Abstract:
It has been demonstrated that walking is the most common form of physical activity for adults with intellectual disabilities, including Down syndrome (DS). The pedometer is common measurement tool to quantify steps walked, yet there is little evidence of the psychometric properties for individuals with intellectual disabilities, particularly DS. Thus, this work was to provide reliability and validity evidence to determine if pedometers can be used for adults with DS. The first study addressed the accuracy of spring-levered and piezoelectric pedometers under controlled conditions for adults with and without DS. It was determined that there were significant differences in measurement error between adults with and without DS for both pedometer models. Additionally, piezoelectric pedometers were found to be more accurate than spring-levered pedometers, particularly at slower walking speeds. These differences between pedometer models were also explained by increasing waist-to-hip ratios of individual participants. Absolute error rates for adults with DS were higher than the control group, but may still be acceptable for future use. The second study addressed the reliability and sources of variance in spring-levered and piezoelectric pedometer measurements under free-walking conditions for adults with and without DS. This was conducted using Generalizability (G) theory. Adults with DS demonstrated greater intra-individual variability during the while the control group, conversely, had greater residuals, or unexplained errors. The spring-levered pedometer showed problems with inter-unit variability through substantive variance components. The piezoelectric pedometer demonstrated little systematic error. Additionally, reliability coefficients were calculated for each group and model combination. The piezoelectric pedometer demonstrated higher reliability than the spring-levered based on moderate to high reliability coefficients. Collectively these studies provide evidence that piezoelectric pedometers are more accurate and more reliable than spring-levered pedometers for both adults with and without DS. For future studies measuring walking activity of adults with DS, the use of piezoelectric pedometers is recommended.
