Background: The classification of foot type can be commonly determined by the height of the media longitudinal arch. The normalized arch height (NAH) is defined as the ratio of navicular or instep heights to the foot length or instep length. Objects: This study investigated the relationships among foot characteristics, such as foot length (FL), instep length (IL), navicular height (NH), and instep height (IH), in Korean young adults. Also, the distribution of foot type based on calculated NAH was assessed. Methods: Three-dimensional foot scanning data of young adults aged 20 to 39 years (total: 1,978; 974 male, 1,004 female) were obtained from the Korea Technology Standards Institute, and used for analyses. NAH was calculated as the following: NH/FL, IH/FL, IH/IL, NH/ IL. Spearman’s rank order correlation was used to identify correlations among variables. The Mann–Whitney U-test and chi-square test were used to compare the sex differences in foot characteristics and distribution of foot type. Results: FL and IL showed a very high correlation (r = 0.94). The correlations between FL or IL and IH (r = 0.50–0.57) were greater than those between FL or IL and NH (r = 0.23–0.72). Males had significantly larger values than females (p < 0.001), and the frequency of pes planus was significantly higher in females than in males (χ2 = 50.09, p < 0.001). Based on the IH/IL index, the neutral foot, pes planus and pes cavus distributed by 16%, 78%, and 6% respectively. Conclusion: Our results on foot arch distribution could be used as basic data in clinical or footwear fields, and our data on differences in arch structure according to sex may facilitate understanding of why injury to the lower limbs differs between males and females.

Background: Measurement of passive ankle dorsiflexion range of motion (ADROM) is often part of a physical therapy assessment. Objects: The objective of this study was to identify the effects of subtalar joint neutral position (SJNP) on passive ADROM according to knee position in young adults. Methods: We recruited 14 young adult participants for this study. Two examiners used a universal goniometer to measure passive ADROM with and without SJNP. Dorsiflexion force was applied to the forefoot until maximum resistance was reached in two knee positions (extension and 90˚ flexion) in the prone position. Subtalar joint position was also recorded at maximum ADROM. Passive ADROM was measured three times at different knee and subtalar joint positions, in random order. Two-way repeated-measures analysis of variance was used to compare the effects of subtalar joint and knee position on passive ADROM. Results: Passive ADROM was significantly lower with than without SJNP during both knee extension (mean difference: 7.4˚) and 90˚ flexion (mean difference: 16.9˚) (p<.01). Passive ADROM was significantly higher during 90˚ knee flexion than during knee extension both with (mean difference: 5.8˚) and without SJNP (mean difference: 15.2˚) (p<.01). The valgus position of the subtalar joint was significantly lower with than without SJNP during both knee extension (mean difference: 3.3˚) and 90˚ flexion (mean difference: 4.3˚) (p<.01). Conclusion: Our results indicate that the gastrocnemius may limit ankle dorsiflexion more than the soleus does. Greater dorsiflexion at the subtalar and midtarsal joints was observed during passive ADROM measurement without than that with SJNP; therefore, SJNP should be maintained for accurate measurement of ADROM.

Background: Passive straight leg raising (PSLR) is the common clinical test to measure of hamstring muscle length. Hip flexion angle contributes to change the lumbopelvic rotation during PSLR. Pressure biofeedback unit (PBU) is commonly used to detect lumbopelvic movement during lower limb movements. Thus, there may be the relationship between pressure of PBU and lumbopelvic motion during PSLR. Objects: The objective of this study was to determine the relationship between pressure of PBU and lumbopelvic motion during PSLR. Methods: Thirty two subjects participated in this study. A three-dimensional motion analysis system were used to measure the lumbopelvic angle during PSLR, while recording the pressure of PBU according to angle of PSLR by 10 degree increments. Pearson product moment correlations and linear regression analysis were used to describe the relationship between variables. Results: The results showed that there was a significant relationship between the lumbopelvic and angle of PSLR (Pearson’s r=.83, p<.05), between the pressure of PBU and angle of PSLR (Pearson’s r=.75, p<.05), and between lumbopelvic motion and pressure of PUB (Pearson’s r=.83, p<.05). Linear regression equation using lumbopevic angle as an independent factor was as follows: Pressure of PBU = 47.35 + (2.55 × angle of lumbopelvic motion) (R2=.69, p<.05). Conclusion: Results of the present study indicate that pressure of PBU can be used to indirectly detect the amounts of lumbobevic motion during muscle length test or stretching of hamstring.

The purposes of this study were to compare abductor hallucis (AbdH) muscle activity during toe curl exercise according to position of interphalangeal joint (IPJ). Fifteen healthy subjects with neutral foot were recruit for this study. All subjects performed toe curl exercise with towel while maintaining the IPJ in flexion (condition 1) and extension (condition 2). Toe curl exercise with towel was perform three trials for five second periods in each condition. Surface electromyography (EMG) activities were recorded from three muscles (AbdH, tibialis anterior, peroneous longus) in each condition. EMG activity was normalized to the value of maximal voluntary isometric contraction (%MVIC). The EMG activities acoording to position of IPJ were compared using a paired t-test. This study showed that the EMG activity of AbdH during toe curl exercise with IPJ extension significantly increased compared to those during toe curl exercise with IPJ flexion (p<.05). However, the EMG activity of tibialis anterior and peroneus longus were not significantly different between the conditions (p>.05). These results suggest that toe curl exercise with towel must be performed with extension of IPJ in order to strengthen intrinsic muscle in subjects with overuse injuries related to excessive pronation.

In many manufacturing occupations, industrial workers reported foot or lower leg problems such as discomfort, pain or orthopedic deformities. This study investigated the effects of two different working conditions upon assembly worker's perception of discomfort and foot pain associated with various body parts. Twenty-three male volunteers performed work in the factory. Ergonomic intervention has been to modify the flooring in an attempt to alleviate the problems associated with constrained standing and walking work. The worker's standing conditions consisted of standing on a hard floor while wearing shoe insoles. Questions were asked regarding body discomfort and foot pain. Significant differences in body discomfort and foot pain were found when comparing the overall effects of wearing shoe insoles on a hard floor (p<.05). This investigation indicated that shoe insoles reduced body discomfort and foot pain (p<.05).

The purpose of this study was to determine whether a relationship existed between foot type and the location of plantar callus in healthy subjects. Twenty-five healthy subjects with plantar callus were recruited for this study. Foot deformities were classified according to the operational definitions as 1) a compensated forefoot varus, 2) an uncompensated forefoot varus or forefoot valgus, or 3) a compensated rearfoot varus. The location of plantar callus was divided into two regions. Fourteen of the 19 feet with compensated forefoot varus and six of the 9 feet showed plantar callus at the second, third or fourth metatarsal head. Five of the 6 feet with uncompensated forefoot varus and twenty of the 16 feet with forefoot valgus showed plantar callus at the first or fifth metatarsal head. A significant relationship was found between foot type and location of callus (p<.01). The results support the hypothesis that certain foot types are associated with characteristic patterns of pressure distribution and callus formation. We believe diabetic patients with insensitive feet and with the types of foot deformity should be fit with foot orthoses and footwears that accommodate their respective deformity in a position as near to the subtalar joint as possible with the goal of preventing plantar ulceration.