Patterns and correlates of muscle strength loss in older women.
BACKGROUND
The aging process is associated with progressive declines in muscle strength, resulting in functional disability and reduced quality of life.


OBJECTIVE
The purpose of this epidemiological study was to examine the age-related loss of grip strength both cross-sectionally and longitudinally and the risk factors associated with the decline in muscle strength in a large population of community-living older women (aged 65-91 years).


METHODS
Clinical visits, including physical examinations and lifestyle assessment, were conducted at baseline and biennially afterwards for a total of 10 years of follow-up. The upper-body muscle strength was measured by grip strength using a hand-held dynamometer.


RESULTS
The muscle strength decreased cross-sectionally (n = 9,372) as well as longitudinally (n = 5,214), as age increased, and the decline in muscle strength measured during follow-up was greater than that measured cross-sectionally at baseline. The average loss of grip strength during 10 years of follow-up was 5.1 kg, equivalent to a rate of 2.4% decline per year, with the greatest loss seen in the oldest age group (80 years or older). Cross-sectional analysis revealed that the correlates of lower muscle strength included older age, greater weight, greater height loss since age 25 years, lower protein intake, difficulties in functional tasks, and lower physical activity. In longitudinal analysis, older age, baseline strength, weight and height loss during follow-up, difficulties in functional tasks, and lower physical activity were found to be significantly and independently associated with greater loss in grip strength during follow-up.


CONCLUSIONS
Cross-sectional and longitudinal analyses of age-related loss of muscle strength yielded different rates of decline. In addition to older age and difficulties in functional tasks, a number of modifiable factors, including weight and physical activity, are associated with increased decline in muscle strength among older women.
Forrest
Kimberly Y Z
KY
Department of Health and Safety, Slippery Rock University of Pennsylvania, Slippery Rock, PA 16057, USA. kimberly.forrest@sru.edu
Zmuda
Joseph M
JM
Cauley
Jane A
JA
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008019:Life Style; D053580:Muscle Strength / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000502:physiology*; D011159:Population Surveillance; D018570:Risk Assessment; D012307:Risk Factors; D014481:United States