Work capacity is an important predictor of declining health or physical function, and of mortality, and is commonly measured as peak oxygen consumption. Peak oxygen consumption is very low in individuals with Down syndrome, the most prevalent genetic cause of intellectual disability. Previous research suggests individuals with Down syndrome may experience a double disadvantage when they are exercising: they may not be able to increase cardiac output sufficiently and they may not be able to allocate adequate blood flow to the working muscles. The aim of this research proposal is therefore to investigate the responses in central and peripheral blood flow regulation and cardiac autonomic function to exercise training in individuals with DS. Additionally the effects of exercise on gait, balance and attitude towards exercise in individuals with DS are investigated.