Habitual physical activity and milk intake in the elderly

Abstract

 We investigated the relationship between milk intake, habitual physical activity, and body composition in 179 free-living healthy Japanese individuals (88 men and 91 women) aged 65-84 years. An electronic pedometer/accelerometer was attached to the subjects to measure the number of steps taken and the intensity of physical activity, which was expressed in metabolic equivalents (METs, multiples of resting metabolic rate); nutritional status and milk intake was assessed using a food frequency questionnaire. Body composition was assessed using a bioelectrical impedance analyzer, and calcaneal bone stiffness was evaluated on the basis of the osteo sono-assessment index. All subjects were divided into a low milk-intake group (<200 mL/day) and high milk-intake group (≧200 mL/day). We detected statistically significant differences (p<0.05) in year-averaged step count, year-averaged duration of physical activity >3METs, walking velocity, trunk muscle mass, appendicular lean tissue index, calcaneal osteo sono-assessment index, and serum albumin concentration between the low and high milk-intake groups. In particular, a correlation was found between milk intake and appendicular lean tissue index in the male subjects, and between milk intake and bone intensity in the female subjects. Adjusted odds ratios for the estimated risk of developing sarcopenia by multivariate logistic regression analysis indicated a synergistic interaction between milk intake and physical activity. The risk was significantly higher in the low milk-intake/low physical activity group than the other three groups (high milk-intake/high physical activity, high milk-intake/low physical activity, and low milk-intake/high physical activity). The results suggested that milk intake in the elderly may be beneficial for maintaining habitual physical activity and improving body composition.