Exercise Training as a Therapeutic Potential for Respiratory Muscle Weakness in Patients with Amyotrophic Lateral Sclerosis

PURPOSE Amyotrophic lateral sclerosis (ALS) is a devastating, incurable disease with five year mortality of higher than 95% mainly due to respiratory failure. Our goal was to investigate existing literature with attempts to improve ALS symptoms and mortality. METHODS A systemic search in PUBMED was performed to identify research papers and selected articles published in peer-reviewed journals. RESULTS This review outlined the two major sources of reactive oxygen species (ROS) that plays an important role on respiratory muscle weakness in ALS, which are mitochondria and NADPH oxidase. Previous animal studies have demonstrated that blocking sources of ROS enhanced respiratory muscle function and increased life span. We further discussed multiple therapeutic approaches to slow down the disease progression of ALS patients, including diaphragm pacing and intermittent hypoxia training. These previous approaches have suggested that exercise training might have beneficial impacts on the ALS patients. Regardless, exercise training, in the past years, has not been recommended due to its potential effect on accelerating disease progression. The impacts of training may benefit or harm the individuals depending on the training intensity and type of exercise (i.e. aerobic vs. resistance training). CONCLUSIONS Our systemic review suggests that excess ROS plays an important role in the pathogenesis of ALS, and exercise training might delay disease progression and symptoms. However, training effect of exercise on ALS patients has remained unclear.