Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, DENMARK.
Technical University of Munich, Germany. Sylvia Lawry Centre for Multiple Sclerosis Research, Munich, GERMANY.
Med Sci Sports Exerc. 2021 Sep 1;53(9):1797-1806. doi: 10.1249/MSS.0000000000002665.
Skeletal muscle vascularization is important for tissue regeneration after injury and immobilization. We examined whether complete immobilization influences capillarization and oxygen delivery to the muscle and assessed the efficacy of rehabilitation by aerobic exercise training.
Young healthy males had one leg immobilized for 14 d and subsequently completed 4 wk of intense aerobic exercise training. Biopsies were obtained from musculus vastus lateralis, and arteriovenous blood sampling for assessment of oxygen extraction and leg blood flow during exercise was done before and after immobilization and training. Muscle capillarization, muscle and platelet content of vascular endothelial growth factor (VEGF), and muscle thrombospondin-1 were determined.
Immobilization did not have a significant impact on capillary per fiber ratio or capillary density. The content of VEGF protein in muscle samples was reduced by 36% (P = 0.024), and VEGF to thrombospondin-1 ratio was 94% lower (P = 0.046). The subsequent 4-wk training period increased the muscle VEGF content and normalized the muscle VEGF to thrombospondin-1 ratio but did not influence capillarization. Platelet VEGF content followed the trend of muscle VEGF. At the functional level, oxygen extraction, blood flow, and oxygen delivery at rest and during submaximal exercise were not affected by immobilization or training.
The results demonstrate that just 2 wk of leg immobilization leads to a strongly reduced angiogenic potential as evidenced by reduced muscle and platelet VEGF content and a reduced muscle VEGF to thrombospondin-1 ratio. Moreover, a subsequent period of intensive aerobic exercise training fails to increase capillarization in the previously immobilized leg, possibly because of the angiostatic condition caused by immobilization.
骨骼肌肉的血管生成对于损伤和固定后的组织再生很重要。我们研究了完全固定是否会影响肌肉的毛细血管生成和氧气输送，并评估了有氧运动训练康复的效果。
年轻健康的男性将一条腿固定 14 天，然后完成 4 周的高强度有氧运动训练。从股外侧肌获取活检，并在固定和训练前后进行动静脉血液采样，以评估运动时的氧气摄取和腿部血流量。测定肌肉毛细血管密度、肌肉和血小板中血管内皮生长因子（VEGF）的含量，以及肌肉血栓调节蛋白-1。
固定对毛细血管纤维比或毛细血管密度没有显著影响。肌肉样本中 VEGF 蛋白含量减少了 36%（P = 0.024），VEGF 与血栓调节蛋白-1 的比值降低了 94%（P = 0.046）。随后的 4 周训练期增加了肌肉 VEGF 含量，并使肌肉 VEGF 与血栓调节蛋白-1 的比值正常化，但并没有影响毛细血管密度。血小板 VEGF 含量与肌肉 VEGF 呈相同趋势。在功能水平上，固定或训练并不影响休息和次最大运动时的氧气摄取、血流量和氧气输送。
研究结果表明，仅仅 2 周的腿部固定就会导致血管生成潜力明显下降，这表现为肌肉和血小板 VEGF 含量降低，以及肌肉 VEGF 与血栓调节蛋白-1 的比值降低。此外，随后进行的高强度有氧运动训练未能增加先前固定腿的毛细血管密度，这可能是由于固定引起的血管生成抑制状态。
