Kaastad T S, Nordsletten L, Narum S, Madsen J E, Haug E, Reikerås O
Institute for Surgical Research, Rikshospitalet The National Hospital, Oslo, Norway.
Acta Orthop Scand. 1996 Aug;67(4):371-6. doi: 10.3109/17453679609002334.
The effect of high-intensity training on the in vivo lower leg fracture strength during muscle contraction was investigated in osteoporotic rats. 20 Wistar rats were ovariectomized and given a low calcium (0.01%) diet. 7 weeks after ovariectomy they were randomized into training (T) and sedentary (S). The S group was kept cage-confined without any intervention. The T group ran on a treadmill with 10 degrees inclination 5/7 days for 8 weeks. A maximum intensity of 27 m/min was reached after 4 weeks. After 8 weeks, the right lower legs of the anesthetized animals were loaded in three-point ventral bending until fracture occurred during electrically-induced muscle contraction. The left tibiae were excised and fractured at the same level as the right tibiae. Weight gain was equal in the two groups. Energy absorption and deflection at fracture were significantly higher in the T group than in the S group in vivo during muscle contraction. In vitro, there were no significant differences in mechanical results. The mediolateral outer diameter was larger in the T group, and the maximal stress that the tibia could withstand was lower than in the S group. We conclude that 8 weeks of high-intensity training of osteoporotic rats increased the structural lower leg strength during muscle contraction. The reduced maximal stress in the training animals indicates a reduction in bone material quality. The increase of in vivo structural strength must reflect an increased protective effect of muscle contraction due to training.
在骨质疏松大鼠中研究了高强度训练对肌肉收缩期间体内小腿骨折强度的影响。20只Wistar大鼠接受卵巢切除术并给予低钙（0.01%）饮食。卵巢切除术后7周，将它们随机分为训练组（T）和久坐组（S）。S组关在笼中不进行任何干预。T组在倾斜10度的跑步机上跑步，每周5/7天，持续8周。4周后达到最大强度27米/分钟。8周后，对麻醉动物的右小腿进行三点腹侧弯曲加载，直至在电诱导肌肉收缩期间发生骨折。切除左胫骨并在与右胫骨相同水平处造成骨折。两组体重增加相同。在肌肉收缩期间，T组体内骨折时的能量吸收和挠度显著高于S组。在体外，力学结果无显著差异。T组的内外侧外径较大，胫骨能承受的最大应力低于S组。我们得出结论，对骨质疏松大鼠进行8周的高强度训练可增加肌肉收缩期间小腿的结构强度。训练动物最大应力的降低表明骨材料质量下降。体内结构强度的增加一定反映了训练导致肌肉收缩的保护作用增强。
