Respiratory muscle training on pulmonary and swallowing function in patients with Huntington’s disease: a pilot randomised controlled trial

Objective: To examine the effects of 4-month of respiratory muscle training on pulmonary and swallowing function, exercise capacity and dyspnoea in manifest patients with Huntington’s disease. Design: A pilot randomised controlled trial. Setting: Home based training program. Participants: Eighteen manifest Huntington’s disease patients with a positive genetic test and clinically verified disease expression, were randomly assigned to control group (n=9) and training group (n=9). Intervention: Both groups received home-based inspiratory (5 sets of 5 repetitions) and expiratory (5 sets of 5 repetitions) muscle training 6 times a week for 4 months. The control group used a fixed resistance of 9 centimeters of water, and the training group used a progressively increased resistance from 30% to 75% of each patient’s maximum respiratory pressure. Main measures: Spirometric indices, maximum inspiratory pressure, maximum expiratory pressure, six minutes walk test, dyspnoea, water-swallowing test and swallow quality of life questionnaire were assessed before, at 2 and 4 months after training. Results: The magnitude of increases in maximum inspiratory (d=2.9) and expiratory pressures (d=1.5), forced vital capacity (d=0.8), forced expiratory volume in 1 second (d=0.9) and peak expiratory flow (d=0.8) was substantially greater for the training group in comparison to the control group. Changes in swallowing function, dyspnoea and exercise capacity were small (d≤0.5) for both groups without substantial differences between groups. Conclusions: A home-based respiratory muscle training program appeared to be beneficial to improve pulmonary function in manifest Huntington’s disease patients but provided small effects on swallowing function, dyspnoea and exercise capacity.