Influence of overall habitual physical activity on the age-related change in muscle mass in 60 to 85 year-olds.

摘要

The primary objective was to evaluate the influence of overall habitual physical activity (OHPA), including occupational (OPA), household (HPA) and leisure-time activity (LTA), on the age-related change in muscle mass. A second objective was to examine the relationship between leg muscle mass and concentric/eccentric peak force production (CEPFP) of the quadriceps femoris muscle group. The final objective was to examine the relationship between muscle mass and measures of physical function, i.e., speed of gait, speed of ascending and descending stairs, and balance. The 36 men and 46 women (initial mean age 65.6 +/- 6.9 years, weight 71.3 +/- 12.5 kg, height 168 +/- 10.1 cm.) were tested twice 7 years apart. Dual energy x-ray absorptiometry showed reductions (p 0.05) in appendicular skeletal muscle (ASM) mass by 1.9%, mineral-free lean mass by 1.6%, fat-free mass by 1.8%, bone mineral density by 5.3% and bone mineral content by 5.8%. Percent body fat increased by 8.9% (relative change) and total fat by 12.5%. Height decreased ( p 0.05). Weight and body mass index increased (p 0.05). OHPA, LTA and OPA decreased, whereas HPA remained the same as estimated from questionnaires. Change in ASM mass was not associated with OHPA, LTA, OPA, HPA, heavy, moderate, and light intensity leisure-time activity, weight training, swimming, health club and home exercise and transportation to work. Higher levels of stair climbing at work (SCW) and running during leisure (RDL) were associated with a smaller age-related loss in ASM mass, even when accounting for age, time of follow-up and gender. Leg muscle mass was positively associated with CEPFP, even when accounting for age and gender. Age accounted for an additional amount of the variance in CEPFP indicating that declines in strength are not caused uniquely by loss in muscle mass. Gender did not have an association with CEPFP. ASM mass was not associated with speed of ascending and descending stairs and speed of gait. Greater amounts of ASM mass were associated with higher balance scores, even when accounting for age, weight and gender. In summary, only two of the examined physical activity estimates, SCW and RDL, were associated with change in ASM mass.