Rating of perceived difficulty scale for measuring intensity of standing balance exercises in individuals with vestibular disorders

BACKGROUND: A method for prescribing the difficulty or intensity of standing balance exercises has been validated in a healthy population, but requires additional validation in individuals with vestibular disorders. OBJECTIVE: This study validated the use of ratings of perceived difficulty for estimation of balance exercise intensity in individuals with vestibular disorders. METHODS: Eight participants with a confirmed diagnosis of a vestibular disorder and 16 healthy participants performed two sets of 16 randomized static standing exercises across varying levels of difficulty. Root Mean Square (RMS) of trunk angular velocity was recorded using an inertial measurement unit. In addition, participants rated the perceived difficulty of each exercise using a numerical scale ranging from 0 (very easy) to 10 (very difficult). To explore the concurrent validity of rating of perceived difficulty scale, the relationship between ratings of perceived difficulty and sway velocity was assessed using multiple linear regression for each group. RESULTS: The rating of perceived difficulty scale demonstrated moderate positive correlations RMS of trunk velocity in the pitch (r = 0.51, p < 0.001) and roll (r = 0.73, p < 0.001) directions in participants with vestibular disorders demonstrating acceptable concurrent validity. CONCLUSIONS: Ratings of perceived difficulty can be used to estimate the intensity of standing balance exercises in individuals with vestibular disorders.