Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
Gait Posture. 2019 Sep;73:305-314. doi: 10.1016/j.gaitpost.2019.08.004. Epub 2019 Aug 7.
Maintaining body centre of mass (CoM) lowering velocity within manageable/safe limits during stair descent can be problematic for older individuals due to reduced ranges of motion at the involved joints (ankle and knee) and a reduced ability to generate adequate joint moments at the extremes in joint ranges of motion. These problems are likely to magnify in circumstances where the distance of lowering increases, or when misjudging the height of lowering.
How does a 50% increase in standard stair riser-height affect control of CoM velocity and acceleration of older people during stair descent?
Fifteen older (75 ± 3 years) and seventeen young (25 ± 4 years) healthy adults descended a 4-step staircase, at two riser-heights: 170 mm, 255 mm. Changes in peak vertical CoM acceleration and velocity, and lower-limb joint kinetics (moments, work) during landing and lowering phases of stair descent were assessed using a mixed-design repeated measures analysis of variance.
Peak CoM accelerations and velocities during landing and lowering were lower in older compared to young adults and increased in both groups at 255 mm riser-height. Duration of lowering also increased, particularly for older adults. Peak ankle moments during landing and lowering, which were lower in older compared to young adults, increased when descending from 255 mm riser-height, whilst the peak knee moment reduced. Both groups produced increased landing-limb negative (eccentric) ankle joint work when descending from 255 mm, but increases were greater for older adults (87.8%) compared to young (76.1%).
Descending stairs became more challenging in both age groups as riser-height increased. Older adults adopted a strategy of reducing CoM velocity to lessen the eccentric landing demands. In both groups, but more so older adults, there was a greater reliance on using leading-limb eccentric plantarflexion at 255 mm riser-height compared to 170 mm, to arrest/control increased downward CoM velocity and acceleration during landing.
由于参与关节（脚踝和膝盖）的活动范围减小以及在关节活动范围的极限处产生足够关节力矩的能力降低，老年人在从楼梯上下来时，将身体质心（CoM）的降低速度保持在可管理/安全范围内可能会出现问题。当降低的距离增加时，或者当错误判断降低的高度时，这些问题可能会放大。
标准楼梯踏步高度增加 50%如何影响老年人在楼梯下降过程中 CoM 速度和加速度的控制？
15 名老年人（75±3 岁）和 17 名年轻人（25±4 岁）健康成年人分别以 2 种踏步高度（170mm、255mm）下降 4 级楼梯。使用混合设计重复测量方差分析评估楼梯下降过程中着陆和下降阶段的垂直 CoM 加速度和速度以及下肢关节动力学（力矩、功）的峰值变化。
与年轻人相比，老年人在着陆和下降过程中的 CoM 加速度和速度峰值较低，在两个组中，当踏步高度为 255mm 时，这些值均增加。下降的持续时间也增加了，尤其是对于老年人。与年轻人相比，老年人在着陆和下降过程中的峰值踝关节力矩较低，当从 255mm 踏步高度下降时，峰值踝关节力矩增加，而峰值膝关节力矩降低。当从 255mm 踏步高度下降时，两组的着陆腿负（离心）踝关节工作都增加，但老年人（87.8%）的增加幅度大于年轻人（76.1%）。
随着踏步高度的增加，两个年龄组下降楼梯的难度都增加了。老年人采用降低 CoM 速度的策略来减轻离心着陆的需求。在两个组中，但老年人更明显，与 170mm 相比，在 255mm 踏步高度时，更多地依赖于使用前导腿的离心跖屈来阻止/控制着陆时增加的 CoM 速度和加速度。
