OBJECTIVE: To evaluate the effect of an upper-body exercise program on cardiorespiratory fitness in older adults with hip fracture during inpatient rehabilitation. DESIGN: Randomized controlled trial using a convenience sample. SETTING: An inpatient rehabilitation unit. PARTICIPANTS: Twenty older patients (age, 81.3+/-7.2y; 14 women). INTERVENTION: Patients were randomly assigned to a control group (n=10) or a training group (n=10). Both groups attended physical and occupational therapy sessions 5 times a week during rehabilitation (mean length of stay, 32.9+/-5.3d). Patients in the training program used an arm crank ergometer 3 times a week for 4 weeks. MAIN OUTCOME MEASURE: Peak oxygen consumption (Vo(2)peak). RESULTS: Vo(2)peak increased significantly in the training group (8.9+/-1.4 to 10.8+/-1.7mL x kg(-1) x min(-1)) and did not change in the control group (8.9+/-1.2 to 8.8+/-1.6mL x kg(-1).min(-1)). At discharge, both groups were significantly improved in all functional outcome measures (Timed Up & Go [TUG] test, Berg Balance Scale [BBS], FIM instrument, two-minute walk test [2MWT], and ten-minute walk test [10MWT]). The training group performed significantly better in mobility (TUG, 2MWT, 10MWT) and balance (BBS) compared with the control group. There was a significant correlation between Vo(2)peak and the 2MWT (r=.81) and 10MWT (r=.85) in the training group at discharge. CONCLUSIONS: The upper-body exercise program had a significant effect on aerobic power. Our results suggest that aerobic endurance exercise should be integrated into standard rehabilitation to enhance patients' aerobic fitness and mobility after hip fracture surgery.