Site-Specific Effects of Strength Training on Bone Structure and Geometry of Ultradistal Radius in Postmenopausal Women

Abstract

Knowledge of the effects of exercise on bone mass in postmenopausal women is limited and controversial. Animal studies have shown that the response of bone to bending strain is an alteration of bone geometry. We studied 250 postmenopausal women, aged 52-72 years, willing to participate in a 6-month exercise program. The first 125 started the program immediately and the remaining 125 served as controls. The training program included exercises designed to maximize the stress on the wrist. One hundred and eighteen of the active group and 116 of the control group completed the study and were reassessed 6 months later. Bone mineral density (BMD) of the femoral neck, lumbar spine, ultradistal and proximal radius was measured by dual-energy X-ray absorptiometry (DXA) both before and at the end of the exercise program. The forearm was also evaluated by peripheral quantitative computed tomography, which measures the area, bone mineral content (BMC), and volumetric density for both the cortical and the trabecular component. The results showed that the DXA measurements at the femoral neck, lumbar spine, ultradistal and proximal radius were similar between the two groups. No significant difference was detected after the exercise program at the proximal radius. At the ultradistal radius, the crosssectional area of cortical bone rose by 2.8 ± 15.0% (SD, p < 0.05), apparently for both periosteal apposition and corticalization of the trabecular tissue. The volumetric density of cortical bone rose by 2.2 ± 15.8% (p < 0.1), and that of trabecular bone decreased by 2.6 ± 10.7% (p < 0.01). The combined changes in both bone volume and density in the exercise group were associated with marked increase in cortical BMC (3.1 ± 10.7%, p < 0.01) and decrease in trabecular BMC (−3.4 ± 14.2%, p < 0.05), which were statistically different from those observed in the control group (p < 0.05). In conclusion, these results confirm that site-specific moderate physical exercises have very little effect on bone mass. However, it appears that some exercises may reshape the bone segment under stress by increasing both the cross-sectional area and the density of the cortical component. These structural changes are theoretically associated with increases in the bending strength. (J Bone Miner Res 1999;14:120-124)

Effects of a 20-week high-intensity strength and sprint training program on tibial bone structure and strength in middle-aged and older male sprint athletes: a randomized controlled trial

“…Parallel results have also been observed in some intervention studies on premenopausal [31] and postmenopausal [28,32,33] women after six to twelve months' strength and/or impact training. Interventions targeting bone structure among older people are, however, scarce and comparison of the results is challenging due to variation in study populations, training programs, intervention duration and the bone sites measured.…”

“…The adaptation in this exercise training program, as in some previous studies [28][29][30], occurred in bone structure and, theoretically, in bending strength without increases in BMD.…”

Muscle strength is a determinant of bone mineral content in the hemiparetic upper extremity: Implications for stroke rehabilitation

“…For example, Kerr et al [52] found in postmenopausal women that BMD at the ultradistal radial site was increased following a 1-year strength training program. A 6-month strengthening program designed to maximize the stress on the wrist also increased the cortical BMC at ultradistal radius in postmenopausal women [53].…”

Exercise-induced bone gain is due to enlargement in bone size without a change in volumetric bone density: a peripheral quantitative computed tomography study of the upper arms of male tennis players

“…A redistribution of the mineral of a bone without changes in the total amount of bone mineral or bone's outer geometry, has also been shown to be possible. 1,8 Earlier studies of tennis players 10,22,31 suggested that the outer dimensions of the playing-arm bones are larger than those of their nonactive counterparts. In addition, in the CT study by Dalen et al, 10 the marrow cavity area of the humeral shaft of seven professional tennis players was examined.…”