The effect of impact loading during adolescence on adult bone srength indices
Bilz, Kylie C.
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It has been shown that impact loading is associated with improved bone health. It has recently been suggested that impact loading during adolescence may be the most beneficial for a lifetime of improved bone strength. However, it is not known whether impact loading during adolescence will track into improved adult bone status. The purpose of the following study was to determine if impact loading during adolescence is associated with improved adult aBMD and bone geometry in 58 males and 31 females. Impact loading scores were estimated from a sports inventory questionnaire that was administered from 1971-1973 (males- 14-16 years of age; females -11-16 years of age). The loading score was obtained each year and an average of the three years was used for analyses. From 1997-1998 (subjects were 38-40 years of age), the subjects were recalled and areal BMD of the femoral neck (FN) was measured using DXA (Hologic 2000, array mode). Bone geometry was measured using the Hip Structural Analysis Program (HSA) and femoral neck cross-sectional area (CSA) and section modulus (Z) were used as the bone geometry indices. Data were analyzed using multiple linear regression then later the subjects were split into tertiles and the data was analyzed using ANOVA procedure, to test the extreme groups, and post-hoc comparisons done with Sheffe test. At follow-up there were no differences among groups in adult height, weight on physical activity scores (p>0.05). In males the high impact group had significantly greater aBMD than the moderate and low impact groups (p0.05). In females there was no association between impact loading during adolescence and adult aBMD, CSA or section modulus (p>0.05). The results support the theory that impact-loading activities at adolescence are associated with adult bone health in males. In females the results do not support this theory; however the effect of maturation and small sample size may have limited this study. Note:Pages 86, 104, 115, 117, 123, 127, 134 are missing from the original thesis.