Because of their lack of sweat glands individuals with hypohidrotic ectodermal dysplasia (HED) are at particular risk of life-threatening hyperthermia during exercise in a warm environment. In this study, the effects of physical exercise are investigated in boys and male adolescents with X-chromosomally inherited HED as well as age-matched controls, who undergo standardized exertion on a bicycle ergometer at ambient temperatures of 25°C and 30°C. Body core temperature during and after ergometry, heart rate, performance, and serum lactate as a marker of metabolic stress are measured. Subjects with HED are expected to show an endangering rise of body temperature in connection with physical exercise. To clarify, whether novel cooling devices may reduce the likelihood of overheating, the effects of such devices are evaluated at 30°C.

Inclusion Criteria:

• for patients: hypohidrotic ectodermal dysplasia caused by EDA gene mutations
• regular fluid intake prior to the investigation
• written informed consent

Exclusion Criteria:

• acute febrile illness
• acute or chronic heart disease
• arterial hypertension
• gastrointestinal disorders
• implantable electronic devices
• MRI investigation scheduled for the 5 days subsequent to the study
• clinical signs or diagnostic findings of dehydration

subjects with X-chromosomally inherited hypohidrotic ectodermal dysplasia (HED) and age-matched controls