Quirk D Adam, Trudel Raymond D, Hubley-Kozey Cheryl L
School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada.
School of Physiotherapy, Dalhousie University, Halifax, NS, Canada.
Front Sports Act Living. 2020 Jan 10;1:67. doi: 10.3389/fspor.2019.00067. eCollection 2019.
It is proposed that reduced function in one of the spinal systems (active, passive, and neural) outlined by Panjabi could increase the risk of experiencing a low back injury (LBI). Also proposed is that reduced function in any one system can be compensated for by adjusting the time-varying recruitment of trunk muscles. This study addressed whether those with reduced active system function (WEAK), measured as back extensor strength, would have different trunk muscle activation patterns than those with higher function (STRONG), and secondly whether this relationship would be modified following recovery from a LBI. Sixty men participated, 30 recently recovered from LBI (rLBI, 4-12 weeks post injury) and 30 who had not had a LBI in the last year (ASYM). ASYM and rLBI participants were separated into STRONG and WEAK sub-groups if their isometric back extensor strength was above or below their group median, respectively. Trunk electromyograms from 24 muscle sites were recorded during a highly controlled horizontal transfer task. Principal component analysis captured key muscle activation patterns (amplitude and temporal); then analysis of variance models tested for strength or group*strength effects on these patterns consistent with the two main objectives. Significant strength, or group by strength effects were found for 3/4 electromyographic comparisons. In general, the WEAK group required higher activation amplitudes of abdominal and back extensor muscles, and greater temporal responsiveness of back extensor muscles only to the changing external moments than those who were STRONG. Group by strength interactions found that participants in the rLBI group had greater differences between WEAK and STRONG participants for overall muscle activation amplitudes in both abdominal and back extensor muscles. This increase in muscle activation was interpreted as compensation for lower maximum force properties whereas the increased temporal responsiveness captured a greater need to modify the agonist back extensors muscle activation patterns only in response to changes in the dynamic moments. Interactions captured that the recent experience of pain (rLBI) modified the magnitude of adjustment in muscle activation patterns potentially adapting to an increased risk of instability (painful flare) events associated with a deficit (lower strength) of the active system.
有人提出，潘贾比概述的脊髓系统（主动、被动和神经）之一的功能降低可能会增加发生下背部损伤（LBI）的风险。还提出，任何一个系统的功能降低都可以通过调整躯干肌肉随时间变化的募集来补偿。本研究探讨了以背部伸肌力量衡量的主动系统功能降低的人（虚弱组）与功能较高的人（强壮组）的躯干肌肉激活模式是否不同，其次，这种关系在从LBI恢复后是否会改变。60名男性参与了研究，30名最近从LBI恢复（rLBI，受伤后4至12周），30名在过去一年中没有LBI（无症状组）。如果等长背部伸肌力量分别高于或低于其组中位数，无症状组和rLBI参与者被分为强壮组和虚弱亚组。在高度受控的水平转移任务中记录了来自24个肌肉部位的躯干肌电图。主成分分析捕捉关键肌肉激活模式（幅度和时间）；然后方差分析模型测试强度或组*强度对这些模式的影响，这与两个主要目标一致。在3/4的肌电图比较中发现了显著的强度或组×强度效应。一般来说，虚弱组比强壮组需要更高的腹部和背部伸肌激活幅度，并且仅对变化的外部力矩，背部伸肌需要更大的时间响应性。组×强度相互作用发现，rLBI组参与者在腹部和背部伸肌的整体肌肉激活幅度方面，虚弱组和强壮组之间的差异更大。这种肌肉激活的增加被解释为对较低最大力量特性的补偿，而增加的时间响应性表明仅为响应动态力矩变化而改变主动肌背部伸肌肌肉激活模式的更大需求。相互作用表明，近期的疼痛经历（rLBI）改变了肌肉激活模式的调整幅度，可能是为了适应与主动系统缺陷（较低强度）相关的不稳定（疼痛发作）事件风险增加。
