The Balance Intensity Scales for Therapists and Exercisers Measure Balance Exercise Intensity in Older Adults: Initial Validation Using Rasch Analysis

Background: The Balance Intensity Scales (BIS) have been developed to measure the intensity of balance exercise in older adults. Objective: The objective was to determine whether the BIS for therapists (BIS-T) and for exercisers (BIS-E) are unidimensional measures of balance exercise intensity, able to be refined using the Rasch model into a hierarchical item order, and appropriately targeted for the older adult population with a variety of diagnoses in a range of exercise testing settings. Design: This was a scale development study using a pragmatic mixed-methods approach. Methods: Older adult exercisers (n = 108) and their therapists (n = 33) were recruited from a large metropolitan health service and rated balance exercise tasks on the BIS-T and BIS-E in a single session. Results: Scores on both the BIS items and global effort ratings for therapists and exercisers had good correlation and demonstrated unidimensionality. The BIS-T and BIS-E demonstrated a hierarchical distribution of items that fit the Rasch model. The Person Separation Index was moderate (0.62) for the BIS-T but poor (0.33) for the BIS-E. Limitations: The limitations were that therapists in this study underprescribed high-intensity balance tasks. Conclusions: Initial validation of the BIS-T and the BIS-E demonstrated that these scales can be used for the measurement of balance exercise intensity in older adult populations. The BIS-T items and global effort ratings are recommended for use by therapists, and the global effort ratings are recommended for use by exercisers. Ongoing validation of both scales using high-intensity balance task ratings and different populations of older adults is recommended.