Validation of the step test and exercise prescription tool for adults

Canadian clinical practice guidelines for the management of diabetes highlight the value of physical activity for improving clinical markers and risk factors for diabetes. The use of tools like the Step Test and Exercise Prescription (STEP) in clinical practice facilitates chronic disease management and prevention through the promotion of healthy physical activity. The validity and reliability of STEP has been established previously for use with adults 65 to 85 years of age. The purpose of this study was to test the validity of the prediction equation for VO₂max from the STEP tool for use with adults older than 65 years.

Forty participants completed both the predictive self-paced VO₂max stepping protocol from the STEP tool, and a maximal graded exercise treadmill test with breath-by-breath analysis of expired gases. Tests were completed in random order, and participants rested between tests until blood pressure returned to baseline.

The average age of the sample was 43±14 years. There was a strong relationship between predicted VO₂max from STEP and direct measures of VO₂max from the maximal treadmill test in the present study (r=.78, p<0.001). Bland-Altman analysis demonstrated statistical agreement between tests, although there was systematic overestimation of 6.4 mL/kg/min.

STEP is an evidence-based cardiorespiratory fitness assessment and exercise prescription tool appropriate for use by various health professionals in clinical practice. The prediction equation for VO₂max from the STEP tool is valid for use with adults 18 to 85 years of age. However, more research is warranted to explore age corrections to the prediction algorithm among younger adults.