To determine the effects of strength training (ST) on bone mineral density (BMD) and bone remodeling, 18 previously inactive untrained males [mean age 59 +/- 2 (SE) yr] were studied before and after 16 wk of either ST (n = 11) or no exercise (inactive controls; n = 7). Total, spinal (L2-L4), and femoral neck BMD were measured in nine training and seven 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 increased 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 in 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 spine BMD were not significantly different from those in the control group. There was no significant change in total body BMD. Osteocalcin increased by 19 +/- 6% after 12 wk of training (P < 0.05) and remained significantly 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.(ABSTRACT TRUNCATED AT 250 WORDS)

To determine whether a total body, heavy resistance, strength training (ST) program can significantly increase muscle strength and hypertrophy without muscle cell disruption and soreness in older men, 35 sedentary male subjects between the ages of 50 and 69 years of age (60 +/- 5, mean +/- SD) were studied. Twelve served as inactive controls. Muscular strength, cross-sectional muscle area, serum creatine kinase (CK) activity and perceived soreness were assessed before and after a 16 wk heavy resistance ST program. The ST program resulted in a 43% increase in muscular strength (p < 0.001), and a 7.2% increase in midthigh muscle area (153 +/- 24 vs 164 +/- 23 cm2, p < 0.001). There were no significant changes in strength or muscle area in the inactive control group. Peak serum CK levels were approximately twofold above baseline (278 +/- 175 vs 133 +/- 88 U/l, p < 0.01) 8 h after the first regular training session. At the end of training, the peak rise in CK levels was also reached 8 h after exercise, but was reduced substantially at the same absolute (p < 0.01) and relative resistance loads (p < 0.01) compared to the first training session. Muscle soreness after exercise was only occasionally reported at the beginning of training and was almost nonexistent after training. These results indicate that middle-aged and older men can safely participate in a total body strength training program, intense enough to produce substantial increases in muscle strength and hypertrophy, without promoting muscle soreness or significant muscle cell disruption.(ABSTRACT TRUNCATED AT 250 WORDS)

No abstract