The feasibility of supramaximal verification of peak oxygen uptake of a graded maximal treadmill test in adults with Intellectual Disability

Abstract

Background: Currently used cardiorespiratory fitness tests for adults with an intellectual disability (ID) have not been studied for validity within this group for measuring the cardiorespiratory fitness. There is a need for a valid cardiorespiratory fitness test, for determining health risk factors and evaluating therapy in clinical practice. The gold standard of measuring cardiorespiratory fitness is a maximal exercise test, measuring the maximal oxygen uptake (VO2max). It is not clear if the peak oxygen uptake (VO2peak) of a maximal cardiorespiratory exercise test, like a graded maximal treadmill test (GXTT), represents the true maximal oxygen uptake in adults with ID. A supramaximal exercise test (SET) can be used to verify, if the measured VO2peak reflects a true VO2max. To date it is not known if adults with ID are able and willing to perform both the GXTT and the SET until exhaustion. Aim: To examine three aspects (completion rate, agreement and acceptability) of feasibility of a graded maximal treadmill test combined with a supramaximal exercise test in adults (18-50 years) with ID. Methods: A cross sectional observational design was used, which consisted of 2 sessions. Prior to testing, a 3-step familiarization process was performed (session 1), after which the VO2peak of the GXTT (VO2peakGXTT) and the SET (VO2peakSET) were measured (session 2). The feasibility parameters used in this study were completion rate (through the Rowland criteria of maximal effort), agreement (through intraclass-correlation-coefficient (ICCagreement)) and acceptability (through a custom-made questionnaire). Results: 12 Participants performed the measurement procedure. The completion rate was 75% and the ICCagreement was 0.99 (p<0.000). The questionnaire showed the measuring procedure was acceptable for the participants. Conclusion: This study showed it seems feasible to perform a maximal treadmill test (GXTT) followed by a supramaximal exercise test for adults with ID.