Welcome to Study of the Week from Patient Worthy. In this segment, we select a study we posted about from the previous week that we think is of particular interest or importance and go more in-depth. In this story we will talk about the details of the study and explain why it’s important, who will be impacted, and more.
If you read our short form research stories and find yourself wanting to learn more, you’ve come to the right place.
This week’s study is…
Aerobic exercise elicits clinical adaptations in myotonic dystrophy type 1 patients independently of pathophysiological changes
We previously published about this research in a story titled “12 Weeks of Exercise Increased Fitness in Myotonic Dystrophy Patients” which can be found here. The study was originally published in The Journal of Clinical Investigation. You can view the full text of this study here.
This research team was affiliated with McMaster University.
What Happened?
Myotonic dystrophy is a neuromuscular disorder and a form of muscular dystrophy in which the skeletal muscles progressively atrophy over time, along with cardiorespiratory issues and muscle weakness. Prior studies of myotonic dystrophy type 1 mouse models have suggested that exercise can improve muscle condition, but the benefits for human patients have not been well established; in fact, some physicians who treat myotonic dystrophy patients advise them to avoid exertion to prevent potential worsening of muscle declines. This study sought to understand if aerobic exercise could have benefits for human patients living with type 1 myotonic dystrophy.
11 people living with myotonic dystrophy type 1 (DM1) were recruited for the study. These participants completed a twelve week cycling exercise program. As part of this program, the patients cycled for 35 minutes three times per week. These patients, along with a control group, were matched for age, height, weight, and body mass index. The researchers found that patients experienced at 32 percent increase in overall fitness. While the program improve fitness and function, it did not result in increased muscle strength.
Cycling did increase muscle mass in patients, however. Overall, the researchers concluded that the cycling program conferred multiple metabolic, physical, and clinical benefits for myotonic dystrophy patients. The scientists also point out that the cellular and molecular changes observed do not align with results seen in studies with mouse models, and suggest that mitochondrial function could play a larger role in the disease mechanism than previously thought.
A six minute walk test indicated that patients were able to travel further after the completion of the exercise program than before.
About Myotonic Dystrophy
Myotonic dystrophy is a form of muscular dystrophy. Its onset is later than many other forms, often beginning in the 20s and 30s (though it can begin at any time). In this long term disorder, the muscle systems contract and are unable to relax. The disease comes in two main forms: type 1, which is usually more severe and linked to mutations affecting the DMPK gene, and type 2, which is caused by mutations of the CNBP gene. Symptoms include progressive muscle weakness, muscle atrophy, heart problems, intellectual disability, cataracts, sleep apnea, and insulin resistance. Men may experience infertility and early balding. Muscle problems often begin in the feet, hands, neck, or face. There are no disease altering therapies for myotonic dystrophy, and treatment focuses on managing symptoms and complications. Common measures include pacemakers, non-invasive ventilation, and mobility aids such as braces or a wheelchair. The disease is estimated to affect around 30,000 people in the US. To learn more about myotonic dystrophy, click here.
Why Does it Matter?
The results of this study suggest that people living with myotonic dystrophy should be performing aerobic exercise on a regular basis, and that doing so has the potential to slow declines in muscle function and fitness. These results also cast serious doubt on any physicians that are discouraging their patients from exercising.
“…Exercise appears to be safe and well-tolerated by patients, as suggested by blood markers and muscle histopathology examination.”
While this study is admittedly limited by its small sample size of only eleven patients, the results nevertheless appear to provide an accessible and reliable method for patients to at least partially mitigate the progression of myotonic dystrophy loss-of-function. While more research with a greater number of patients is warranted, these findings nevertheless have important implications for the management of myotonic dystrophy.
