Metabolic myopathies are genetic diseases, usually inherited, that affect the body’s muscles. Some people with a metabolic myopathy (muscle disease) develop weakness; others tire easily with exercise or physical activity, suffer muscle pain after physical effort, and/or experience severely swollen and tender muscles. These symptoms occur when muscle cells don’t get enough energy. Without enough energy, the muscle lacks enough fuel to work properly.
Most metabolic myopathies are genetic and tend to occur within families. They can appear at any age in those who inherit the disease. Either a parent or another relative may have been symptomatic. However, metabolic myopathies can develop in a person with no family history of the condition.