Clinical Trial of Exercise in Patients With Spinal Muscular Atrophy (SMA)

Inclusion Criteria: 1. Weakness and hypotonia consistent with the clinical diagnosis of SMA type 3, i.e. having achieved the ability to walk independently 2. Laboratory documentation of homozygous absence of SMN1 exon 7 3. ability to walk at least 25 meters without assistance 4. Aged 8 to 50 years at the time of enrollment 5. Ability to tread the stationary cycle ergometer 6. Written informed consent of patient (if ≥ 18 years of age) or parents/guardian (if \< 18 years of age), and assent for participants who are of minor age. Exclusion Criteria: 1. Inability to walk independently at least 25 meters 2. Any acute co-morbid condition interfering with study participation in the judgment of the investigators within 7 days of enrollment including bacterial infection, viral infectious process, food poisoning, temperature \> 99.0ºF, need for acute treatment or observation due to any other reason, as judged by the investigator; patient can be included after resolution of the acute event 3. Use of investigational medications intended for the treatment of SMA including riluzole, valproic acid, hydroxyurea, oral use of albuterol, sodium phenylbutyrate, butyrate derivatives, creatine, carnitine, growth hormone, anabolic steroids, or agents with known or presumed histone deacetylase (HDAC) inhibition, within 30 days prior to study entry. After signing informed consent, participants may discontinue prohibited medications and will then qualify for a screening visit after the 30 day wash-out period 4. Inability to meet study visit requirements, or cooperate reliably with functional testing and exercise protocol 5. Coexisting medical conditions that contraindicate travel, testing or moderate intensity exercise 6. Pregnant or breastfeeding women, or those intending to become pregnant during the course of the study.