This study investigates how external vertical forces on the pelvis change the stability of stairmill climbing and other gait parameters such as kinematics and muscle activity. We use a Tethered Pelvic Assist Device (TPAD) to apply forces on the pelvis during continuous ascent on a stairmill. Ten young healthy subjects participated in three one-minute stair ascent with no force, a 10% body weight (BW) downward force, and a 10% BW upward force applied on the pelvis. The stability is determined by evaluating the base of support (BoS) and margin of stability (MoS). Kinematics and muscle activities were used to characterize the biomechanical changes. The results show that the upward forces applied on the pelvis decreased the (i) MoS by 1.84cm in the lateral direction, 2.07cm in the anterior direction, (ii) double stance phase by 1.85%, and (iii) the knee flexion by 5°. Furthermore, the peak activation levels of the muscles rectus femoris (RF), vastus lateralis (VL), and left gastrocnemius decreased. In contrast, the downward forces applied on the pelvis increased (i) the MOS by 1.5cm in the anterior direction and (ii) mean activation levels of RF and VL muscles. This study provides insights into the effects of applied vertical forces on the pelvis during stair ascent. These findings contribute to the understanding of the gait parameter changes and their relation with stability. Results could be used as a basis for designing training protocols to improve balance during stair ascent.

中文翻译：

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在骨盆上向上和向下施加力的楼梯上升过程中的稳定性


这项研究调查了骨盆上的外部垂直力如何改变爬楼梯的稳定性以及其他步态参数（例如运动学和肌肉活动）。我们使用系留骨盆辅助装置 (TPAD) 在楼梯上连续上升时对骨盆施加力。 10 名年轻健康受试者参加了 3 次一分钟无力爬楼梯、10% 体重 (BW) 向下力和对骨盆施加 10% BW 向上力的实验。稳定性是通过评估支撑基础 (BoS) 和稳定边际 (MoS) 来确定的。运动学和肌肉活动用于表征生物力学变化。结果表明，施加在骨盆上的向上力使 (i) MoS 横向减少 1.84 厘米，向前减少 2.07 厘米，(ii) 双站立阶段减少 1.85%，(iii) 膝关节屈曲减少5°。此外，股直肌（RF）、股外侧肌（VL）和左侧腓肠肌的峰值激活水平下降。相反，施加在骨盆上的向下力使 (i) MOS 向前增加 1.5 厘米，以及 (ii) RF 和 VL 肌肉的平均激活水平。这项研究深入了解了上楼梯过程中施加的垂直力对骨盆的影响。这些发现有助于理解步态参数的变化及其与稳定性的关系。结果可以用作设计训练方案的基础，以改善爬楼梯过程中的平衡。