Muscular dystrophy is a group of disorders that are characterized by progressive muscle weakening and loss of muscle mass, caused by defects in muscle proteins. Muscular dystrophy is almost always inherited disorders, and so far, no curative treatments exist.

Previous studies have shown that endurance training significantly improves fitness and self-assessed muscle function in a variety of muscular dystrophies. In this study, we wish to investigate whether patients with Bethlem myopathy (a specific form of muscular dystrophy) also benefit from endurance training.

The study consists of two test days, a 10-week training period and five blood tests.

Patients will be required to train, three times per week, for 10 weeks, on a bike ergometer with a specific training intensity, under pulse rate monitoring.

The training period will be flanked by two test days, where we will determine, and compare the patients' muscle strength and fitness level, from before to after the training program. The patients conditioning level will be determined from a 15 minute cycle ergometer test and patients will undergo three functional tests to determine their functional muscle strength.

We will as a safety measure analyze blood tests before, during and after the training program for the muscle enzyme creatine kinase (an indicator of muscle damage) and through adverse effects as reported by patients during weekly telephone-consultations with the Principal investigator.

We anticipate, that Bethlem myopathy patients will have a similar rise in fitness level and functional muscle strength, as that seen in patients with other forms of muscular dystrophy, who undertake a similar training program.

Inclusion Criteria:

• Patients with Bethlem myopathy

Exclusion Criteria:

• Patients with disorders that would confound the interpretation of the effect from training (cardiomyopathy, pregnant women, etc.)
• Patients who are deemed mentally unfit for cooperation with the training program