Goodworth Adam D, Barrett Cody, Rylander Jonathan, Garner Brian
University of Hartford, 200 Bloomfield Avenue, West Hartford, CT 06117, United States.
Baylor University, One Bear Place #97356, Waco, TX 76798, United States.
Hum Mov Sci. 2019 Feb;63:82-95. doi: 10.1016/j.humov.2018.11.007. Epub 2018 Nov 30.
As perturbation training is gaining popularity, it is important to better understand postural control during complex three-dimensional stimuli. One clinically relevant and commonly used three-dimensional stimulus is found in hippotherapy and simulated hippotherapy on a mechanical horse. We tested nine healthy participants on a horse simulator, measured head and trunk kinematics, and characterized data in time (root-mean-square and variability) and frequency (amplitude spectra, gains, and phases) domains. We addressed three fundamental questions: 1) What is the specificity of postural responses to the simulator? 2) Which plane of motion is associated with the most and least variability (repeatable movements across repeated stimuli and across participants)? 3) To what extent are postural responses influenced by different degrees of stability (addition of pelvis straps and trunk support)? We found head and trunk responses were highly specific to the three-dimensional simulator perturbation direction and frequency. Frontal plane responses had the least variability across repetitions and participants whereas transverse motion was most variable. Head motion was more variable than the trunk at low frequencies and exhibited a marked decrease in tilt in the sagittal plane. Finally, the inclusion of pelvis straps had minimal effect on kinematics at low frequencies but altered higher frequencies; whereas added trunk support reduced head and trunk responses to perturbations and altered timing characteristics in all three planes. In conclusion, the present study suggests that frontal plane motion was under a high level of control, and results support the idea that specific head and trunk postural responses can be elicited from a complex three-dimensional stimuli, such as those found in hippotherapy. Researchers and clinicians can use results from this study to help interpret variability, implement mechanical adjustments to stability, and assess responses in pathological populations.
随着扰动训练越来越受欢迎，更好地理解复杂三维刺激下的姿势控制变得很重要。一种与临床相关且常用的三维刺激见于马术疗法以及在机械马上进行的模拟马术疗法。我们在马匹模拟器上测试了九名健康参与者，测量了头部和躯干的运动学，并在时间（均方根和变异性）和频率（振幅谱、增益和相位）域对数据进行了表征。我们探讨了三个基本问题：1）对模拟器的姿势反应有何特异性？2）哪个运动平面的变异性最大和最小（在重复刺激和不同参与者之间的可重复运动）？3）姿势反应在多大程度上受到不同程度稳定性（添加骨盆带和躯干支撑）的影响？我们发现头部和躯干反应对三维模拟器的扰动方向和频率具有高度特异性。额平面反应在重复和参与者之间的变异性最小，而横向运动的变异性最大。在低频时，头部运动比躯干更具变异性，并且在矢状面的倾斜度明显降低。最后，添加骨盆带在低频时对运动学的影响最小，但改变了较高频率；而增加躯干支撑减少了头部和躯干对扰动的反应，并改变了所有三个平面的时间特征。总之，本研究表明额平面运动受到高度控制，结果支持这样的观点，即可以从复杂的三维刺激（如马术疗法中发现的刺激）中引发特定的头部和躯干姿势反应。研究人员和临床医生可以利用本研究的结果来帮助解释变异性、对稳定性进行机械调整以及评估病理人群的反应。
