Department of Mechanical Engineering, University of Alberta, Edmonton, AB, Canada.
Division of Physical Medicine and Rehabilitation, University of Alberta, Edmonton, AB, Canada.
Biomed Eng Online. 2024 Jan 2;23(1):2. doi: 10.1186/s12938-023-01196-7.
Balance parameters derived from wearable sensor measurements during postural sway have been shown to be sensitive to experimental variables such as test duration, sensor number, and sensor location that influence the magnitude and frequency-related properties of measured center-of-mass (COM) and center-of-pressure (COP) excursions. In this study, we investigated the effects of test duration, the number of sensors, and sensor location on the reliability of standing balance parameters derived using body-mounted accelerometers.
Twelve volunteers without any prior history of balance disorders were enrolled in the study. They were asked to perform two 2-min quiet standing tests with two different testing conditions (eyes open and eyes closed). Five inertial measurement units (IMUs) were employed to capture postural sway data from each participant. IMUs were attached to the participants' right legs, the second sacral vertebra, sternum, and the left mastoid processes. Balance parameters of interest were calculated for the single head, sternum, and sacrum accelerometers, as well as, a three-sensor combination (leg, sacrum, and sternum). Accelerometer data were used to estimate COP-based and COM-based balance parameters during quiet standing. To examine the effect of test duration and sensor location, each 120-s recording from different sensor locations was segmented into 20-, 30-, 40-, 50-, 60-, 70-, 80-, 90-, 100-, and 110-s intervals. For each of these time intervals, time- and frequency-domain balance parameters were calculated for all sensor locations.
Most COM-based and COP-based balance parameters could be derived reliably for clinical applications (Intraclass-Correlation Coefficient, ICC ≥ 0.90) with a minimum test duration of 70 and 110 s, respectively. The exceptions were COP-based parameters obtained using a sacrum-mounted sensor, especially in the eyes-closed condition, which could not be reliably used for clinical applications even with a 120-s test duration.
Most standing balance parameters can be reliably measured using a single head- or sternum-mounted sensor within a 120-s test duration. For other sensor locations, the minimum test duration may be longer and may depend on the specific test conditions.
从姿势摆动期间可穿戴传感器测量得出的平衡参数已被证明对实验变量敏感，例如测试持续时间、传感器数量和传感器位置，这些变量会影响测量的质心（COM）和压力中心（COP）偏移的幅度和频率相关特性。在这项研究中，我们研究了测试持续时间、传感器数量和传感器位置对使用身体安装加速度计得出的站立平衡参数的可靠性的影响。
12 名没有任何先前平衡障碍病史的志愿者参加了这项研究。他们被要求进行两次 2 分钟的安静站立测试，两种不同的测试条件（睁眼和闭眼）。五个惯性测量单元（IMU）用于从每个参与者捕获姿势摆动数据。IMU 分别贴在参与者的右腿、第二骶骨、胸骨和左乳突。计算了单头、胸骨和骶骨加速度计以及三个传感器组合（腿、骶骨和胸骨）的感兴趣的平衡参数。加速度计数据用于在安静站立时估计基于 COP 和基于 COM 的平衡参数。为了检查测试持续时间和传感器位置的影响，从不同传感器位置的每个 120 秒记录中分割出 20、30、40、50、60、70、80、90、100 和 110 秒的间隔。对于这些时间间隔中的每一个，为所有传感器位置计算了时域和频域平衡参数。
大多数基于 COM 和基于 COP 的平衡参数都可以可靠地用于临床应用（组内相关系数，ICC≥0.90），测试持续时间分别至少为 70 和 110 秒。例外的是使用骶骨安装的传感器获得的基于 COP 的参数，尤其是在闭眼条件下，即使测试持续时间为 120 秒，也不能可靠地用于临床应用。
在 120 秒的测试持续时间内，使用单个头部或胸骨安装的传感器可以可靠地测量大多数站立平衡参数。对于其他传感器位置，测试持续时间可能更长，并且可能取决于特定的测试条件。
