METHODS: Twenty-eight healthy participants were randomly assigned to the high-load blood flow restriction (BFR-HL, n = 14) and low-load blood flow restriction (BFR-LL, n = 14) groups. They underwent 3 weeks of BFR training for isometric wrist extension at intensities of 25% or 75% of maximal voluntary contraction (MVC) with matched training volume. Pre- and post-tests included MVC and trapezoidal force-tracking tests (0-75%-0% MVC) with multi-channel surface electromyography (EMG) from the extensor digitorum.
RESULTS: The BFR-HL group exhibited a greater strength gain than that of the BFR-LL group after training (BFR_HL: 26.96 ± 16.33% vs. BFR_LL: 11.16 ± 15.34%)(p = 0.020). However, only the BFR-LL group showed improvement in force steadiness for tracking performance in the post-test (p = 0.004), indicated by a smaller normalized change in force fluctuations compared to the BFR-HL group (p = 0.048). After training, the BFR-HL group activated motor units (MUs) with higher recruitment thresholds (p < 0.001) and longer inter-spike intervals (p = 0.002), contrary to the BFR-LL group, who activated MUs with lower recruitment thresholds (p < 0.001) and shorter inter-spike intervals (p < 0.001) during force-tracking. The discharge variability (p < 0.003) and common drive index (p < 0.002) of MUs were consistently reduced with training for the two groups.
CONCLUSIONS: BFR-HL training led to greater strength gains, while BFR-LL training better improved force precision control due to activation of MUs with lower recruitment thresholds and higher discharge rates.
方法:将28名健康参与者随机分配到高负荷血流限制(BFR-HL,n=14)和低负荷血流限制(BFR-LL,n=14)组。他们接受了为期3周的BFR训练,以最大自愿收缩(MVC)的25%或75%的强度进行等距腕部伸展,并具有匹配的训练量。前后测试包括MVC和梯形力跟踪测试(0-75%-0%MVC)以及来自指伸肌的多通道表面肌电图(EMG)。
结果:训练后,BFR-HL组比BFR-LL组表现出更大的力量增长(BFR_HL:26.96±16.33%vs.BFR_LL:11.16±15.34%)(p=0.020)。然而,只有BFR-LL组在后验跟踪性能的力稳定性方面有所改善(p=0.004),与BFR-HL组相比,力波动的归一化变化较小(p=0.048)。培训后,BFR-HL组激活的运动单位(MU)具有较高的募集阈值(p<0.001)和较长的尖峰间隔(p=0.002),与BFR-LL组相反,在力跟踪过程中,激活的MU具有较低的募集阈值(p<0.001)和较短的尖峰间隔(p<0.001)。两组训练后,MU的出院变异性(p<0.003)和共同驱动指数(p<0.002)均持续降低。
结论:BFR-HL训练导致更大的力量增益,而BFR-LL训练更好地改善了力的精度控制,这是由于激活了具有较低的募集阈值和较高的出院率的MU。