The reliability of measuring muscle strength in adults with an intellectual disability

Background: Muscle strength is an important factor of overall fitness. The aim of this study was to assess the reliability of a muscle strength measurement of the leg extension, the maximal voluntary contraction (MVC), for adults with an intellectual disability (ID) with cardiovascular disease (CVD) risk factors.

Method: Twenty-four adults with a mild or moderate ID with at least one CVD risk factor (diabetes, hypertension, dyslipidaemia, and/or overweight/obesity) performed the MVC test of the leg extension twice. Each MVC test contains at least three measurements. If one measurement was >10% lower than the highest measurement an extra measurement was performed, with a maximum of five measurements per test. The MVC was measured with a Handheld Dynamometer (Microfet 2) according to the break-method.

Results: The reliability will be presented as the association between both MVC tests of the leg extension with the intra class correlation coefficient (ICC agreement). Furthermore, the Bland and Altman plot will be presented to display the Limits of Agreement between both MVC tests.

Conclusion: The results from this study can be used when measuring muscle strength in future research or in daily practice in adults with ID.