Inspiratory muscle training improves aerobic capacity and pulmonary function in patients with ankylosing spondylitis: a randomized controlled study

Objective: To evaluate the impact of inspiratory muscle training on aerobic capacity and pulmonary function in patients with ankylosing spondylitis.

Design: Randomized controlled study.

Setting: Rheumatic Rehabilitation Centre.

Subjects: A total of 54 ankylosing spondylitis patients, all males, were randomized to a conventional exercise training associated with an inspiratory muscle training group, or to a conventional exercise training group.

Interventions: Group 1 (27 patients) performed eight weeks of conventional exercise training (supervised weekly group sessions followed by a home-based exercise programme) associated with inspiratory muscle training sessions. Group 2 (27 patients) received eight weeks of conventional exercise training only.

Main measures: Resting pulmonary function (forced vital capacity - FVC, forced expiratory volume in one second - FEV1); effort ventilatory efficiency (lowest ventilatory equivalent ratio for oxygen and carbon dioxide - VE/VO2 and VE/VCO2) and aerobic capacity (peak oxygen uptake - VO2peak) were assessed at baseline and after eight weeks of exercise-based intervention.

Results: After eight weeks follow-up, patients in Group 1 had a significant increased chest expansion and VO2peak compared with Group 2 (3.6 ±0.8 cm vs. 3.2 ±0.5 cm, P = 0.032; 2.0 ±0.5 l/min vs. 1.8 ±0.3 l/min, P = 0.033). There were no significant differences of spirometric measurements, except FVC which significantly improved in patients who performed inspiratory muscle training (82.7 ±5.1% vs. 79.5 ±3.5%, P = 0.014). VE/VCO2 also improved significantly in Group 1 (26.6 ±3.6 vs. 29.2 ±4.7, P = 0.040).

Conclusions: Ankylosing spondylitis patients who performed eight weeks of inspiratory muscle training associated to conventional exercise training had an increased chest expansion, a better aerobic capacity, resting pulmonary function and ventilatory efficiency than those who performed conventional exercise training only.