Study design: An experimental cross-sectional design.
Objectives: To evaluate whether training of the innervated respiratory muscles in individuals with a (partial) cervical spinal cord injury will improve the strength and endurance capacity of these muscles and the exercise performance in these individuals.
Setting: Department of Physiology and Pulmonary diseases, Nijmegen, The Netherlands.
Method: In this study nine individuals with tetraplegia (C3 C7) performed a target flow endurance training of the inspiratory muscles, twice a day for 15 min. First, the subjects performed a 'sham' training for 6 weeks with no appreciable resistance, after that they performed a 'real' training for 6 weeks with a resistance of 70% of the maximal endurance capacity of the inspiratory muscles. The training was evaluated at 0, 6 and 12 weeks by the following tests: (1) the slow Inspiratory Vital Capacity (IVC) and the Forced Inspiratory and Expiratory Volumes over 1 s (FIV1 and FEV1); (2) the Maximal Inspiratory Mouth Pressure (Pimax) and the Endurance Pressure (Pendu) and (3) a maximal arm-cranking exercise test.
Results: After the sham training, the Pendu was increased from 3.98 to 4.71 kPa with a P-value of 0.05. The sham training had no influence on any of the other variables. The real training had no effect on the IVC, FIV1, FEV1 and Pimax, however, increased the Pendu from 4.71 to 6.16 kPa (P=0.01), representing the respiratory muscle-endurance capacity. The oxygen consumption (VO2 peak) in the maximal exercise test improved from 0.87 to 0.98 l/min (P = 0.05).
Conclusion: The results of the study indicate that training of the respiratory muscles results in an enhanced endurance capacity of these muscles and a concomitant increase in the aerobic exercise performance.