Sjöström M, Fridén J, Ekblom B
Acta Physiol Scand. 1987 Jul;130(3):513-20. doi: 10.1111/j.1748-1716.1987.tb08170.x.
Biopsies of m. vastus lateralis of a well-trained 46-year-old man were analysed before and after an extremely long distance run (3529 km in 7 weeks). After the period of running, both a decrease of fibre size and a neuromuscular pathology were found. Muscle fibre degeneration and regeneration, especially of type 2 (fast-twitch) fibres, was seen as well as signs of damage to the peripheral nerves. The relative amount of type 1 (slow-twitch) fibres was higher after the run. The relationships between light and electron microscopical characteristics normally present could not be found in the specimens of this man. The changes in fibre size as well as the other microscopical characteristics may express an adaptation through more or less complete fibre transformation. However, we could not rule out that a selective elimination of fibres also contributed to the observed changes. In that case, the underlying pathophysiology might have been a peripheral arterial insufficiency which was related to the extreme functional demands. These disturbances may have affected type 2 fibres more than type 1 fibres. Endurance may, on this basis, express an adaptation of the muscle through elimination of weak fibres, that is, fibres related to limited functional capacities.
对一名训练有素的46岁男性的股外侧肌进行活检，分别在超长距离跑步（7周内跑了3529公里）前后进行分析。在跑步期过后，发现肌纤维尺寸减小且存在神经肌肉病变。观察到肌肉纤维变性和再生，尤其是2型（快肌）纤维，以及周围神经损伤的迹象。跑步后1型（慢肌）纤维的相对数量更高。在该男子的样本中未发现通常存在的光镜和电镜特征之间的关系。纤维尺寸的变化以及其他显微镜特征可能通过或多或少完全的纤维转化来体现适应性。然而，我们不能排除纤维的选择性消除也导致了观察到的变化。在这种情况下，潜在的病理生理学可能是与极端功能需求相关的外周动脉供血不足。这些紊乱可能对2型纤维的影响比对1型纤维的影响更大。基于此，耐力可能通过消除弱纤维，即与有限功能能力相关的纤维，来体现肌肉的适应性。
