Background: Weakness of evertor strength is controversial in chronic ankle instability (CAI). Ankle evertor muscles are attached to the toe joints as well as to the metatarsal bone. Therefore, it is necessary to consider toe joint position for the measurement of evertor strength. The purpose of this study was to compare ankle evertor strength and muscle activity during eversion with and without toe flexion (TF) in individuals with CAI and individuals in a healthy group. Methods: Fifteen subjects with CAI and 15 healthy subjects participated in this study. Isometric ankle evertor strength and muscle activity of the peroneus longus (PL), peroneus brevis (PB), and extensor digitorum longus (EDL) were measured during eversion with and without TF. Results: The results indicated a significant interaction effect in evertor strength ( P = .03) and no significant interaction effect on EMG of the PL ( P = .08), PB ( P = .12), and EDL ( P = .28). However, measurements of muscle activity of the PL and PB between eversion with and without TF revealed a significant difference in the CAI group ( P < .01) and no significant difference in the healthy group (PL: P = .07; PB: P = .13). Conclusion: The results indicated that subjects with CAI had increased EDL compensation and reduced selective activation of the PL and PB during eversion. Clinical Relevance: Our findings suggest that clinicians should consider the activation of EDL when training the evertor of patients with CAI.

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Background:The serratus posterior inferior (SPI) muscle originates from the spinous process of T11-L2 and inserts at the lower border of the 9-12th ribs. This muscle is involved in thoracolumbar rotation and stability. Several positions can be used to improve trunk stability; the quadruped position is a good position for easily maintaining a neutral spine. In particular, during one arm lifting, various muscles act to maintain a neutral trunk position, and the SPI is one of these muscles. If trunk stability is weakened, uncontrolled trunk rotation may occur at this time. Tape can be used to increase trunk stability. There have been no studies on the effect of taping applied to the SPI muscle on thoracolumbar junction (TLJ) stability.Objects: This study compared the TLJ rotation angle between three different conditions (without taping, transverse taping, and SPI muscle direction taping).Methods: Thirty subjects were recruited to the study (18 males and 12 females). The TLJ rotation angle was measured during one arm lifting in a quadruped position (ALQP). Two taping methods (transverse and SPI muscle direction taping) were applied, and the TLJ rotation angle was measured in the same movement.Results: SPI muscle direction taping significantly reduced TLJ rotation compared to that without taping (p < 0.001) and with transverse taping (p < 0.001). There was a significant difference in the TLJ rotation angle between transverse taping and SPI muscle direction taping (p < 0.017). Conclusion:SPI muscle direction taping reduces the TLJ rotation angle during ALQP. Therefore, SPI muscle direction taping is one method to improve TLJ stability and reduce uncontrolled TLJ rotation during ALQP.

Flatfoot Foot orthoses Genu valgumBackground: Pronated foot posture (PFP) contributes to excessive dynamic knee valgus (DKV). Although foot orthoses such as medial arch support (MAS) are widely and easily used in clinical practice and sports, few studies have investigated the effect of MAS on the improvement of DKV during stair descent in individuals with a PFP. Moreover, no studies reported the degree of improvement in DKV according to the severity of PFP when MAS was applied.Objects: This study aimed to examine the immediate effect of MAS on DKV during stair descent and determine the correlation between navicular drop distance and changes in DKV when MAS is applied.Methods: Twenty individuals with a PFP (15 males and five females) participated in this study. The navicular drop test was used to measure PFP severity. The frontal plane projection angle (FPPA) was calculated under two conditions, with and without MAS application, using 2-dimensional video analysis.Results: During stair descent, the FPPA with MAS (173.1° ± 4.7°) was significantly greater than that without MAS (164.8° ± 5.8°) (p < 0.05). There was also a significant correlation between the navicular drop distance and improvement in the FPPA when MAS was applied (r = 0.453, p = 0.045). Conclusion:MAS application can affect the decrease in DKV during stair descent. In addition, MAS application should be considered to improve the knee alignment for individuals with greater navicular drop distance.