Purpose: This investigation examined the effect of 6 months of high- or low-intensity resistance exercise (REX) on bone mineral density (BMD) and biochemical markers of bone turnover in adults aged 60-83 yr.
Methods: Sixty-two men and women (68.4 +/- 6 yr) were stratified for strength and randomly assigned to a control (CON, N = 16), low-intensity (LEX, N = 24), or high-intensity (HEX, N = 22) group. Subjects participated in 6 months of progressive REX training. Subjects trained at either 50% of their one repetition maximum (1-RM) for 13 repetitions (LEX) or 80% of 1-RM for 8 repetitions (HEX) 3 times x wk(-1) for 24 wk. One set each of 12 exercises was performed. 1-RM was measured for eight exercises. BMD was measured for total body, femoral neck, and lumbar spine by dual energy x-ray absorptiometry (DXA). Serum levels of bone-specific alkaline phosphatase (BAP), osteocalcin (OC), and pyridinoline cross-links (PYD) were measured.
Results: 1-RM significantly increased for all exercises tested for both the HEX and LEX groups (P < and = 0.050). The percent increases in total strength (sum of all eight 1-RMs) were 17.2% and 17.8% for the LEX and HEX groups, respectively. Bone mineral density (BMD) of the femoral neck significantly (P < 0.05) increased by 1.96% for the HEX group. No other significant changes for BMD were found. OC increased by 25.1% and 39.0% for the LEX and HEX groups, respectively (P < 0.05). BAP significantly (P < 0.05) increased 7.1% for the HEX group.
Conclusion: These data indicate high-intensity REX training was successful for improving BMD of the femoral neck in healthy elderly subjects. Also, these data suggest REX increased bone turnover, which over time may lead to further changes in BMD.