Adjei Ermyntrude, Nalam Varun, Lee Hyunglae
School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, United States.
School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, United States.
Front Sports Act Living. 2020 Oct 9;2:570449. doi: 10.3389/fspor.2020.570449. eCollection 2020.
The purpose of this study is to quantify sex differences in 2-dimensional (2D) ankle stiffness during upright standing balance and investigate the mechanisms for the differences. A dual-axis robotic platform, capable of perturbing the ankle and measuring the corresponding ankle torques in both the sagittal and frontal planes, was used to reliably quantify the 2D ankle stiffness while healthy young human subjects perform a range of standing balance tasks, specifically, ankle muscle co-contraction tasks, weight-bearing tasks, and ankle torque generation tasks. In all task conditions and in both planes of ankle motion, ankle stiffness in males was consistently greater than that in females. Among all 26 experimental conditions, all but 2 conditions in the frontal plane showed statistically significant sex differences. Further investigation on the normalized ankle stiffness, scaled by weight times height, suggests that while sex differences in ankle stiffness in the sagittal plane could be explained by sex differences in anthropometric factors as well as neuromuscular factors, the differences in the frontal plane are mostly explained by anthropometric factors. This study also demonstrates that the sex differences in the sagittal plane were significantly higher as compared to those in the frontal plane. The results in this study will provide a foundation for not only characterizing sex differences in ankle stiffness during locomotion, but also investigating sex differences in lower body stability and risk of ankle injury.
本研究的目的是量化直立站立平衡期间二维（2D）踝关节僵硬度的性别差异，并探究这些差异的机制。使用一个双轴机器人平台，该平台能够扰动踝关节并测量矢状面和额状面相应的踝关节扭矩，在健康年轻受试者执行一系列站立平衡任务时，具体为踝关节肌肉共同收缩任务、负重任务和踝关节扭矩产生任务时，可靠地量化二维踝关节僵硬度。在所有任务条件下以及踝关节运动的两个平面中，男性的踝关节僵硬度始终大于女性。在所有26种实验条件中，除了额状面的2种条件外，其余所有条件均显示出统计学上显著的性别差异。对按体重乘以身高缩放的归一化踝关节僵硬度的进一步研究表明，矢状面踝关节僵硬度的性别差异可由人体测量学因素以及神经肌肉因素的性别差异来解释，而额状面的差异主要由人体测量学因素来解释。本研究还表明，矢状面的性别差异明显高于额状面。本研究结果不仅将为表征运动过程中踝关节僵硬度的性别差异提供基础，还将为研究下肢稳定性的性别差异和踝关节损伤风险提供基础。
