Physical activity across adulthood in relation to fat and lean body mass in early old age: findings from the Medical Research Council National Survey of Health and Development, 1946-2010

Abstract

Fat and lean body mass have important implications for health and physical functioning in older age, and physical activity is purported to be an important modifiable determinant. However, our evidence-based understanding of its role is limited. We examined the associations of physical activity, assessed both by self-report (using data on leisure time physical activity (LTPA) collected on 4 occasions over a 28-year period) and objectively (using 5-day heart rate and movement monitoring), with fat and lean mass at ages 60-64 years in 1,162 British participants from the Medical Research Council National Survey of Health and Development in 1946-2010. Higher objectively assessed physical activity energy expenditure (PAEE) at ages 60-64 years was associated with lower fat mass and android (abdominal):gynoid (hip) fat ratio (mean differences in fat mass per 1-standard deviation increase in PAEE were -0.79 kg/m(1.2) in men (95% confidence interval: -1.08, -0.50) and -1.79 kg/m(1.2) (95% confidence interval: -2.15, -1.42) in women). After adjustment for fat mass, higher PAEE was associated with higher appendicular lean mass. Both light and moderate-to-vigorous intensities of activity were associated with fat mass, and the latter was associated with lean mass. More frequent LTPA across adulthood was associated with lower fat mass (in women only) and higher appendicular lean mass (in both sexes, after adjustment for fat mass). These results support the promotion of LTPA across adulthood, as well as both light and moderate-to-vigorous intensities of activity among older adults.

Keywords: body fat distribution; motor activity; obesity; sarcopenia; sedentary lifestyle; skeletal muscle.

Figure 1.

Mean difference in body composition outcomes at ages 60–64 years in those who were moderately and most active (compared with inactive) at ages 36, 43, 53, and 60–64 years in the Medical Research Council National Survey of Health and Development, United Kingdom, 1946–2010. A) Fat mass index (kg/m^1.2), B) android (abdominal):gynoid (hip) fat mass ratio, C) appendicular lean mass (kg/m²), D) appendicular lean mass index (kg/m²) adjusted for fat mass index (kg/m^1.2). The point estimates show, from left to right, those who were inactive, moderately active, and most active at each age. Men, black diamonds; women, gray circles. Activity at each age was coded as inactive (no participation; reference category), moderately active (participated 1–4 times), or most active (participated ≥5 times) in the previous month (at age 36 years) or in the previous month or 4-week period (at ages 43, 53, and 60–64 years). Samples included 569 men and 642 women. P for sex interaction term < 0.1 in all age groups in A and C and in the group aged 60–64 years in D. Bars, 95% confidence intervals.