Background: Changes in foot sole shape can result in plantar muscle weakness, lack of proprioception, increased ankle instability, and an inability to balance. Objectives: To investigated whether different floor surfaces influenced the effect that short-foot exercises have on the foot core system of healthy individuals. Design: Pretest-posttest control group experimental design. Methods: This exercise shortens the length of the foot by raising the medial longitudinal arch, strengthening the intrinsic muscle of the sole, and maintaining the shape of the medial longitudinal arch. Results: There was a significant difference in the angle of the medial longitudinal arch in the mat exercise group (MEG) and vibration exercise group (VEG) before and after the intervention (P<.05). As the arch angle decreased, the arch height increased. Post hoc analysis showed that there was no difference between the floor exercise group (FEG) and MEG or between the MEG and VEG (P>.05). In terms of the weight distribution index (WDI, there was a significant difference in the MEG and VEG (P<.05) but not in the FEG before and after the intervention (P>.05). The post hoc analysis results showed that there was no difference between the FEG and MEG (P>.05). Conclusion: Various methods to improve the strength of intrinsic muscles of the sole are more effective than no stimulation, and that short-foot exercise combined with sensory stimulation can be recommended for maintaining and increasing the medial longitudinal arch.

Background: The MLA is supported by both the abductor hallucis (ABH) and the extrinsic muscles. Insufficient muscular support may lower the MLA when the body’s weight is applied to the foot. The short foot exercise (SFE) is effective in increasing the height of the MLA for people with flat feet. Most of the research related to the SFE has simply evaluated the efficiency of the exercise using enhanced ABH electromyography (EMG) activation. Since the tibialis anterior (TA), peroneus longus (PER), and ABH are all involved in supporting the MLA, a new experiment design examining the EMG of the selected muscles during SFE should be applied to clarify its effect. Objects: Therefore, this study aimed to clarify the effect of the SFE in different ankle position on the MLA angle and the activation of both the intrinsic and extrinsic muscles and to determine the optimal position. Methods: 20 healthy subjects and 12 subjects with flat feet were recruited from Yonsei University. The surface EMG and camera were used to collect muscle activation amplitude of TA, PER, and ABH and to capture the image of MLA angle during SFE. The subjects performed the SFE while sitting in three different ankle positions—neutral (N), dorsiflexion (DF) at 30 degrees, and plantar flexion (PF) at 30 degrees. Results: ABH EMG amplitudes were significantly greater in N and DF than in PF (p<.05). Muscle activation ratio of TA to ABH was the lowest in PF (p<.05). MLA angle in both groups significantly decreased in PF (p<.01). The TA and ABH was activated at the highest level in DF. However, in PF, subjects significantly activated the ABH and PER with relatively low activation of TA. Conclusion: Therefore, researchers need to discuss which SFE condition most effectively use the arch support muscle for flat foot.

Background: Short foot exercise (SFex) is often prescribed and performed in the sport and rehabilitation fields to strengthen intrinsic foot muscles. However, SFex is difficult to perform because of lack of feedback methods. Objects: The aim of this study was to compare the effects of SFex with and without electromyography (EMG) biofeedback on the medial longitudinal arch (MLA) of healthy individuals who maintained a static standing position. Methods: All participants (14 males and 12 females) were randomly divided into two groups (biofeedback and non-biofeedback groups). The EMG activity of the abductor hallucis (AbdH) and tibialis anterior (TA) and the MLA angle on the dominant leg side were measured with the participant in the standing position in the pre- and post-intervention conditions. The intervention session consisted of 15 minutes of SFex with (biofeedback group) or without (non-biofeedback group) EMG biofeedback. The groups were compared using two-way repeated measures analysis of variance. Results: The post-intervention activities of the AbdH muscle (p<.05) and the AbdH/TA ratio (p<.05) were significantly greater in the biofeedback group than in the non-biofeedback group. The activity of the TA (p<.05) and the MLA angle (p<.05) in the biofeedback group were significantly lower in the post-intervention condition than in the pre-intervention condition. Conclusion: The present findings demonstrate that the combination of SFex and EMG biofeedback can effectively facilitate the muscle activity of the AbdH and strengthen the medial longitudinal arch.

The aims of this study were to investigate the correlation between the electromyographic (EMG) activity of the abductor hallucis (AbdH) and the amount of pressure measured by a pinch gauge (PG), and to compare the EMG activity of AbdH and the pressure measured by the PG during short foot (SF) exercise in subjects with pes planus and in subjects with a neutral foot alignment. Fourteen subjects were recruited for this study (pes planus group=7; neutral foot alignment group=7). A surface EMG was used to collect AbdH activity, and a PG was positioned under the first metatarsophalangeal joint to measure the pressure produced by the first metatarsal head during the SF exercise. The AbdH activity and the pressure measured by the PG showed a positive good correlation (r=.80, p<.05). The EMG activity of the AbdH and the pressure measured by the PG were significantly lower for subjects with pes planus than for subjects with a neutral foot alignment (p<.05). Based on these findings, the PG can be recommended as an effective instrument for evaluating the performance of the AbdH. It may also be beneficial for monitoring how well the SF exercise is performed, and for providing visual feedback to patients with pes planus during SF exercise in a clinical setting.

신체의 이동과 정지 시 동적 안정성과 균형성에 영향을 미치는 인솔에 대해 분석하였다. 특히 종족궁의 아치를 인위적으로 서서 체중을 가한 상태와 같은 평상시와 동일한 상태로 지속적으로 지지하였을 경우에 개별적인 균형능력의 변화를 추적하였다. 정상적인 신체 조건과 발모양을 유지하는 20대 남녀 각 10명씩 20명을 대상으로 종족궁 내측아치를 측정하여 아치를 지지하는 인솔을 개별적으로 제작하였으며, Tetrax 균형성 평가 장비를 이용하여 COP의 변위 패턴과 힘점의 이동거리를 착용 전, 후 비교하였다. 아치를 지지하는 인솔을 착용한 실험군이 균형능력 평가에서 약 22% 정도 상승되는 결과를 나타내었다. 본 비교 실험을 통해 종족궁의 내측아치를 지지하는 인솔 착용이 신체의 균형능력을 향상시키는데 도움이 되는 것으로 나타났다.