Therapeutic exercise has previously been shown to alter the static height of the medial longitudinal arch (MLA). It is still unknown, however, if these effects carry over into dynamic activities. PURPOSE: To determine if an 8-week foot strengthening exercise program increases static arch height and reduces vertical deformation of the MLA during mid-stance in running.METHODS: Thirty-four recreational runners (17 males, 17 females) have completed this ongoing study (age 24.06 ± 3.61 years, body mass 68.63 ± 12.95 kg, and height 173.34 ± 9.54 cm). To date, 22 subjects have been assigned to the control group (8 weeks of normal running) and 12 to the foot strengthening group (8 weeks of foot strengthening, along with normal running). Static arch height (SAH) and dynamic arch drop (DAD) were measured at baseline and following the 8-week intervention using Vicon motion analysis. Reflective markers were placed on the proximal and distal ends of the 1st and 5th metatarsals. These 4 markers were recorded in static double leg stance to estimate SAH, and in single leg mid-stance to give a measure of DAD during treadmill running at a self-selected pace. Ten-second trials were recorded at minutes 3 and 4 during running and DAD was evaluated for right and left feet by comparing arch height in mid-stance to the SAH. Following the intervention, data for SAH and DAD were compared across time points and statistical analysis performed to identify differences in the amount of change in SAH and DAD between groups. RESULTS: There was no difference noted in DAD between the groups as a whole, but the change in DAD from baseline to the end of week 8 was statistically significant for those in the foot strengthening group with an initial DAD of ≥ 3.80 mm (p < .028). There was also a statistically significant increase in SAH in the foot strengthening group compared to the control group (p = .013). CONCLUSIONS: These preliminary data suggest that the foot strengthening intervention was effective in increasing SAH compared to the control group. The intervention was most effective at decreasing DAD in those with the largest amount of DAD at baseline. At this time it is unknown whether this decrease in arch drop is associated with performance benefits or decreased injury risk in the recreational runner, and further research is needed to determine the clinical significance of these findings.

Foot posture is an important characteristic that can affect kinematics, plantar loading, and injury risk. Arch height is one common aspect of foot posture, and it is estimated that about 60% of the population has normal arches while 40% of the population is either pes planus or pes cavus. It is important to be able to accurately and reliably assess foot posture characteristics in order to propose interventions that could prevent injuries due to abnormal foot alignment. However, despite multiple classification metrics, many of the devices that are commonly used for foot posture measurements are not economically feasible for smaller clinics or research labs. Therefore, the first purpose of this study was to develop an affordable device to measure different foot posture characteristics. The Foot Posture Measurement System was developed and can measure total foot length, truncated foot length, foot width, dorsum height, and navicular height. This system was shown to have good to excellent validity (ICC = 0.908-0.994) and repeatability (ICC = 0.867-0.996) when compared to a 3D scanner. This device was then used in the second portion of this study, which evaluated the effects of ankle braces on plantar loading patterns in individuals with different foot postures. Contact area, peak force, force-time integral, and center of pressure were evaluated during a walk, run, and cut while the participant was unbraced, wearing a lace-up stabilizer brace, and wearing a semi-rigid brace. It was demonstrated that arch height did affect the maximum plantar forces during all tasks (p=0.001-0.047), as hypothesized based on previous studies. Additionally, this study found that ankle braces affected contact area (p=0.001-0.0014), maximum force (p<0.001 – p=0.043), and force-time integral (p<0.001 – p=0.015) during the walk, run, and cut. This is a novel finding and points to the potential for an impact of ankle braces on plantar loading during athletic activities, independent of foot type. / Master of Science / Foot posture is an important characteristic that can affect daily life and contribute to the risk of injury. Arch height is one common aspect of foot posture, and it is estimated that about 60% of the population has normal arches while 40% of the population is either high arched or low arched/flat footed. It is important to be able to accurately and reliably assess foot posture characteristics in order to propose interventions that could prevent injuries due to abnormal foot alignment. However, despite multiple classification metrics, many of the devices that are commonly used for foot posture measurements are not economically feasible for smaller clinics or research labs. Therefore, the first purpose of this study was to develop an affordable device to measure different foot posture characteristics. The Foot Posture Measurement System was developed and can measure five different length, width, and height characteristics of the foot. This system was shown to be valid when compared to a 3D scanner and repeatable between days. This device was then used in the second portion of this study, which evaluated the effects of ankle braces on individuals with different foot postures. Four different force and pressure variables were examined within the foot during a walk, run, and cut while the participant was unbraced, wearing a lace-up stabilizer brace, and wearing a semi-rigid brace. It was shown that arch height did alter plantar loading measures during all tasks, as hypothesized based on previous studies. Additionally, this study found that ankle braces affected all variables during the walk, run, and cut. This is a novel finding and points to the potential for an impact of ankle braces on plantar loading during athletic activities, independent of foot type.

付記する学位プログラム名: 充実した健康長寿社会を築く総合医療開発リーダー育成プログラム / 京都大学 / 0048 / 新制・課程博士 / 博士(人間健康科学) / 甲第22388号 / 人健博第74号 / 新制||人健||5(附属図書館) / 京都大学大学院医学研究科人間健康科学系専攻 / (主査)教授 黒木 裕士, 教授 高桑 徹也, 教授 妻木 範行 / 学位規則第4条第1項該当 / Doctor of Human Health Sciences / Kyoto University / DFAM