Verification of the maximal oxygen consumption using a supra-maximal stress test on obese children

Abstract

Aims: To study the usefulness of a supra-maximal stress protocol to confirm the achievement of a maximal oxygen consumption in cardiopulmonary stress tests amongst obese children.

Methods: It is a descriptive transversal study carried out upon obese children from 6 to 14 years old. An ergospirometry is carried out on them using a treadmill with an incremental maximal stress protocol and after 15 minutes of rest the supra-maximal stress protocol is applied with 105% of the intensity previously obtained.

Results: A total of 24 obese children (15 male,62.5%) were studied, with an average age of 10.98 years old (±2.18) and an average BMI of 27.44 (±3.31). A plateau was not found for the oxygen consumption in any instance. A total of 19 (79.16%) children fulfilled the classic criteria of maximal stress. The average VO₂peak was 2.20 l/min (±0.57), RER 1.16 (±0.13), Hrmax% 91.95 (±5.18). In the supra-maximal test, the VO₂peak was 2.15 l/min (±0.54), RER 1.05 (±0.11) and Hrmax% 92.42 (±7.83). Seven cases were found with a VO₂peak greater in the supra-maximal test (an average difference of 0.08 l/min), (p≤0.005), despite two of them having fulfilled the classic criteria of maximal stress. Of those that did not fulfil the criteria of maximal stress, there were six cases where the supra-maximal peak of VO₂ did not surpass that of the maximal stress test.

Conclusions: The execution of a supra-maximal stress test after a period of rest after a maximal stress test is feasible amongst obese children. The classic criteria that define the success of the VO₂max can be inadequate for this group, thus, carrying out a supra-maximal stress test would be useful in order to verify it.