Date Published: October 1, 2011
Publisher: Elsevier Science
Author(s): Rachel Cooper, Gita D. Mishra, Diana Kuh.
Evidence, mainly from cross-sectional studies, suggests that physical activity is a potentially important modifiable factor associated with physical performance and strength in older age. It is unclear whether the benefits of physical activity accumulate across life or whether there are sensitive periods when physical activity is more influential.
To examine the associations of leisure-time physical activity across adulthood with physical performance and strength in midlife, and to test whether there are cumulative benefits of physical activity.
Using data on approximately 2400 men and women from the UK Medical Research Council National Survey of Health and Development, followed up since birth in March 1946, the associations of physical activity levels during leisure time self-reported prospectively at ages 36, 43, and 53 years with grip strength, standing balance, and chair rise times, assessed by nurses at age 53 years (in 1999), were examined in 2010.
There were independent positive effects of physical activity at all three ages on chair rise performance, and at ages 43 and 53 years on standing balance performance, even after adjusting for covariates. These results were supported by evidence of cumulative effects found when using structured life course models. Physical activity and grip strength were not associated in women and, in men, only physical activity at age 53 years was associated with grip strength.
There are cumulative benefits of physical activity across adulthood on physical performance in midlife. Increased activity should be promoted early in adulthood to ensure the maintenance of physical performance in later life.
Maintaining physical performance and muscle strength with age is important given that lower levels in older populations are associated with increased risk of subsequent health problems, loss of independence, and shorter survival times.1–3 As the global population ages, there is a growing need to identify modifiable factors across life that influence physical performance and strength in later life. Such factors may influence the peak achieved in earlier life or the timing and rate of subsequent decline.4,5 It is therefore necessary to elucidate whether the effects of these factors accumulate across life or are more influential during sensitive periods when intervention to maintain or improve performance and strength is likely to be most beneficial.
The Medical Research Council National Survey of Health and Development (NSHD) is a socially stratified sample of all births that occurred during 1 week in March 1946 across England, Scotland, and Wales. This cohort of 5362 men and women has been followed up prospectively over 20 times across life from birth onwards. In 1999, when study participants were aged 53 years, 3035 were contacted successfully, of whom 2984 received a home visit from a nurse and 2956 successfully completed at least one of the physical performance or strength tests. Of those 2327 participants not successfully contacted in 1999, a total of 469 had died (8.7% of the original cohort); 948 had refused to participate (17.7%); 580 were abroad (10.8%); and 330 could not be traced (6.2%).19 The survey collects data on many aspects of health and lifestyle, including physical activity. The data collection in 1999 received ethical approval from the UK Multicentre Research Ethics Committee (MREC), and informed consent was given by participants to each set of questions and measures undertaken.
Men were stronger, had better physical performance levels at age 53 years, and were more likely to be active at ages 36 and 43 years than women (Table 1). Physical activity levels at each age were strongly associated with levels at the other two ages (p<0.01 from chi-square tests). Eighteen percent of the study participants were inactive, and 10% were most active at all three ages. In a nationally representative British population, evidence was found of cumulative benefits of physical activity across adulthood for physical performance in midlife. These associations were robust to adjustment for a range of potential confounding factors. There was also evidence to suggest that higher current physical activity levels were associated with stronger grip strength in men. Increased activity should be promoted early in adulthood to ensure the maintenance of physical performance in later life. When promoting physical activity, it may be necessary to encourage people to participate in specific types of activity in order for a beneficial effect on upper body strength to be seen. Source: http://doi.org/10.1016/j.amepre.2011.06.035