Background

Dynamic balance control degrades during pregnancy, but it is not yet understood why. Mechanical aspects of the body should directly affect walking balance control, but we have recently published papers indicating that weight gains during pregnancy explain very little dynamic balance changes. Our goal was to determine if lower extremity joint kinematic changes are an indicator of walking balance control. This information is vital to understanding the route by which pregnancy increases fall risk.

Methods

Twenty-three pregnant women were tested at five different times in the 2nd and 3rd trimesters of pregnancy. Participants performed walking trials at a self-selected pace. Motion capture was used to measure joint kinematics (discrete and coordination variables) and body center of mass motion. Changes over time were statistically analyzed. Correlations between kinematics and walking balance were modelled with hierarchical multiple regression models.

Results

As pregnancy progresses, it appears that a more flexed hip posture could be driving lower extremity kinematic changes toward increased coordination between joints and increased knee and ankle motions. Walking balance changes were also detected through increased COM motion (lateral range of motion and velocity) in the lateral directions. However, there was little correlation between kinematic and balance changes (r² < 0.4). Strong correlations were only observed when all kinematics (including those that don’t ubiquitously change during pregnancy) were used in the regression model (r² > 0.7).

Significance

Our findings suggest that walking balance control is not altered by a common kinematic change between all pregnant women. While increased lateral center of mass motion should be expected with pregnancy, the kinematics leading to this increase may be person-specific. The cause of dynamic imbalance in each pregnant women (physiological, mechanical, and neurocognitive) may play an important role in determining the kinematic means by which lateral center of mass motion increases.

中文翻译：

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怀孕步态期间关节运动学与动态平衡控制之间的关系。

背景

动态平衡控制在怀孕期间会降低，但尚不清楚原因。身体的机械方面应直接影响步行平衡的控制，但是我们最近发表的论文表明，怀孕期间体重增加解释了动态平衡的变化很小。我们的目标是确定下肢关节运动学变化是否是步行平衡控制的指标。这些信息对于了解怀孕增加跌倒风险的途径至关重要。

方法

在怀孕的第2和第3个月的五个不同时间对23名孕妇进行了测试。参加者以自行选择的速度进行步行试验。运动捕捉用于测量关节运动学（离散和协调变量）和身体重心运动。对随时间的变化进行统计分析。运动学和步行平衡之间的相关性使用分层多元回归模型进行建模。

结果

随着怀孕的进行，似乎更加弯曲的髋部姿势可能会导致下肢运动学改变，从而导致关节之间的协调性增强以及膝盖和踝关节运动增加。通过在横向方向上增加COM运动（运动和速度的横向范围）也可以检测到步行平衡的变化。但是，运动和平衡变化之间几乎没有相关性（r ² <0.4）。只有在回归模型中使用了所有运动学（包括那些在怀孕期间没有普遍改变的运动学）时，才观察到强相关性（r ² > 0.7）。

意义

我们的发现表明，所有孕妇之间的运动学变化均不会改变步行平衡控制。虽然怀孕时预期横向质心的运动会增加，但导致运动增加的运动学因人而异。每个孕妇（生理，机械和神经认知）动态不平衡的原因可能在确定运动方式（质心运动的横向中心增加）中起重要作用。