Older adults requiring long-term care will experience age-associated deterioration of the quality and quantity of skeletal muscle if no interventions are performed. Long-term training is considered a typical intervention method and is effective for improvement of both muscle quantity and physical function. However, how such training affects muscle quality [i.e., fat-to-muscle ratio as determined by echo intensity (EI)] in older adults requiring long-term care remains unclear. The purpose of this study was to investigate the effects of a 12-month physical training intervention on the quality and quantity of skeletal muscle, physical function, and blood chemistry in older adults requiring long-term care. Seventeen older adults requiring long-term care (Tr-group) and 15 healthy older adults (Cont-group) participated in this study. Patients in the Tr-group performed exercises consisting of resistance and endurance training once or twice a week for 12 months. The EI and muscle thickness of the thigh were calculated from the rectus femoris and biceps femoris using B-mode transverse ultrasound images. Physical functions (isometric knee extension peak torque, sit-to-stand test, 5-m normal/maximal speed walking, handgrip strength, and timed up and go test) and blood lipid components including adipocytokines were measured at three points, i.e. baseline and 6 and 12 months after. The thigh EI was significantly lower after 6 months of training than baseline, and it returned to the initial level after 12 months of training (baseline, 70.2 ± 8.3 a.u.; 6 months, 64.1 ± 11.2 a.u.; 12 months, 72.3 ± 7.2 a.u.). The thigh muscle thickness, 5-m maximal speed walking, and knee extension torque were significantly improved after 12 months of training (P < 0.05). The blood chemistry parameters did not significantly change. These results demonstrate that a 12-month training intervention contributes to improvement of muscle quantity and function with tentative changes in muscle quality but has no effect on blood chemistry in older adults requiring long-term care. We conclude that this type of training has the potential to restore the muscle functional abilities of older adults requiring long-term care.