Bauer Philipp, Gomes João S, Oliveira João H, Santos Paulo, Pezarat-Correia Pedro, Vaz João R
Egas Moniz Center for Interdisciplinary Research (CiiEM), Egas Moniz School of Health & Science, Caparica, Almada, Portugal.
Neuromuscular Research Laboratory, Faculty of Human Kinetics, University of Lisbon, Cruz-Quebrada, Lisbon, Portugal.
PLoS One. 2025 Jun 25;20(6):e0325302. doi: 10.1371/journal.pone.0325302. eCollection 2025.
Recent scientific evidence suggests that an external focus of attention (vs. an internal focus of attention) promotes a greater number of motor solutions, rendering the system more adaptable and complex. Therefore, the present study investigated the effect of the attentional focus (external vs. internal) on torque complexity and variability as well as its associated intermuscular coordination processes. Fourteen participants performed maximal and submaximal isometric knee extension tasks in three conditions (control, external focus, internal focus) to assess immediate effects of the focus of attention in a within-subjects comparison. Peak torque was extracted from maximal trials. Regarding submaximal trials, torque complexity and the magnitude of variability were assessed through Sample Entropy (SampEn), i.e., a measure of regularity in the temporal structure of torque output and coefficient of variation (CV), respectively. The intermuscular coordination was assessed through co-contraction index. An external focus led to an increase in SampEn (i.e., decreased regularity) when compared to an internal focus (p = 0.032) and a control condition (p = 0.036). Conversely, no differences were found for CV and peak torque. The external focus promoted a decrease in muscular activity of vastus medialis in comparison with the internal focus (p = 0.040) and an increase in muscular activity when compared to the control condition (p < 0.001). Furthermore, an external focus led to decreased muscular activity of semitendinosus as well as a decrease in the co-contraction indices involving semitendinosus in comparison with the internal focus and the control condition (all p < 0.05). The present findings suggest that an external focus leads to an enhanced flexibility of motor control. Moreover, the general decrease in co-contraction and in muscular activity without affecting maximal force parameters that we observed with an external focus suggest a higher efficiency of the motor system caused by intermuscular coordination processes.
最近的科学证据表明，注意力的外部焦点（相对于内部焦点）能促进更多的运动解决方案，使系统更具适应性和复杂性。因此，本研究调查了注意力焦点（外部与内部）对扭矩复杂性和变异性及其相关的肌肉间协调过程的影响。14名参与者在三种条件下（对照、外部焦点、内部焦点）进行了最大和次最大等长膝关节伸展任务，以在受试者内比较中评估注意力焦点的即时效应。从最大试验中提取峰值扭矩。对于次最大试验，分别通过样本熵（SampEn）（即扭矩输出时间结构的规律性度量）和变异系数（CV）评估扭矩复杂性和变异性大小。通过共同收缩指数评估肌肉间协调。与内部焦点（p = 0.032）和对照条件（p = 0.036）相比，外部焦点导致SampEn增加（即规律性降低）。相反，CV和峰值扭矩未发现差异。与内部焦点相比，外部焦点促进股内侧肌肌肉活动减少（p = 0.040），与对照条件相比则增加（p < 0.001）。此外，与内部焦点和对照条件相比，外部焦点导致半腱肌肌肉活动减少以及涉及半腱肌的共同收缩指数降低（所有p < 0.05）。本研究结果表明，外部焦点导致运动控制的灵活性增强。此外，我们观察到外部焦点导致共同收缩和肌肉活动普遍减少，而不影响最大力量参数，这表明肌肉间协调过程导致运动系统效率更高。
