Oliveira João Henriques, Sá Gomes João, Bauer Philipp, Pezarat-Correia Pedro, Vaz João Rocha
Neuromuscular Research Laboratory, Faculty of Human Kinetics, University of Lisbon, Lisbon, Portugal.
CIPER, Faculty of Human Kinetics, University of Lisbon, Lisbon, Portugal.
J Mot Behav. 2025;57(3):269-277. doi: 10.1080/00222895.2025.2469725. Epub 2025 Mar 5.
The literature that investigated the influence of visual feedback properties on the magnitude and temporal structure of variability suggests that increases in the precision of visual information of the torque output (through manipulation of visual gain and its intermittency) lead the neuromuscular system to produce torque in a more steady and complex manner. However, less is known about the influence of the nature of visual feedback on torque variability. The present study aimed to investigate the effect of two different feedback natures, one from the angular position and the other from the torque produced, on the magnitude and temporal structure of torque variability during submaximal hold isometric tasks. Twenty healthy and young participants performed a knee extension isometric task, consisting in sustaining an applied resistance equivalent to 40% of their Maximal Voluntary Isometric Contraction for 30 s with visual feedback from angular position (H) and with visual feedback from torque (H). The magnitude of torque variability was calculated through the coefficient of variation. Sample Entropy was used to analyze the temporal structure of torque fluctuations, i.e., torque complexity. We observed no significant differences between conditions (H vs H) in both magnitude ( = 0.117) and the temporal structure of torque fluctuations ( = 0.940). Our results demonstrated that torque regulation seems not to be affected by the nature of the visual feedback during hold submaximal isometric tasks, suggesting a participation of sensorimotor system due to the nature of the task. Researchers should take this into account to take methodological decisions when using hold submaximal isometric tasks to investigate possible changes in motor control.
调查视觉反馈特性对变异性大小和时间结构影响的文献表明，扭矩输出视觉信息精度的提高（通过视觉增益及其间歇性的操纵）会使神经肌肉系统以更稳定和复杂的方式产生扭矩。然而，关于视觉反馈性质对扭矩变异性的影响，人们了解得较少。本研究旨在调查两种不同反馈性质（一种来自角位置，另一种来自产生的扭矩）对次最大等长收缩任务期间扭矩变异性大小和时间结构的影响。20名健康的年轻参与者进行了膝关节伸展等长任务，包括在有来自角位置的视觉反馈（H）和有来自扭矩的视觉反馈（H）的情况下，以相当于其最大随意等长收缩40%的施加阻力持续30秒。通过变异系数计算扭矩变异性的大小。样本熵用于分析扭矩波动的时间结构，即扭矩复杂性。我们观察到在两种条件（H与H）之间，在大小（=0.117）和扭矩波动的时间结构（=0.940）方面均无显著差异。我们的结果表明，在次最大等长收缩任务期间，扭矩调节似乎不受视觉反馈性质的影响，这表明由于任务的性质，感觉运动系统参与其中。研究人员在使用次最大等长收缩任务来研究运动控制的可能变化时，在做出方法学决策时应考虑到这一点。
