INTRODUCTION Comparison of the neuromuscular performance of different athlete types may give insight into the in-vivo variability of these measures and their underpinning mechanisms. The study aims to compare the neuromuscular function of the plantar flexors of sprinters and physically active individuals to assess any differences in explosive force performance. METHODS Neuromuscular performance of a group of sprinters (highly trained/national level, n = 12; elite/international level, n = 2) and physically active individuals (n = 14) were assessed during involuntary, explosive, and maximum voluntary isometric plantar flexions, across different muscle-tendon unit (MTU) lengths (10° plantarflexion (PF), 0° (anatomical zero/neutral, AZ), and 10° dorsiflexion (DF)). Plantarflexion rate of torque development (RTD) was measured in three 50-ms time windows from their onset. The synchronous activation of the plantar flexor agonist muscles was calculated as the time difference between 1) the first and last muscle onset and 2) the onsets of the two gastrocnemii muscles. Muscle size and MTU stiffness were assessed using sonograms of the medial gastrocnemius and myotendinous junction. RESULTS Sprinters exhibited greater involuntary RTD across time points (0-50, 50-100 ms) and MTU lengths. Additionally, sprinters demonstrated greater early phase voluntary RTD (0-50, 50-100 ms) across MTU lengths. Sprinters also demonstrated greater late-phase RTD (100-150 ms), and relative maximal voluntary torque at the DF angle only. The sprinters demonstrated a more synchronous activation of the gastrocnemii muscles. There were no observable differences in muscle size and MTU stiffness between groups. CONCLUSIONS These findings suggest sprint-specific training could be a contributing factor toward improved explosive performance of the plantar flexors, particularly in the early phase of muscular contraction, evidenced by the greater explosive torque producing capabilities of sprinters.

中文翻译：

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短跑运动员与体育锻炼者的神经肌肉跖屈肌表现。

简介 比较不同类型运动员的神经肌肉表现可以深入了解这些测量值的体内变异性及其基础机制。该研究旨在比较短跑运动员和体力活跃者的跖屈肌的神经肌肉功能，以评估爆发力表现的差异。方法 对一组短跑运动员（训练有素/国家级，n = 12；精英/国际级，n = 2）和体力活跃者（n = 14）在不自主、爆发性和最大自主等距跖屈过程中的神经肌肉表现进行评估，跨越不同的肌肉肌腱单位 (MTU) 长度（10° 跖屈 (PF)、0°（解剖学零/中性，AZ）和 10° 背屈 (DF)）。跖屈扭矩发展率 (RTD) 在三个 50 毫秒的时间窗口内测量。足底屈肌主动肌的同步激活计算为 1) 第一个和最后一个肌肉启动和 2) 两个腓肠肌启动之间的时间差。使用腓肠肌内侧和肌腱交界处的超声图评估肌肉大小和 MTU 硬度。结果短跑运动员在时间点（0-50、50-100 毫秒）和 MTU 长度上表现出更大的非自愿 RTD。此外，短跑运动员在 MTU 长度上表现出更大的早期自愿 RTD（0-50、50-100 毫秒）。短跑运动员还表现出更大的后期 RTD（100-150 毫秒），以及仅在 DF 角度时的相对最大自愿扭矩。短跑运动员表现出腓肠肌更加同步的激活。各组之间的肌肉大小和 MTU 硬度没有明显差异。结论 这些发现表明，短跑专项训练可能是提高跖屈肌爆发力的一个因素，特别是在肌肉收缩的早期阶段，短跑运动员产生更大爆发力扭矩的能力就证明了这一点。