Department of Kinesiology, University of Waterloo, 200 University Ave West, Waterloo, Ontario N2L 3G1, Canada.
Department of Kinesiology, University of Waterloo, 200 University Ave West, Waterloo, Ontario N2L 3G1, Canada.
Hum Mov Sci. 2020 Dec;74:102689. doi: 10.1016/j.humov.2020.102689. Epub 2020 Oct 29.
The movement strategy an individual uses to complete a lift can influence the resultant biomechanical exposure on their low back. We hypothesize that some lifters may choose a motor control strategy to minimize exposure to the low back, where others may not. Lower magnitudes of exposure to the low back coupled with less variability in lift-to-lift exposure and in features of movement strategy related to biomechanical exposure would support that such lifters consider minimizing exposure in their motor control strategy. We tested this hypothesis by investigating if differences in variability of low back exposure measures, as well as features of movement strategy related to resultant low back exposures differed across lifters. Twenty-eight healthy adults participated in the study where ten repetitions of a lifting task with the load scaled to 75% of participant's one-repetition maximum were completed. In all trials, whole-body kinematics and ground reaction forces were collected. Lifters were grouped as low, moderate or high relative exposure based on low back flexion angles and normalized L4/L5 extensor moments when lifting. Principal component analysis was used to identify independent movement strategy features, and statistical testing determined which features differed between high and low exposure lifts. Variability in low back exposures and movement features associated with relative biomechanical exposure were compared across lifter classifications. Significantly less variability was observed in low back exposures among the low exposure lifter group. Additionally, a trend towards lower variability in movement features associated with relative biomechanical exposure was also observed in low exposure lifters. These findings provide initial support for the hypothesis that some lifters likely define a motor control strategy that considers minimizing biomechanical exposure in addition to completing the lift demands. Future work should explore how state and trait-based factors influence an individual to consider biomechanical exposure within their motor control strategy in lifting.
个体完成举重动作所采用的运动策略会影响其腰部的生物力学负荷。我们假设，一些举重者可能会选择一种运动控制策略，将腰部的负荷降到最低，而另一些举重者则可能不会。腰部负荷的幅度较小，举重之间的负荷变化和与生物力学负荷相关的运动策略特征的变化也较小，这将支持这些举重者在其运动控制策略中考虑到最小化负荷。我们通过研究不同举重者之间腰部暴露测量值的变化性以及与腰部暴露相关的运动策略特征的变化性是否存在差异，来验证这一假设。28 名健康成年人参与了这项研究，他们完成了 10 次举重任务，负荷量为参与者最大重复次数的 75%。在所有试验中，都收集了全身运动学和地面反作用力数据。根据举重时腰部弯曲角度和归一化 L4/L5 伸肌力矩，将举重者分为低、中、高相对暴露组。使用主成分分析识别独立的运动策略特征，并通过统计检验确定高暴露和低暴露举重之间的特征差异。对不同举重者分类之间的腰部暴露和与相对生物力学暴露相关的运动特征的变化性进行了比较。低暴露组的腰部暴露变化性明显较小。此外，在低暴露举重者中，与相对生物力学暴露相关的运动特征的变化性也呈下降趋势。这些发现初步支持了这样一种假设，即一些举重者可能会定义一种运动控制策略，该策略不仅考虑完成举重任务，还考虑最小化生物力学负荷。未来的研究应该探讨状态和特质因素如何影响个体在举重时将生物力学暴露纳入其运动控制策略。
