Prader–Willi Syndrome

Prader–Willi syndrome (PWS) is a rare disease with an incidence between 1:10,000 and 1:30,000 and represents a complex neurogenetic disorder. PWS is caused by a defect on chromosome 15 that is present from early pregnancy and leads to altered processes in the diencephalon. Key symptoms of PWS include intellectual disability, hyperphagia, deficiency of growth and sex hormones, muscle hypotonia, and a disordered metabolism. The altered metabolism results in a reduced basal metabolic rate. In addition, affected individuals typically present from birth with a mismatch of higher body fat and lower muscle mass. Combined with uncontrolled, increased food intake, these symptoms often lead to long-standing, severe obesity with pronounced central fat accumulation, with body mass index (BMI) values that may exceed 50. Prolonged severe obesity then results in typical secondary conditions such as cardiovascular and respiratory diseases, type 2 diabetes, and musculoskeletal disorders (e.g., scoliosis, joint disease, and osteoporosis) that are characteristic of PWS.

Both cognitive and motor development in children with PWS are delayed. Alongside generally reduced physical activity, children show limited motor skills, decreased muscle tone and strength, impairments in balance, and reduced endurance—deficits that often persist into adulthood.

A small number of studies have already demonstrated the effectiveness of targeted exercise in improving body composition in people with PWS and show that the muscles of children with PWS respond to specific training stimuli similarly to those of healthy children. Structured training can help patients regulate body weight and compensate for muscular weaknesses. Promoting motor skills is important for managing activities of daily living and reducing the elevated risk of falls. Moreover, improving or maintaining overall physical fitness is a key factor in lowering the risk of secondary diseases.