A Cochrane review ¹ included 3 studies with a total of 56 subjects with Down syndrome (aged from 17 to 65 years). The studies included different kinds of aerobic activity: walking/jogging and rowing training. In the meta-analyses, only maximal treadmill grade, a work performance variable, was improved after aerobic exercise training programmes (WMD 4.26 grades (%), 95% CI 2.06 to 6.45). Other variables relative to work performance that could not be combined in a meta-analysis were also improved in the intervention group: maximal test time (P=0.0003), total turns of fan wheel (P=0.02), resistance of ergometer (p=0.003), power knee extension and flexion (p<0.00001), and timed up and go test (p=0.008). No statistically significant differences between intervention and control groups were found in the meta-analyses of VO₂ peak (WMD 0.30, 95% CI 3.17 to 3.77 mL·Kg^-1min^-1), peak heart rate (WMD 2.84, 95% CI 5.05 to 10.73 beats per minute), respiratory exchange ratio (RER) (WMD -0.01, 95% CI -0.06 to 0.04 VCO₂/VO₂), and pulmonary ventilation (WMD 5.86, 95% CI -4.34 to 16.06 L/min). Thirty other outcomes including, oxidative stress and body composition, could not be combined in the meta-analysis. Apart from work performance, trials reported no statistically significant improvements.

Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment and lack of blinding), and by imprecise results (few patients and wide confidence intervals).