Purpose: There is a need for valid and reliable clinical assessment tools to assess cardiorespiratory fitness (CRF) levels in adolescents with autism. Therefore, this study aimed to examine the concurrent validity and test-retest reliability of the Astrand-Rhyming Test (ART) in this population.
Materials and methods: 45 adolescents with autism aged 12-18 years (n = 32 males, 14.47 ± 1.79 years) performed the ART twice (test-retest reliability) and completed a maximal cardiopulmonary exercise test (CPET) (concurrent validity). Reliability parameters included Pearson correlations, intraclass correlation coefficients (ICCs), standard error of measurements (SEM), minimal detectable changes (MDC), coefficients of variation, paired sample t-tests, linear regressions and Bland-Altman plots. The concurrent validity was evaluated with Pearson correlations, ICCs, paired sample t-tests, linear regressions and Bland-Altman plots.
Results: Strong test-retest reliability (r = 0.84-0.85, ICC = 0.84-0.85) was found for the ART, but the wide limits of agreement intervals suggest the presence of substantial variability. The large SEM (4.73-5.08 mL/kg/min) and MDC (13.20-14.07 mL/kg/min) values suggest lower absolute reliability. Moderate to strong levels of association (r = 0.74-0.75) and agreement (ICC = 0.59-0.66) were found between estimated (ART1) and measured (CPET) VO2 max levels, but significant systematic differences (5.71-8.82 mL/kg/min) were observed.
Conclusion: The ART is an accessible and promising method to monitor submaximal CRF levels over time but is less appropriate to estimate maximal CRF levels in this population.
Keywords: Autism; VO2 max; cardiorespiratory; cycle ergometer; reliability; submaximal; validity.
Adolescents with autism are at increased risk of exhibiting low cardiorespiratory fitness (CRF) levels and as a result, placing them at risk for poor physical and mental health outcomes.In clinical practice, the CRF levels of this population should be screened and monitored routinely to identify those at risk and most likely to benefit from a targeted intervention.A submaximal exercise test appears to be feasible in adolescents with autism.The Astrand-Rhyming Test shows good reliability to monitor submaximal CRF levels over time, but is less appropriate to estimate maximal CRF levels in adolescents with autism.The use of the age correction factor of the Astrand-Rhyming Test nomogram is not required to adequately estimate CRF levels in adolescents with autism.