Firouzabadi Ali, Arjmand Navid, Pan Fumin, Zander Thomas, Schmidt Hendrik
Julius Wolff Institute, Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Berlin, Germany.
Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
Front Bioeng Biotechnol. 2021 Nov 2;9:750862. doi: 10.3389/fbioe.2021.750862. eCollection 2021.
Manual material handling (MMH) is considered as one of the main contributors to low back pain. While males traditionally perform MMH tasks, recently the number of females who undertake these physically-demanding activities is also increasing. To evaluate the risk of mechanical injuries, the majority of previous studies have estimated spinal forces using different modeling approaches that mostly focus on male individuals. Notable sex-dependent differences have, however, been reported in torso muscle strength and anatomy, segmental mass distribution, as well as lifting strategy during MMH. Therefore, this study aimed to use sex-specific models to estimate lumbar spinal and muscle forces during static MHH tasks in 10 healthy males and 10 females. Motion-capture, surface electromyographic from select trunk muscles, and ground reaction force data were simultaneously collected while subjects performed twelve symmetric and asymmetric static lifting (10 kg) tasks. AnyBody Modeling System was used to develop base-models (subject-specific segmental length, muscle architecture, and kinematics data) for both sexes. For females, female-specific models were also developed by taking into account for the female's muscle physiological cross-sectional areas, segmental mass distributions, and body fat percentage. Males showed higher absolute L5-S1 compressive and shear loads as compared to both female base-models (25.3% compressive and 14% shear) and female-specific models (41% compressive and 23.6% shear). When the predicted spine loads were normalized to subjects' body weight, however, female base-models showed larger loads (9% compressive and 16.2% shear on average), and female-specific models showed 2.4% smaller and 9.4% larger loads than males. Females showed larger forces in oblique abdominal muscles during both symmetric and asymmetric lifting tasks, while males had larger back extensor muscle forces during symmetric lifting tasks. A stronger correlation between measured and predicted muscle activities was found in females than males. Results indicate that female-specific characteristics affect the predicted spinal loads and must be considered in musculoskeletal models. Neglecting sex-specific parameters in these models could lead to the overestimation of spinal loads in females.
人工搬运（MMH）被认为是导致腰痛的主要因素之一。传统上男性从事MMH任务，但最近从事这些体力要求较高活动的女性人数也在增加。为了评估机械损伤风险，以往大多数研究使用不同的建模方法来估计脊柱受力，这些方法大多侧重于男性个体。然而，在躯干肌肉力量和解剖结构、节段质量分布以及MMH过程中的 lifting 策略方面，已经报道了显著的性别差异。因此，本研究旨在使用特定性别的模型来估计10名健康男性和10名女性在静态MHH任务期间的腰椎脊柱和肌肉受力。在受试者执行十二个对称和不对称静态举重（10公斤）任务时，同时收集运动捕捉、选定躯干肌肉的表面肌电图和地面反作用力数据。使用 AnyBody 建模系统为两性开发基础模型（特定受试者的节段长度、肌肉结构和运动学数据）。对于女性，还通过考虑女性的肌肉生理横截面积、节段质量分布和体脂百分比来开发特定女性模型。与女性基础模型（压缩力高25.3%，剪切力高14%）和特定女性模型（压缩力高41%，剪切力高23.6%）相比，男性的L5-S1绝对压缩和剪切负荷更高。然而，当将预测的脊柱负荷归一化到受试者体重时，女性基础模型显示出更大的负荷（平均压缩力9%，剪切力16.2%），特定女性模型显示出比男性小2.4%和大9.4%的负荷。在对称和不对称举重任务中，女性在腹斜肌中表现出更大的力量，而男性在对称举重任务中背部伸肌力量更大。与男性相比，女性中测量和预测的肌肉活动之间的相关性更强。结果表明，特定女性特征会影响预测的脊柱负荷，在肌肉骨骼模型中必须予以考虑。在这些模型中忽略特定性别的参数可能会导致对女性脊柱负荷的高估。
