Impacts of High-Intensity One-Year Respiratory Muscle Exercise on Respiratory Muscle Force and Dyspnea at Various Body Trunk Angles in a Tetraplegic Patient.

Strong coughing cleans the airways and prevents respiratory diseases. Cough intensity is regulated by respiratory muscle strength, which is improved by high- rather than low-intensity respiratory muscle training. Body trunk angles affect respiratory muscle force and function in healthy adults. Tetraplegic patients generally exhibit respiratory muscle weakness, leading to weak coughing and dyspnea, improved by 6-9 weeks of respiratory muscle exercise. However, the effects of semi-recumbent positions and long-term high-intensity respiratory muscle exercise on respiratory muscle strength and dyspnea in tetraplegic patients remain unclear. A male patient with a C4 spinal cord injury underwent high-intensity inspiratory muscle exercise for one year. We evaluated the abovementioned symptoms and explored the optimal trunk angle and exercise duration. We measured maximal inspiratory and expiratory pressures, respiratory functions such as vital capacity, and dyspnea at 45-degree, 30-degree, and 0-degree (supine) body trunk angles for one year. The inspiratory muscle force was generally stronger at the 45-degree position than in the supine position. In contrast, the supine position showed a trend toward greater respiratory functions and improved dyspnea than the 45-degree position. Inspiratory muscle force tended to strengthen until 6 months and then became stable. Expiratory pressures tended to be greater after 8 months. Vital capacity showed a trend greater at 12 months than at 0 months. Post-activity dyspnea continuously improved for up to 12 months. Thus, maintaining long-term high-intensity exercise and a 45-degree body trunk angle may be beneficial in strengthening inspiratory muscle force and alleviating dyspnea in tetraplegia.