Program in Physical Therapy, Washington University School of Medicine, St. Louis, Missouri, United States.
School of Kinesiology, Auburn University, Auburn, Alabama, United States.
J Appl Physiol (1985). 2023 May 1;134(5):1240-1255. doi: 10.1152/japplphysiol.00704.2022. Epub 2023 Apr 6.
The effects of low-load resistance training with blood flow restriction (BFR) on hypertrophy of type I/II myofibers remains unclear, especially in females. The purpose of the present study is to examine changes in type I/II myofiber cross-sectional area (fCSA) and muscle CSA (mCSA) of the vastus lateralis (VL) from before (Pre) to after (Post) 6 wk of high-load resistance training (HL; = 15, 8 females) and low-load resistance training with BFR ( = 16, 8 females). Mixed-effects models were used to analyze fCSA with group (HL, BFR), sex (M, F), fiber type (I, II), and time (Pre, Post) included as factors. mCSA increased from pre- to posttraining ( < 0.001, = 0.91) and was greater in males compared with females ( < 0.001, = 2.26). Type II fCSA increased pre- to post-HL ( < 0.05, = 0.46) and was greater in males compared with females ( < 0.05, = 0.78). There were no significant increases in fCSA pre- to post-BFR for either fiber type or sex. Cohen's , however, revealed moderate effect sizes in type I and II fCSA for males ( = 0.59 and 0.67), although this did not hold true for females ( = 0.29 and 0.34). Conversely, the increase in type II fCSA was greater for females than for males after HL. In conclusion, low-load resistance training with BFR may not promote myofiber hypertrophy to the level of HL resistance training, and similar responses were generally observed for males and females. In contrast, comparable effect sizes for mCSA and 1-repetition maximum (1RM) between groups suggest that BFR could play a role in a resistance training program. This is the first study, to our knowledge, to examine myofiber hypertrophy from low-load resistance training with blood flow restriction (BFR) in females. Although this type of training did not result in myofiber hypertrophy, there were comparable increases in muscle cross-sectional area compared with high-load resistance training. These findings possibly highlight that males and females respond in a similar manner to high-load resistance training and low-load resistance training with BFR.
低负荷抗阻训练结合血流限制（BFR）对 I/II 型肌纤维肥大的影响尚不清楚，尤其是在女性中。本研究的目的是观察高负荷抗阻训练（HL；n = 15，8 名女性）和低负荷抗阻训练结合血流限制（BFR；n = 16，8 名女性）6 周后，股外侧肌（VL）I/II 型肌纤维横截面积（fCSA）和肌肉横截面积（mCSA）的变化。采用混合效应模型，以组（HL、BFR）、性别（M、F）、纤维类型（I、II）和时间（Pre、Post）为因素，分析 fCSA。mCSA 从训练前到训练后增加（<0.001，=0.91），男性高于女性（<0.001，=2.26）。II 型 fCSA 在 HL 前后增加（<0.05，=0.46），男性高于女性（<0.05，=0.78）。无论性别如何，BFR 前后两种纤维类型的 fCSA 均无明显增加。然而，Cohen's 揭示了男性 I 型和 II 型 fCSA 的中等效应大小（=0.59 和 0.67），但这并不适用于女性（=0.29 和 0.34）。相反，HL 后女性 II 型 fCSA 的增加大于男性。总之，低负荷抗阻训练结合 BFR 可能不会使肌纤维肥大达到 HL 抗阻训练的水平，且男性和女性的反应通常相似。相反，组间 mCSA 和 1 次重复最大重量（1RM）的效应大小相当，表明 BFR 可能在抗阻训练计划中发挥作用。这是我们所知的首次研究低负荷抗阻训练结合血流限制（BFR）对女性肌纤维肥大的影响。尽管这种训练方式没有导致肌纤维肥大，但与高负荷抗阻训练相比，肌肉横截面积有类似的增加。这些发现可能表明，男性和女性对高负荷抗阻训练和低负荷抗阻训练结合 BFR 的反应相似。
