Johnston William, O'Reilly Martin, Coughlan Garrett F, Caulfield Brian
Insight Centre for Data Analytics, University College Dublin, Dublin, Ireland.
School of Public Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland.
Digit Biomark. 2018 Jan 9;1(2):106-117. doi: 10.1159/000485470. eCollection 2017 Oct-Dec.
The Y Balance Test (YBT) is one of the most commonly utilised clinical dynamic balance assessments. Research has demonstrated the utility of the YBT in identifying balance deficits in individuals following lower limb injury. However, quantifying dynamic balance based on reach distances alone fails to provide potentially important information related to the quality of movement control and choice of movement strategy during the reaching action. The addition of an inertial sensor to capture more detailed motion data may allow for the inexpensive, accessible quantification of dynamic balance control during the YBT reach excursions. As such, the aim of this study was to compare baseline and fatigued dynamic balance control, using reach distances and 95EV (95% ellipsoid volume), and evaluate the ability of 95EV to capture alterations in dynamic balance control, which are not detected by YBT reach distances.
As part of this descriptive laboratory study, 15 healthy participants completed repeated YBTs at 20, 10, and 0 min prior to and following a modified 60-s Wingate test that was used to introduce a short-term reduction in dynamic balance capability. Dynamic balance was assessed using the standard normalised reach distance method, while dynamic balance control during the reach attempts was simultaneously measured by means of the 95EV derived from an inertial sensor, worn at the level of the 4th lumbar vertebra.
Intraclass correlation coefficients for the inertial sensor-derived measures ranged from 0.76 to 0.92, demonstrating strong intrasession test-retest reliability. Statistically significant alterations ( < 0.05) in both reach distance and the inertial sensor-derived 95EV measure were observed immediately post-fatigue. However, reach distance deficits returned to baseline levels within 10 min, while 95EV remained significantly increased ( < 0.05) beyond 20 min for all 3 reach distances.
These findings demonstrate the ability of an inertial sensor-derived measure to quantify alterations in dynamic balance control, which are not captured by traditional reach distances alone. This suggests that the addition of an inertial sensor to the YBT may provide clinicians and researchers with an accessible means to capture subtle alterations in motor function in the clinical setting.
Y平衡测试（YBT）是最常用的临床动态平衡评估方法之一。研究表明，YBT在识别下肢损伤个体的平衡缺陷方面具有实用性。然而，仅基于伸展距离来量化动态平衡无法提供与伸展动作期间运动控制质量和运动策略选择相关的潜在重要信息。添加惯性传感器以捕获更详细的运动数据可能有助于在YBT伸展过程中对动态平衡控制进行低成本、易获取的量化。因此，本研究的目的是使用伸展距离和95EV（95%椭球体体积）比较基线和疲劳状态下的动态平衡控制，并评估95EV捕捉动态平衡控制变化的能力，而这些变化是YBT伸展距离无法检测到的。
作为这项描述性实验室研究的一部分，15名健康参与者在进行改良的60秒温盖特测试之前和之后的20、10和0分钟完成重复的YBT，该测试用于导致动态平衡能力的短期下降。使用标准归一化伸展距离方法评估动态平衡，同时通过佩戴在第四腰椎水平的惯性传感器得出的95EV来同时测量伸展尝试期间的动态平衡控制。
惯性传感器得出的测量值的组内相关系数范围为0.76至0.92，表明组内测试 - 重测可靠性强。疲劳后立即观察到伸展距离和惯性传感器得出的95EV测量值均有统计学显著变化（<0.05）。然而，伸展距离缺陷在10分钟内恢复到基线水平，而对于所有3个伸展距离，95EV在20分钟后仍显著增加（<0.05）。
这些发现表明，惯性传感器得出的测量值能够量化动态平衡控制的变化，而这是仅传统伸展距离无法捕捉到的。这表明在YBT中添加惯性传感器可能为临床医生和研究人员提供一种在临床环境中捕捉运动功能细微变化的便捷方法。
