Reeves Joanna, Jones Richard, Liu Anmin, Bent Leah, Nester Christopher
School of Health & Society, University of Salford, Salford M6 6PU, United Kingdom; School of Sport, Health and Exercise Science, Spinnaker Building, University of Portsmouth, PO1 2ER, United Kingdom.
School of Health & Society, University of Salford, Salford M6 6PU, United Kingdom.
J Biomech. 2021 Nov 9;128:110716. doi: 10.1016/j.jbiomech.2021.110716. Epub 2021 Aug 28.
Foot orthoses (FOs) are used to treat clinical conditions by altering the external forces applied to the foot and thereafter the forces of muscles and tendons. However, whether specific geometric design features of FOs affect muscle activation is unknown. The aim of this study was to investigate if medial heel wedging and increased medial arch height have different effects on the electromyography (EMG) amplitude of tibialis posterior, other muscles of the lower limb and the kinematics and kinetics at the rearfoot and ankle. Healthy participants (n = 19) walked in standardised shoes with i) a flat inlay; ii) a standard shape FOs, iii) standard FOs adjusted to incorporate a 6 mm increase in arch height, iv) and standard FOs adjusted to incorporate an 8° medial heel wedging and v) both the 6 mm increase in arch height and 8° increase in medial wedging. EMG was recorded from medial gastrocnemius, peroneus longus, tibialis anterior and in-dwelling tibialis posterior muscles. Motion and ground reaction force data were collected concurrently. Tibialis posterior EMG amplitude reduced in early stance with all FOs (ηp = 0.23-1.16). Tibialis posterior EMG amplitude and external ankle eversion moment significantly reduced with FOs incorporating medial wedging. The concurrent reduction in external eversion moment and peak TP EMG amplitude in early stance with medial heel wedging demonstrates the potential for this specific FOs geometric feature to alter TP activation. Medial wedged FOs could facilitate tendon healing in tibialis posterior tendon dysfunction by reducing force going through the TP muscle tendon unit.
足部矫形器（FOs）通过改变施加于足部的外力以及随后的肌肉和肌腱力量来治疗临床病症。然而，FOs的特定几何设计特征是否会影响肌肉激活尚不清楚。本研究的目的是调查内侧足跟楔形和内侧足弓高度增加对胫后肌、下肢其他肌肉的肌电图（EMG）幅度以及后足和踝关节的运动学和动力学是否有不同影响。健康参与者（n = 19）穿着标准化鞋子行走，分别为：i）平底鞋垫；ii）标准形状的FOs；iii）调整后使足弓高度增加6毫米的标准FOs；iv）调整后包含8°内侧足跟楔形的标准FOs；v）足弓高度增加6毫米且内侧楔形增加8°的FOs。记录了腓肠肌内侧头、腓骨长肌、胫骨前肌和内置胫后肌的EMG。同时收集了运动和地面反作用力数据。所有FOs在站立初期胫后肌EMG幅度均降低（ηp = 0.23 - 1.16）。包含内侧楔形的FOs使胫后肌EMG幅度和踝关节外侧外翻力矩显著降低。在站立初期，随着内侧足跟楔形，外侧外翻力矩和胫后肌EMG峰值幅度同时降低，这表明这种特定的FOs几何特征有可能改变胫后肌的激活。内侧楔形FOs可通过减少通过胫后肌肌腱单元的力来促进胫后肌腱功能障碍时的肌腱愈合。
