Department of Sport Science and Physical Education, Faculty of Health and Sport Sciences, University of Agder, Kristiansand, Norway.
Norwegian Olympic Federation, Oslo, Norway.
J Appl Physiol (1985). 2021 Aug 1;131(2):643-660. doi: 10.1152/japplphysiol.00115.2020. Epub 2021 May 6.
Myocellular stress with high-frequency blood flow-restricted resistance exercise (BFRRE) was investigated by measures of heat shock protein (HSP) responses, glycogen content, and inflammatory markers. Thirteen participants [age: 24 ± 2 yr (means ± SD), 9 males] completed two 5-day blocks of seven BFRRE sessions, separated by 10 days. Four sets of unilateral knee extensions to failure at 20% of one-repetition maximum (1RM) were performed. Muscle samples obtained before, 1 h after the first session in the first and second block ( and ), after three sessions (), during the "rest week," and at 3 () and 10 days postintervention () were analyzed for HSP70, αB-crystallin, glycogen [periodic acid-Schiff (PAS) staining], mRNAs, miRNAs, and CD68 (macrophages) and CD66b (neutrophils) cell numbers. αB-crystallin translocated from the cytosolic to the cytoskeletal fraction after and ( < 0.05) and immunostaining revealed larger responses in type I than in type II fibers (, 225 ± 184% vs. 92 ± 81%, respectively, = 0.001). HSP70 was increased in the cytoskeletal fraction at and , and immunostaining intensities were more elevated in type I than in type II fibers at (206 ± 84% vs. 72 ± 112%, respectively, <0.001), during the rest week (98 ± 66% vs. 42 ± 79%, < 0.001), and at (115 ± 82% vs. 28 ± 78%, = 0.003). Glycogen content was reduced in both fiber types, but most pronounced in type I, which did not recover until the rest week (-15% to 29%, ≤ 0.001). Intramuscular macrophage numbers were increased by ∼65% postintervention, but no changes were observed in muscle neutrophils. We conclude that high-frequency BFRRE with sets performed till failure stresses both fiber types, with type I fibers being most affected. BFRRE has been reported to preferentially stress type I muscle fibers, as evidenced by HSP responses. We extend these findings by showing that the HSP responses occur in both fiber types but more so in type I fibers and that they can still be induced after a short-term training period. Furthermore, the reductions in glycogen content of type I fibers after strenuous frequent BFRRE in unaccustomed subjects can be prolonged (≥5 days), probably due to microdamage.
本研究旨在通过热休克蛋白（HSP）反应、糖原含量和炎症标志物来探究高频血流限制阻力训练（BFRRE）对肌原纤维的影响。13 名参与者[年龄：24 ± 2 岁（均值 ± 标准差），9 名男性]完成了两个为期 5 天的 BFRRE 训练，每个训练之间间隔 10 天，各包含 7 次训练。每次训练均进行 20%最大重复次数（1RM）的单侧膝关节伸展至力竭，共 4 组。分别在第一次训练前、第一次和第二次训练的第一次训练后 1 小时（和）、三次训练后（）、“休息周”期间以及干预后 3 天（）和 10 天（）时，对肌肉样本进行 HSP70、αB-晶体蛋白、糖原[过碘酸-雪夫（PAS）染色]、mRNA、miRNA、CD68（巨噬细胞）和 CD66b（中性粒细胞）细胞计数分析。在 和 时，αB-晶体蛋白从胞浆转移到细胞骨架部分（ < 0.05），免疫染色显示Ⅰ型纤维的反应大于Ⅱ型纤维（分别为 225 ± 184%和 92 ± 81%， = 0.001）。HSP70 在细胞骨架部分和 时增加，Ⅰ型纤维的免疫染色强度在 时高于Ⅱ型纤维（分别为 206 ± 84%和 72 ± 112%， < 0.001），在“休息周”期间（98 ± 66%和 42 ± 79%， < 0.001）和 时（115 ± 82%和 28 ± 78%， = 0.003）更高。两种纤维类型的糖原含量均减少，但Ⅰ型纤维减少更明显，直到“休息周”才恢复（-15%至 29%， ≤ 0.001）。干预后，肌内巨噬细胞数量增加约 65%，但肌肉中性粒细胞无变化。综上所述，高频 BFRRE 训练至力竭可同时使两种纤维类型承受压力，Ⅰ型纤维受影响最大。已有研究表明，BFRRE 优先作用于Ⅰ型肌肉纤维，这一点可以从 HSP 反应中得到证实。本研究进一步发现，HSP 反应不仅发生在两种纤维类型中，而且在Ⅰ型纤维中更为明显，并且在短期训练后仍能诱导产生。此外，在不习惯高频 BFRRE 的情况下，Ⅰ型纤维在剧烈运动后的糖原含量减少可持续延长（≥5 天），可能是由于微损伤所致。
