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Updated: Jan 17, 2026
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Functional Characterization of Endogenously Expressed Human RYR1 Variants
Published on: June 9, 2021
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Exercise capacity in RYR1-related myopathies
Lisa M K Chin1, Joshua J Todd2,3, Irene C Chrismer4,5
1Rehabilitation Medicine Department, National Institutes of Health (NIH) Clinical Center, Bethesda, Maryland, USA.
Orphanet Journal of Rare Diseases
|September 24, 2025
Summary
Exercise capacity is significantly reduced in individuals with RYR1-related myopathies but remains stable over six months. The six-minute walk test correlates with exercise capacity, aiding in personalized exercise plans.
Area of Science:
- Neuromuscular Disorders
- Exercise Physiology
- Genetics
Background:
- RYR1 gene variations cause RYR1-related myopathies, a common congenital myopathy.
- These myopathies lead to skeletal muscle weakness, fatigue, and reduced functional capacity.
- This study investigates exercise capacity in affected adults and children.
Purpose of the Study:
- To assess exercise capacity in adults and children with RYR1-related myopathies.
- To evaluate changes in exercise capacity over a six-month period.
- To examine the relationship between exercise capacity and the six-minute walk test.
Main Methods:
- 32 adults and 16 children with confirmed RYR1-related myopathies participated.
- Cardiopulmonary exercise testing and a six-minute walk test were performed at baseline and six months.
- Outcomes were compared to expected values and analyzed longitudinally.
Main Results:
- Peak exercise outcomes (oxygen uptake, work rate, heart rate) were significantly lower than expected in both groups.
- Peak oxygen uptake was 62% (adults) and 49% (children) of predicted values.
- No significant changes in peak exercise outcomes were observed over six months, but a correlation was found between peak work rate and six-minute walk test distance.
Conclusions:
- Exercise capacity is diminished and stable over six months in individuals with RYR1-related myopathies.
- The six-minute walk test is a valid indicator of peak exercise work rate in this population.
- Exercise capacity testing can inform personalized exercise regimens for RYR1-related myopathies.
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