| This
study examined the relationship of muscular strength and lean tissue
with age-related patterns in bone mineral density (BMD) in men 20-81
years of age. Subjects were assigned to one of three age groups, Young
Men (YM), (n = 25, 20-39 yrs), Middle-aged Men (MM) (n = 24, 40-59
yrs), and Older Men (OM) (n = 23, 60-81 yrs). Isotonic and isokinetic
strength was assessed for the quadriceps and hamstrings muscle groups.
DXA (Lunar DPX-IQ) was used to measure spine, hip, and total body
BMD and body composition. OM had significantly lower (p < 0.05)
total lean body mass (LBM) than MM and lower leg lean mass (LM) than
YM and MM. OM had significantly lower (p < 0.01) BMD than YM and
MM at the femoral neck and total hip sites and a higher proportion
of OM were osteopenic and osteoporotic at the total hip site. Isotonic
and isokinetic strength for both muscle groups was positively related
(p < 0.05) with the hip BMD sites (r = 0.38-.67). Leg LM also was
positively related to hip BMD (r = 0.37-.58). Multiple Regression
analyses determined that age and lean mass (LBM or leg LM) were significant
predictors (p < 0.05) of femoral neck, and total hip BMD, while
lean mass (LBM or leg LM) was a significant predictor (p < 0.05)
of BMD at the spine and trochanter sites. Isotonic and isokinetic
leg strength variables were significant predictors (p < 0.05) of
the total body, total hip and trochanter BMD. In conclusion, leg strength,
leg LM, and total LBM were significant predictors of BMD in men, independent
of age. These findings emphasize the importance of maintaining lean
body mass for the bone health of aging men.
KEY
WORDS: Lean body mass, osteopenia, osteoporosis, muscle strength,
bone density.
|
