Comparison of respiratory muscle training methods in individuals with motor complete tetraplegia

To compare the effects of inspiratory resistance training (IRT) and isocapnic hyperpnea (IH) versus incentive spirometry (placebo) on respiratory function, voice, and quality of life in individuals with motor complete tetraplegia.

In this randomized controlled trial, 24 individuals with traumatic, motor complete (AIS A) tetraplegia (C5-C8), 6 to 8 months post injury, were randomly assigned to 1 of 3 groups. They completed either 90 repetitions of IRT, 10 minutes of IH, or 16 repetitions of placebo training in 32 supervised training sessions over 8 weeks. Before and after the training period, the following tests were performed: bodyplethysmography, inspiratory and expiratory muscle strength, subjective breathing parameters using the visual analogue scale (VAS), voice measurements, and an adapted SF-12 quality of life questionnaire. A Friedman test and Cohen's effect sizes for IRT and IH versus placebo were calculated for differences between pre- and posttraining values.

Compared to placebo training, IRT showed high effect sizes for inspiratory muscle strength (d = 1.19), VAS values of "cleaning the nose" (d = 0.99), and the physical component of subjective quality of life (d = 0.84). IH compared to placebo training showed only medium and low effect sizes. The Friedman analysis showed a significant effect for IRT versus placebo on inspiratory muscle strength (P = .030). Neither all other parameters of respiratory function nor voice measurements, subjective breathing parameters, or quality of life were significantly improved by one of the tested training methods.

In individuals with motor complete tetraplegia, inspiratory muscle strength can be improved by IRT. Therefore, IRT is advantageous compared to IH for this group of patients and during the first year post injury.