Allometry theory to create a standard value for bone mineral content for menstruating adult females and examination of usefulness / 体力科学

Evidence suggests that sports activity can induce site-specific changes in bone mineral content (BMC) in athletes. Therefore, the first purpose of this study was to create a standard value for BMC (SV_BMC) that is independent of body size and physical exercise effect. The second purpose was to examine usefulness for the SV_BMC. In creating the SV_BMC, we recruited non-customer subjects who engaged in regular exercise but did not have site-specific changes to their bony structure. We studied 285 females (34.0±6.5 years) that were currently active, free from hormone treatment, and were not taking medication for any condition. Furthermore, all female subjects reported having a normal menstrual cycle. Bone area (BA), BMC and areal bone mineral density (aBMD) were measured by dual-energy X-ray absorption. Measurements of almost the complete skeleton, with the exception of the head, were taken (herein referred to as sub-total). This included scans of the entire spinal column, all 12 ribs, pelvis, full legs and arms. An allometry formula that relates BMC and BA was applied to determine the SV_BMC. To exclude the effect of body size, calculations were determined using the perpendicular distance from the data of each individual to that determined by allometry regression. Finally, the mean and standard deviation of the distance were converted into T-scores. In examination of reliability for the SV_BMC, we calculated the SV_BMC for three customer females who engaged in regular exercise. We found a significantly positive relationship between SV_BMC and weight/BMI. This correlation was weaker than the relationship between SV_BMC and BMC, as expected, or the relationship between SV_BMC and aBMD, with the exception of SV_BMC in the pelvis. In conclusion, this study suggests that SV_BMC is less affected by body size than by BMC or aBMD and the SV_BMC was provided highly useful in case study.

The effect of bench-stepping exercise training on BMD, BMC and bone metabolism in menopausal women / 体力科学

Since the effect of the submaximal aerobic exercise on bone had been controversial, the aim of this study was to elucidate the effect of the bench step (BS), that seemed to deliver higher mechanical load on bone than any other aerobic exercises, on the total bone mineral content (BMC) and the bone metabolism of menopausal women. Sixteen menopausal women (65 ± 9 years old) as the exercise group (ExG) and 28 pre-menopausal women (43 ± 3 years old) as the control group (CG) were studied. ExG carried out BS training with the exercise intensity at lactate threshold (LT) for 21 weeks. In ExG, BMC was measured by dual energy X-ray absorptiometry (DXA) at one year before the intervention (A year before), pre-intervention (Pre) and post-intervention (Post). Serum osteocalcin (OC) as the marker of bone formation and serum type I collagen cross-linked N-telopeptide (NTx) as the marker of bone absorption at Pre, 11th week of the intervention and Post. In CG, BMC was measured annually without the intervention. In ExG, OC was not changed, but NTx was significantly decreased by intervention (<i>p</i><0.05). The decreased amount of annual change in BMC between a year before and Pre (T1) was significantly higher compared to that between Pre and Post (T2) (<i>p</i><0.01) and CG (<i>p</i><0.001). There was no significant difference between T2 and CG. In conclusion, BS with LT could prevent decreasing BMC in menopausal women, and maintain the same level of BMC in pre-menopausal women by suppressing the bone absorption.