstrated a VO2 plateau according to the defined criteria.
• No significant differences were found in peak VO2, heart rate, or respiratory exchange ratio between children who achieved a plateau and those who did not.
• Performance on speed and leg power tests was also similar between the plateau and non-plateau groups.

Conclusions:

• Subject effort, aerobic fitness, and nonaerobic factors do not appear to explain why some children exhibit a VO2 plateau during exercise testing while others do not.
• The findings suggest that a VO2 plateau should not be used as a mandatory criterion for establishing VO2max in children aged 7 to 10 years during treadmill assessments.
• Alternative or supplementary criteria may be necessary for accurately determining maximal oxygen uptake in pediatric populations.