Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, Michigan, USA.
Steindler Orthopedic Clinic, Iowa City, Iowa, USA.
Am J Sports Med. 2020 Nov;48(13):3245-3254. doi: 10.1177/0363546520962058. Epub 2020 Oct 14.
Blood flow restriction therapy (BFRT) has been increasingly applied to improve athletic performance and injury recovery. Validation of BFRT has lagged behind commercialization, and currently the mechanism by which this therapy acts is unknown. BFRT is one type of ischemic therapy, which involves exercising with blood flow restriction. Repetitive restriction of muscle blood flow (RRMBF) is another ischemic therapy type, which does not include exercise.
HYPOTHESIS/PURPOSE: The purpose was to develop a rat model of ischemic therapy, characterize changes to muscle contractility, and evaluate local and systemic biochemical and histologic responses of 2 ischemic therapy types. We hypothesized that ischemic therapy would improve muscle mass and strength as compared with the control group.
Controlled laboratory study.
Four groups of 10 Sprague-Dawley rats were established: control, stimulation, RRMBF, and BFRT. One hindlimb of each subject underwent 8 treatment sessions over 4 weeks. To simulate exercise, the stimulation group underwent peroneal nerve stimulation for 2 minutes. The RRMBF group used a pneumatic cuff inflated to 100 mm Hg with a 48-minute protocol. The BFRT group involved 100-mm Hg pneumatic cuff inflation and peroneal nerve stimulation for a 5-minute protocol. Four methods of evaluation were performed: in vivo contractility testing, histology, immunohistochemistry, and ELISA. Analysis of variance with post hoc Tukey test and linear mixed effects modeling were used to compare the treatment groups.
There was no difference in muscle mass among groups ( = .40) or between hindlimbs ( = .73). In vivo contractility testing showed no difference in maximum contractile force among groups ( = .64) or between hindlimbs ( = .30). On histology, myocyte cross-sectional area was not different among groups ( = .55) or between hindlimbs ( = .44). Pax7 immunohistochemistry demonstrated no difference in muscle satellite cell density among groups ( = .06) or between hindlimbs ( = .046). ELISA demonstrated the RRMBF group as eliciting elevated GH levels as compared with the other groups ( < .001).
Ischemic therapy did not induce gains in muscle mass, contractility strength, fiber cross-sectional area, or satellite cell density locally or systemically in this model, although the RRMBF group did have elevated GH levels on ELISA.
This animal model does not support ischemic therapy as a method to improve muscle mass, function, or satellite cell density.
血流限制疗法（BFRT）已越来越多地应用于提高运动表现和促进损伤恢复。BFRT 的验证落后于商业化，目前尚不清楚这种治疗方法的作用机制。BFRT 是一种缺血性治疗方法，包括在血流限制下进行运动。重复限制肌肉血流（RRMBF）是另一种缺血性治疗方法，不包括运动。
假设/目的：本研究旨在建立一种大鼠缺血性治疗模型，描述肌肉收缩力的变化，并评估两种缺血性治疗类型的局部和全身生化和组织学反应。我们假设与对照组相比，缺血性治疗会增加肌肉质量和力量。
对照实验室研究。
建立了 4 组 10 只 Sprague-Dawley 大鼠：对照组、刺激组、RRMBF 组和 BFRT 组。每组动物的一条后肢接受 4 周的 8 次治疗。为了模拟运动，刺激组进行腓总神经刺激 2 分钟。RRMBF 组采用充气至 100mmHg 的气动袖带，持续 48 分钟。BFRT 组采用充气至 100mmHg 的气动袖带和腓总神经刺激 5 分钟。采用 4 种评估方法：体内收缩性测试、组织学、免疫组织化学和 ELISA。采用方差分析和事后 Tukey 检验以及线性混合效应模型比较治疗组。
各组间（ =.40）或两后肢间（ =.73）的肌肉质量无差异。体内收缩性测试显示各组间最大收缩力无差异（ =.64）或两后肢间（ =.30）无差异。组织学上，各组间肌细胞横截面积无差异（ =.55）或两后肢间（ =.44）无差异。Pax7 免疫组织化学显示各组间肌肉卫星细胞密度无差异（ =.06）或两后肢间（ =.046）无差异。ELISA 显示 RMBF 组与其他组相比，GH 水平升高（ <.001）。
在该模型中，缺血性治疗并未在局部或全身诱导肌肉质量、收缩力强度、纤维横截面积或卫星细胞密度增加，尽管 RMBF 组的 GH 水平在 ELISA 上有所升高。
这种动物模型不支持缺血性治疗作为一种增加肌肉质量、功能或卫星细胞密度的方法。
