Orphanet J Rare Dis. 2025 Sep 24;20(1):485. doi: 10.1186/s13023-025-04013-7.
ABSTRACT
BACKGROUND: Pathogenic variations affecting the ryanodine receptor 1 (RYR1) gene may result in a variety of neuromuscular disorders, collectively known as RYR1-related myopathies. Considered the most common form of congenital myopathy, individuals with RYR1-related myopathies may experience skeletal muscle weakness and fatigue, as well as reduced functional capacity. This study examined the exercise capacity in individuals with RYR1-related myopathies during a cardiopulmonary exercise test.
METHODS: Ambulatory individuals (32 adults, 16 children) with genetically confirmed RYR1-related myopathies performed exercise testing on a cycle ergometer and a six-minute walk test at baseline and month six (pre-intervention phase) of a randomized controlled trial (NCT02362425). Outcomes at peak exercise were compared to expected values among the adult and pediatric populations, while longitudinal changes were assessed after six months. Correlations between peak exercise outcomes and the six-minute walk test distance were also examined.
RESULTS: The peak outcomes of oxygen uptake, work rate and heart rate at baseline were lower (all p < 0.001) than expected in both adults and children. Peak oxygen uptake expressed as percent predicted was 62 ± 20% and 49 ± 24% in adults and children, respectively. No changes were observed across six months for peak exercise outcomes in either group. A moderately strong positive correlation was observed for peak work rate and six-minute walk test distance among adults (rs = 0.75, p < 0.001) and children (rs = 0.64, p = 0.008).
CONCLUSION: Exercise capacity is diminished in adults and children with RYR1-related myopathies yet remains stable over six months. The six-minute walk test distance had a direct relationship to peak exercise work rate in adults and children. Exercise capacity testing may be informative for individualizing exercise regimens for persons with RYR1-related myopathies. This study was registered with www.
CLINICALTRIALS: gov (NCT02362425) on February 12, 2015.
PMID:40993798 | DOI:10.1186/s13023-025-04013-7
