Mizoguchi Ayato, Kiyohara Katsunori, Kado Naoki, Suzuki Toshiaki
Graduate School of Health Sciences, Kansai University of Health Sciences, Kumatori, JPN.
Clinical Research Division of Rehabilitation, Sakakibarahakuho Hospital, Tsu, JPN.
Cureus. 2025 Jul 10;17(7):e87695. doi: 10.7759/cureus.87695. eCollection 2025 Jul.
Background and objective The H-reflex amplitude of certain muscles, such as the wrist and ankle, decreases immediately after performing a force control task that actively controls muscle output. However, this was unknown for the fingers. Therefore, the effect of force control exercises on the excitability of anterior horn cells of the spinal cord in the thumb was investigated using F waves. Materials and methods The participants were 15 healthy subjects. The exercise was to control the palmar abduction of the finger on the non-dominant hand side to 20% MVC (maximum voluntary contraction: MVC). In the force control task, visual information was used to actively control muscle output. In the non-force control task, participants were instructed to hold the thumb in a palmar abduction position against a constant external load, using isometric muscle contraction to maintain the posture without visual feedback or force modulation. Each task was practiced 10 times for 90 seconds, and the F wave was derived from the short abductor pollicis brevis muscle pre- and post-assignment at rest. The F/M amplitude ratio and frequency of appearance were used as analysis items; the F/M amplitude ratio was defined as the average of the vertex-to-vertex amplitudes of the 30 F waves obtained in one stimulus divided by the maximum amplitude value of the M wave, expressed as a percentage. Persistence was defined as the number of F waves that appeared for the number of stimuli in one trial and expressed as a percentage. Motor performance was assessed by performing controlled movements of 20% MVC of the thumb palmar abduction pre- and post-task with visual deprivation. Results In the force control task, the F/M amplitude ratio decreased post-task compared to pre-task. In the non-force control task, no differences were found between pre- and post-task. There were no differences in motor performance before and after practice for both tasks. Conclusion In the force control task, there was a decrease in the amplitude F/M ratio post-task. Furthermore, this decrease in the amplitude F/M ratio was thought to be due to active force control.
背景与目的 某些肌肉（如手腕和脚踝处的肌肉）在执行主动控制肌肉输出的力控制任务后，其Hoffmann反射（H反射）波幅会立即降低。然而，手指肌肉的情况尚不清楚。因此，本研究使用F波来探究力控制练习对拇指脊髓前角细胞兴奋性的影响。
材料与方法 研究对象为15名健康受试者。练习内容是将非优势手一侧手指的掌侧外展控制在最大自主收缩（MVC）的20%。在力控制任务中，利用视觉信息主动控制肌肉输出。在非力控制任务中，受试者被要求在恒定外部负荷下将拇指保持在掌侧外展位，通过等长肌肉收缩来维持姿势，且无视觉反馈或力的调节。每个任务练习10次，每次90秒，在休息状态下，于任务前后从拇短展肌引出F波。将F波与M波的波幅比（F/M波幅比）和出现频率作为分析指标；F/M波幅比定义为一次刺激中获得的30个F波从顶点到顶点的波幅平均值除以M波的最大波幅值，以百分比表示。持续性定义为一次试验中刺激次数内出现的F波数量，以百分比表示。通过在视觉剥夺条件下对任务前后拇指掌侧外展20%MVC的控制运动来评估运动表现。
结果 在力控制任务中，任务后F/M波幅比相较于任务前降低。在非力控制任务中，任务前后未发现差异。两项任务练习前后的运动表现均无差异。
结论 在力控制任务中，任务后F/M波幅比降低。此外，这种F/M波幅比的降低被认为是由于主动力控制所致。
