The 2 min step test: A reliable and valid measure of functional capacity in older adults post coronary revascularisation.

Purpose: Exercise training is the central component in Cardiac Rehabilitation (CR). A baseline assessment of aerobic capacity is paramount for exercise prescription and safety. The Two-Minute Step Test (2MST) has been used to measure aerobic capacity in healthy older adults. However, the reliability and validity of the 2MST in older adults post-coronary revascularisation (CRV) is unknown.

Methods: A prospective observational study was conducted in a single CR centre. Two 2MSTs and one six-minute walk test (6MWT) were completed in a single session. The 2MST measurements were recorded by two raters for each individual. The six-minute walk distance (6MWD) and 2MST steps recorded by both raters were analysed to determine the relationship and agreement between measurements.

Results: Thirty one participants with a median (IQR) age of 66 (62,73) years old were included in the study post CRV. Strong positive correlations were found between steps achieved during the 2MSTs and the 6MWD (r = 0.87, 95% CI 0.82-0.91, p < 0.0001). Excellent inter-rater reliability was demonstrated between raters during the 2MSTs (ICC = 0.999-1.000, p = 0.000). Excellent relative test-retest reliability was demonstrated in both 2MSTs recorded by both raters (ICC = 0.927-0.934, p = 0.000). However, absolute test-retest reliability may have been limited by a learning effect between repeated 2MSTs.

Conclusions: The results of this study indicate that the 2MST may be used as an alternative to the 6MWT as an outcome measure for aerobic capacity in older adults post-CRV. However, a practice trial is recommended at baseline to account for a learning effect.