A. Menkes et al., STRENGTH TRAINING INCREASES REGIONAL BONE-MINERAL DENSITY AND BONE REMODELING IN MIDDLE-AGED AND OLDER MEN, Journal of applied physiology, 74(5), 1993, pp. 2478-2484
To determine the effects of strength training (ST) on bone mineral den
sity (BMD) and bone remodeling, 18 previously inactive untrained males
[mean age 59 +/- 2 (SE) yr] were studied before and after 16 wk of ei
ther ST (n = 11) or no exercise (inactive controls; n = 7). Total, spi
nal (L2-L4), and femoral neck BMD were measured in nine training and s
even control subjects before and after the experimental period. Serum
concentrations of osteocalcin, skeletal alkaline phosphatase isoenzyme
, and tartrate-resistant acid phosphatase were measured before, during
, and after the experimental program in all subjects. Training increas
ed muscular strength by an average of 45 +/- 3% (P < 0.001) on a three
-repetition maximum test and by 32 +/- 4% (P < 0.001) on an isokinetic
test of the knee extensors performed at 60-degrees/s. BMD increased i
n the femoral neck by 3.8 +/- 1.0% (0.900 +/- 0.05 vs. 0.933 +/- 0.05
g/cm2, P < 0.05) and in the lumbar spine by 2.0 +/- 0.9% (1.180 +/- 0.
06 vs. 1.203 +/- 0.06 g/cm2, P < 0.05). However, changes in lumbar spi
ne BMD were not significantly different from those in the control grou
p. There was no significant change in total body BMD. Osteocalcin incr
eased by 19 +/- 6% after 12 wk of training (P < 0.05) and remained sig
nificantly elevated after 16 wk of training (P < 0.05). There was a 26
+/- 11% increase in skeletal alkaline phosphatase isoenzyme levels (P
< 0.05) after 16 wk of training. There were no significant difference
s in tartrate-resistant acid phosphatase levels. There were no signifi
cant changes in muscular strength, BMD, or any of the serum markers in
the control group. These findings confirm that 16 wk of ST in middle-
aged and older men results in increased regional BMD. These increases
may be mediated by an increase in bone formation.