Effects of exercise, dietary protein, vitamin D, and calcium on physical functioning among middle-aged and older adults
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Exercise and diet may preserve muscle mass and bone health, thereby preventing age-related functional decline among older community-dwelling subjects. We used data from two studies to examine effects of exercise administered through a home-based program for hip fracture patients and the effects of dietary protein, vitamin D, and calcium on physical functioning in older adults. In the Health and Independence Post-Rehabilitation (HIP) study, the effects of a home-based exercise program (vs. attention-based control) (n=232) on functional recovery following hip fracture was assessed using two standardized physical performance batteries. In a sub-analysis (n=56), we evaluated the effects of food frequency questionnaire-derived protein, calcium, and vitamin D intakes on these outcomes. In the Framingham Offspring Study (FOS), dietary protein, calcium, and vitamin D intakes were measured using two sets of 3-day diet records. Physical functioning over 12 years was measured using the Rosow-Breslau and Nagi scales. In the HIP study, the exercise intervention led to significant improvement in physical performance at 6 months for all primary endpoints [(SPPB (P<0.001), AMPAC Mobility Function (P=0.01) and Daily Activity (P=0.01). However, we found no beneficial effects of dietary protein, calcium, or vitamin D on physical functioning. In the FOS, Cox proportional hazard’s models were used to estimate risk of functional decline over 12 years, adjusting for potential confounding by age, sex, education, physical activity, cigarettes per day, height, and energy intake. Subjects consuming ≥ 1.2 gm/kg protein intake (vs <0.8 gm/kg) had a lower risk of becoming dependent the following tasks: heavy work at home; walking one-half mile; climbing stairs; stooping, kneeling, crouching; lifting >10 lbs, lifting <10 lbs. Subjects consuming ≥ 1.2 (vs <0.8) gm/kg/day of protein had a 41% lower risk of becoming dependent in ≥1 functional task over 12 years. The beneficial effect of higher protein intake was strengthened among subjects who were more active and had higher SMM. There was also evidence of a beneficial interaction of both vitamin D and calcium with physical activity and SMM. These results suggest that participation in home-based functional exercise in older post-hip fracture adults and higher intakes of dietary protein help to preserve functional capacity among community-dwelling older adults.