Forwood M R, Parker A W
Department of Physical Education, Queensland University of Technology, Australia.
Bone Miner. 1991 Apr;13(1):35-46. doi: 10.1016/0169-6009(91)90048-5.
Twenty-four male rats, aged 12 weeks, were subjected to approximately 20,000 loading cycles per day of treadmill running (2 h/day, 26.8 m/min and 10% gradient) for 5 (group A) and 10 days (group B); with corresponding controls (C5) and (C10). Rats in groups B and C10 were given weekly doses of tetracycline from 4 days prior to training. Following training, right tibiae and femora were tested to failure in torsion at 180 degrees/s. Sections were cut from the distal, mid and proximal diaphysis of left bones, bulk-stained in basic fuchsin and two transverse sections (50 microns) were cut and examined for the presence of microdamage and fluorescence. Results for mechanical testing showed a significant reduction in stiffness of tibiae (P less than 0.01) for groups A and B and a significant increase in twist angle (P less than 0.01) for group A when compared with controls. No evidence of microdamage was observed from histological analysis. But, labelling demonstrated reduced appositional growth of the periosteal and endosteal surface at the mid-diaphysis of exercised tibiae (P less than 0.01). These tibiae also showed fewer regions of, measurable, appositional growth than controls (P less than 0.05). Exercised femora showed increased appositional growth at the endocortical surface of the mid-diaphysis (P less than 0.05). Reductions in stiffness of exercised tibiae were significantly correlated with cross-sectional area.
24只12周龄雄性大鼠，每天进行约20000次的跑步机跑步负荷循环（每天2小时，速度26.8米/分钟，坡度10%），持续5天（A组）和10天（B组）；并设置相应对照组（C5组和C10组）。B组和C10组大鼠在训练前4天开始每周给予四环素。训练后，对右侧胫骨和股骨进行扭转试验直至破坏，扭转速度为180度/秒。从左侧骨骼的远端、中段和近端骨干切取切片，用碱性品红进行整体染色，然后切取两片50微米厚的横向切片，检查微损伤和荧光情况。力学测试结果显示，与对照组相比，A组和B组胫骨的刚度显著降低（P<0.01），A组的扭转角度显著增加（P<0.01）。组织学分析未观察到微损伤迹象。但是，标记显示运动后胫骨中段骨膜和骨内膜表面的贴壁生长减少（P<0.01）。这些胫骨的可测量贴壁生长区域也比对照组少（P<0.05）。运动后的股骨在中段骨干的皮质内表面贴壁生长增加（P<0.05）。运动后胫骨刚度的降低与横截面积显著相关。
