title: The effects of aging on muscle strength and functional ability of healthy Saudi Arabian males.
abstract: BACKGROUND
  Loss of muscle strength as a result of normal aging is reported to impair functional ability in various communities. The purpose of this study was to determine the age at which loss of muscle strength and functional ability begins, and to establish a preliminary baseline for the pattern of changes in muscle strength and functional ability of aging in adult healthy Saudi Arabian males.
  
  
  METHODS
  A sample of 160 healthy Saudi Arabian males aged 20-89 years participated in this study. The subjects were divided into seven age groups, each representing a decade. Maximum isometric A centAAmakeA centAA strength of bilateral quadriceps muscles were measured using a hand-held dynamometer. Functional ability tests that included stair walking, timed-up-and-go and balance tests were also performed and timed using a digital stopwatch.
  
  
  RESULTS
  Muscle strength and functional ability remained unchanged in the 20- and 30-year-old age groups. Around the age of 40, muscle strength and functional ability began to gradually decline. Muscle strength of males in their twenties was 380+/-62N and 330+/-60N in the right (RT) and left (LT) quadriceps, respectively. A decline with aging is represented by 190+/-40N and 110+/-30N in the RT and LT quadriceps muscles, respectively, by the eighth decade of life. Stair-walking, timed up-and-go and balance tests in the second decade were 4+/-1 sec, 8+/-2 sec and 130+/-20 sec, respectively, against 15+/-4 sec, 26+/-7 sec and 15+/-5 sec in the eighth decade. One-way ANOVA test showed that muscle strength and functional ability differed (P<0.01) among decades, except between the second and third decades (P<0.31). Age, muscle strength and functional ability displayed a significant relationship (P<0.001).
  
  
  CONCLUSIONS
  Loss of muscle strength and functional ability seem to begin in the fourth decade of life. The changes in muscle strength and functional ability have a significant relationship to aging. Clinically, these results may provide clinicians with a guide to the strength level of normal quadriceps and the functional ability of adult healthy Saudi Arabian males in relation to the normal aging process.
authors.affiliation: Department of Rehabilitation Sciences, Faculty of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia.
authors.forename: S S
authors.initials: SS
authors.lastname: Al-Abdulwahab