Abstract
BACKGROUND: Exercise therapy is recommended for patients with amyotrophic lateral sclerosis (ALS), but its effects on muscle mass and intramuscular conditions remain unclear. In recent years, ultrasonography has enabled the simple and non-invasive estimation of muscle mass and intramuscular conditions. This study aimed to investigate the short-term effects of exercise therapy on muscle characteristics in patients with mild-to-moderate ALS using ultrasonography. METHODS: Ambulatory patients with ALS and an ALS Functional Rating Scale-Revised (ALSFRS-R) score of ≥30 underwent moderate-intensity exercise therapy for 3-4 weeks. Primary outcome measures included muscle strength (handgrip strength (HGS) and ankle dorsiflexion strength (ADFS)), muscle thickness (MT), echo intensity (EI), and the ratio of muscle strength to muscle thickness for both the forearm muscles and the tibialis anterior muscle. The Bayesian Wilcoxon signed-rank test was used to compare outcomes before and after the intervention. RESULTS: Six consecutive patients with ALS (median age: 75.5 years; three males (50%) and three females (50%); four with bulbar onset (66.7%) and two with upper limb onset (33.3%)) were included. Following the intervention, the muscle thickness of the forearm muscles and the tibialis anterior muscle decreased. However, qualitative muscle characteristics were partially maintained or improved: the echo intensity of the forearm muscles was maintained, and the ratio of ankle dorsiflexion strength to muscle thickness of the tibialis anterior muscle showed a large increase. CONCLUSION: In patients with mild-to-moderate ALS, exercise therapy resulted in short-term qualitative changes in muscle, while a concurrent reduction in muscle mass may have attenuated these effects. The benefits of exercise therapy may have been counteracted by muscle mass loss, suggesting the need for future studies to investigate the combined effects of exercise and nutritional therapy on muscle characteristics and activities of daily living (ADL).