Abstract：
OBJECTIVE: The aim of this study was to examine the effect of vibration on motor unit (MU) firing behavior and physical performance of antagonist muscles in healthy young adult males.
METHODS: Fourteen males (age = 24.3 ± 3.6 years) were included in this study. There were two conditions, one in which participants received 80 Hz vibration in the distal tendon of the hamstring for 30 s and the control condition (no vibration). High-density surface electromyography (HD-SEMG) signals and maximal voluntary contraction (MVC) of knee extensor muscles were evaluated before and after the respective conditions and recorded from the vastus lateralis muscle during submaximal ramp-up and sustained contractions at 30% MVC. Convolution blind source separation was used to decompose the HD-SEMG signals into individual MU firing behaviors.
RESULTS: In total, 739 MUs were detected (control; 360 MUs and vibration; 379 MUs), and a total of 312 matched MUs were identified across both submaximal contraction conditions (control: 150 MUs; vibration: 162 MUs). Vibration significantly increased the discharge rate (p = 0.047) and decreased the recruitment threshold before and after intervention (p = 0.001) but not in the control condition. Furthermore, the recruitment threshold is a factor that influences discharge rate. Significant correlations were observed between the recruitment threshold and both the ∆ discharge rate and the ∆ recruitment threshold under the vibration condition (p < 0.001).
CONCLUSIONS: Vibration increased in the discharge rate and decreased the recruitment threshold of the antagonist muscle. These findings suggested that vibration contributes to immediate changes in the neural control of antagonist muscles.
METHODS: Fourteen males (age = 24.3 ± 3.6 years) were included in this study. There were two conditions, one in which participants received 80 Hz vibration in the distal tendon of the hamstring for 30 s and the control condition (no vibration). High-density surface electromyography (HD-SEMG) signals and maximal voluntary contraction (MVC) of knee extensor muscles were evaluated before and after the respective conditions and recorded from the vastus lateralis muscle during submaximal ramp-up and sustained contractions at 30% MVC. Convolution blind source separation was used to decompose the HD-SEMG signals into individual MU firing behaviors.
RESULTS: In total, 739 MUs were detected (control; 360 MUs and vibration; 379 MUs), and a total of 312 matched MUs were identified across both submaximal contraction conditions (control: 150 MUs; vibration: 162 MUs). Vibration significantly increased the discharge rate (p = 0.047) and decreased the recruitment threshold before and after intervention (p = 0.001) but not in the control condition. Furthermore, the recruitment threshold is a factor that influences discharge rate. Significant correlations were observed between the recruitment threshold and both the ∆ discharge rate and the ∆ recruitment threshold under the vibration condition (p < 0.001).
CONCLUSIONS: Vibration increased in the discharge rate and decreased the recruitment threshold of the antagonist muscle. These findings suggested that vibration contributes to immediate changes in the neural control of antagonist muscles.
摘要：
目的：这项研究的目的是研究振动对健康年轻成年男性运动单位（MU）放电行为和拮抗性肌肉的物理性能的影响。
方法：本研究包括14名男性（年龄=24.3±3.6岁）。有两个条件,其中参与者在腿筋远端肌腱接受80Hz振动30s和对照条件（无振动）。在各自条件之前和之后评估了高密度表面肌电图（HD-SEMG）信号和膝关节伸肌的最大自主收缩（MVC），并在30％MVC的次最大斜升和持续收缩期间从股外侧肌记录。卷积盲源分离用于将HD-SEMG信号分解为单个MU激发行为。
结果：总计，检测到739个MU（对照；360个MU和振动；379个MU），并且在两种次最大收缩条件下识别出总共312个匹配的MU(对照:150MU;振动:162MU)。振动显着增加了出院率（p=0.047），并降低了干预前后的招募阈值（p=0.001），但在对照条件下没有。此外，招聘门槛是影响出院率的一个因素。在振动条件下，招募阈值与Δ放电率和Δ招募阈值之间存在显着相关性（p<0.001）。
结论：振动增加了拮抗剂肌肉的放电率，并降低了募集阈值。这些发现表明，振动有助于拮抗剂肌肉的神经控制立即发生变化。
方法：本研究包括14名男性（年龄=24.3±3.6岁）。有两个条件,其中参与者在腿筋远端肌腱接受80Hz振动30s和对照条件（无振动）。在各自条件之前和之后评估了高密度表面肌电图（HD-SEMG）信号和膝关节伸肌的最大自主收缩（MVC），并在30％MVC的次最大斜升和持续收缩期间从股外侧肌记录。卷积盲源分离用于将HD-SEMG信号分解为单个MU激发行为。
结果：总计，检测到739个MU（对照；360个MU和振动；379个MU），并且在两种次最大收缩条件下识别出总共312个匹配的MU(对照:150MU;振动:162MU)。振动显着增加了出院率（p=0.047），并降低了干预前后的招募阈值（p=0.001），但在对照条件下没有。此外，招聘门槛是影响出院率的一个因素。在振动条件下，招募阈值与Δ放电率和Δ招募阈值之间存在显着相关性（p<0.001）。
结论：振动增加了拮抗剂肌肉的放电率，并降低了募集阈值。这些发现表明，振动有助于拮抗剂肌肉的神经控制立即发生变化。
