Training of the Respiratory Muscles in Individuals With Tetraplegia.

Uijl S, Houtman S, Folgering H, Hopman M (Departments of Physiology and Pulmonary Diseases, University of Nijmegen, The Netherlands), Spinal Cord. 1999;37:575-579.

According to recent research, individuals with cervical cord lesions demonstrate decreased lung volumes and pressures and decreased oxygen consumption in comparison with normal individuals. The purpose of this study was to determine the effect of flow-controlled endurance training of the respiratory muscles on respiratory muscle strength and endurance and on overall exercise capacity in subjects with tetraplegia.

Nine subjects (aged 20 to 49 years) with complete or incomplete cervical lesions (C3-7) participated in the study. The study used a crossover design with subjects performing "sham" training for 6 weeks, followed by resisted training for 6 weeks. The subjects served as their own controls. All training occurred twice a day for 15 minutes. Sham training consisted of inspiration through an incentive spirometer, and actual training added inspiratory mouth pressure through the device to equal 70% of endurance pressure ([P.sub.endu]).

Lung function tests, including inspiratory vital capacity (IVC), forced expiratory volume in 1 second ([FEV.sub.1]), and forced inspiratory volume in 1 second ([FIV.sub.1]), were performed at the beginning of the study, after 6 weeks of sham training, and after 6 weeks of actual training. Inspiratory muscle strength was measured at residual volume using maximal inspiratory mouth pressure ([P.sub.imax]). Respiratory muscle endurance was measured using an incremental loading test, with the highest pressure achieved and maintained for 1 minute defined as [P.sub.endu.] Oxygen consumption was measured using a progressive arm ergometry exercise test.

The IVC, [FIV.sub.1], and [FEV.sub.1] were not significantly different before and after sham or real training; [P.sub.endu] increased after sham training and also after real training, whereas [P.sub.imax] remained unchanged. Sham training had no effect on exercise capacity, but actual training demonstrated significant exercise capacity increases ([Vo.sub.2]max).

According to the researchers, the increase in respiratory muscle endurance with a lack of increased muscle strength supports the principle of training specificity. They also believed that the increase in [P.sub.endu] after sham training may represent an increased focus on breathing. They concluded that flow endurance training of the respiratory muscles in patients with tetraplegia appears to result in increased respiratory muscle endurance and improved exercise performance.

Susan Scherer, PT University of Colorado Health Sciences Center Denver, Colo