Spinal muscular atrophy (SMA) is a motor neuron disease characterized by an autosomal recessive disorder that is caused by inherited mutations in the survival motor neuron gene (SMN1). SMA causes progressive muscle weakness and atrophy. SMA type III is defined by the onset of symptoms after age 18 months, and patients retain the ability to walk. At the moment, there is no available and effective treatment for patients with SMA. Recent evidence shows that patients with SMA can improve their muscular dystrophies, oxidative capacity (VO2max), and muscle strength through aerobic conditioning exercise.
Karen Lindhardt Madsen, MD from the Neuromuscular Research Unit, University of Copenhagen in Denmark and colleagues, examined the effect of physical training with a cycle ergometer over 12 weeks in a total of eight patients with SMA type III ( the type of SMA that progressively weakens and atrophies the muscle), and nine healthy age- and sex-matched control subjects (all living sedentary lives). SMA III patients were able to walk at least 10 meters with or without assistive devices.
The 12-week intervention training program included 42 and 30 minutes sessions at 65 to 70% maximal oxygen uptake (VO2max,). Before and after each training, the participants were assessed for VO2max, muscle strength, functional tests, and a self-reported questionnaire assessing routine activities.
Results revealed that the 12-weeks training program was able to induce in the patients a 27 ± 3% increase in VO2max . Because of fatigue, one patient dropped out and three other patients felt an enhanced need to sleep.
The team of researchers concluded that cycling could improve VO2max in SMA III without causing muscle damage. However, this modality of physical exercise was found to induce fatigue in SMA III patients. In this regard, the authors suggest that future studies should consider alternative aerobic training methods for patients with SMA III.
The study entitled “Training improves oxidative capacity, but not function in Spinal Muscular Atrophy Type III,” was recently published in the journal Muscle & Nerve.