Adults with Down syndrome have reduced cardiac response after light exercise testing

OBJECTIVE: Physical fitness is reduced in adults with Down syndrome (DS). The present study was conducted to elucidate the exercise response in adults with DS. DESIGN: Case controlled before-after trial. SETTING: Residential centre for people with intellectual disabilities. PARTICIPANTS: 96 Adults with DS, 25 non-DS adults with an intellectual disability, 33 controls. INTERVENTIONS: Echocardiography to exclude heart defects and to measure cardiac index (CI) in the supine position, supine position with raised legs, and following ten knee bends. MAIN OUTCOME MEASURE: Exercise testing RESULTS: At rest, mean CI was not significantly different between persons with DS and controls (2.3 vs. 2.4 l/min/m(2), p = 0.3). However, mean CI after exercise was significantly lower in DS (2.9 vs. 3.7 l/min/m(2), p < 0.001) and mean CI increase from rest to exercise was more than 50% lower in DS. On the contrary, CI after exercise was similar among controls and non-DS adults with an intellectual disability. Significantly lower stroke volumes in DS were found with insufficient heart rate response. CONCLUSIONS: CI at rest was similar in adults with DS and controls; however persons with DS have a diminished cardiac response to exercise. Stroke volumes were significantly lower in DS during exercise and a compensated heightened heart rate was absent.