Accuracy of the prediction equation for the determination of maximum heart rate in adults with Down syndrome.

BACKGROUND: The purpose of the study was to determine if the regression formula developed for the prediction of maximum heart rate (HR) is valid for adults with Down syndrome (DS).

METHODS: Thirty-six adults with DS (31.7 ± 6.8 years; 20 men, 16 women) completed a maximal aerobic test. Maximum HR and VO2 peak were measured directly on a motorised treadmill with a metabolic analyser. Predicted HR was estimated with the regression equation developed for individuals with DS (Fernhall et al. 2001). Differences between measured versus predicted maximum HR were assessed with a dependent T-test and the relationship with Pearson correlational analyses. Agreement was assessed with Bland-Altman analysis.

RESULTS: There was a significant difference between directly measured maximum HR and predicted maximum HR (P < 0.01). There was no significant relationship between these variables. Bland-Altman analysis indicated that there was measurement bias (+4.7) and large limits of agreement (+26.7 and -17.4) between measured and predicted maximum HR. The Bland-Altman plot also demonstrated the presence of heteroscedasticity.

CONCLUSIONS: The results indicate that the regression formula developed for individuals with DS was not accurate in this sample of DS adults aged 19 to 46 years. Future studies should develop different prediction equations for more specific age and body mass index categories for individuals with DS.