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

Abstract 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.