Abstract Mendonca GV, Pereira FD, Fernhall B. Effects of combined aerobic and resistance exercise training in adults with and without Down syndrome. Objective To determine whether adults with Down syndrome (DS) could improve their submaximal and peak exercise capacity, as for adults without disabilities, after 12 weeks of combined (aerobic and resistance) exercise training. Design Prospective study comparing the effects of a 12-week combined exercise program on submaximal and peak exercise capacity of adults with and without DS. Setting University facilities. Participants Participants with DS (n=13; mean ± SD age, 36.5±5.5y) and participants without disabilities (n=12; mean age, 38.7±8.3y). Interventions Combined exercise training for 12 weeks. Endurance training was performed 3 days a week for 30 minutes at 65% to 85% of peak oxygen consumption (V o2 peak). Resistance training was prescribed for 2 days a week and consisted of 2 rotations in a circuit of 9 exercises at 12-repetition maximum. Main Outcome Measures Submaximal and maximal graded exercise tests with metabolic and heart rate measurements. Walking economy and V o2 peak were considered the main outcomes. Results Participants with DS and those without disabilities showed similar values for body mass index and relative fat mass at pre- and posttraining periods. Walking economy and V o2 peak overall were lower in participants with DS than participants without disabilities ( P <.05). Training improved walking economy and V o2 peak in participants with DS and those without disabilities ( P <.05); additionally, the magnitude of changes induced by training was similar between groups. Conclusions Overall, a 12-week combined exercise regimen induced gains of similar magnitude between adults with and without DS for submaximal and peak exercise capacity.