Nadell Jason A, Shaw Colin N
Department of Anthropology, Durham University, Durham, UK.
Department of Archaeology and Anthropology, University of Cambridge, Cambridge, UK.
Am J Phys Anthropol. 2016 Mar;159(3):410-22. doi: 10.1002/ajpa.22889. Epub 2015 Nov 5.
Morphological variation along the human limb reflects complex structural trade-offs between bone strength and mass. Here we assess how varying levels of plasticity and constraint affect this structure and influence the response to habitual loading along the diaphysis.
Cross-sectional geometric properties including total area, cortical area, and rigidity were compared from the upper (humerus: 50% of length, radius: 66%, 50%, 4%) and lower (tibia: 50%, 38%, 4%) limbs of male varsity-level athletes and matched controls with distinct habitual loading histories.
Geometric properties among cricketers and swimmers were significantly greater at the humeral midshaft, mid-proximal radius, and radial midshaft compared to controls. By contrast, no significant differences were found among athletes or controls at the distal radius. The tibial midshafts of hockey players and runners also displayed greater area and rigidity compared to controls. Differences in geometry among the three groups became less pronounced distally, where structure was comparable among athletes and controls at 4% of tibial length. Additionally, coefficients of variation revealed that variation among athletes of the same sport was highest distally in both the upper and lower limb and lowest at midshaft, where structure most closely reflected the activity pattern of each loading group.
These results support previous research suggesting that distal limb sections are more tightly constrained by safety factors compared to midshafts and proximal sections. Overall, it appears that plasticity and constraint vary not only between limb segments in correspondence to known activity patterns, but also along specific sections of the diaphysis.
人类四肢的形态变化反映了骨强度和骨量之间复杂的结构权衡。在此，我们评估不同程度的可塑性和约束如何影响这种结构，并影响骨干对习惯性负荷的反应。
比较了男性大学水平运动员和匹配对照组上肢（肱骨：长度的50%，桡骨：66%、50%、4%）和下肢（胫骨：50%、38%、4%）的横截面几何特性，包括总面积、皮质面积和刚度，这些运动员和对照组具有不同的习惯性负荷历史。
与对照组相比，板球运动员和游泳运动员肱骨中段、近端桡骨中部和桡骨中段的几何特性明显更大。相比之下，桡骨远端的运动员或对照组之间未发现显著差异。曲棍球运动员和跑步者的胫骨中段与对照组相比也显示出更大的面积和刚度。三组之间的几何差异在远端变得不那么明显，在胫骨长度的4%处，运动员和对照组的结构相当。此外，变异系数显示，同一运动项目的运动员之间的变异在上下肢远端最高，在中段最低，中段结构最能反映每个负荷组的活动模式。
这些结果支持了先前的研究，表明与中段和近端相比，肢体远端部分受安全因素的约束更强。总体而言，似乎可塑性和约束不仅在肢体节段之间因应已知的活动模式而有所不同，而且在骨干的特定部分也有所不同。
