The ankle joint, including the talocrural and subtalar joints, plays an important role in human locomotion. Sex differences in walking patterns among young and old adults have been studied; however, little information exists on sex-based variations in talocrural and subtalar joint kinematics during walking. Thus, the purpose of this study was to investigate sex-based differences in the talocrural and subtalar joint kinematics during walking. We obtained lateral fluoroscopic images from 10 male and 7 female healthy volunteers during stance phase, and determined the three-dimensional bone orientations using 3D-2D model-image registration techniques to compare sex-specific differences. The orientation of the tibia, talus, and calcaneus were comparable in the static reference position. Sex-based differences in the range of motion were observed in talocrural dorsi/plantar flexion, subtalar eversion/inversion and subtalar external/internal rotation while walking. The ranges of motion in talocrural dorsi/plantar flexion (male, 13 ± 4°; female, 17 ± 3°), subtalar eversion/inversion (male, 8 ± 3°; female, 11 ± 3°) and subtalar external/internal rotation (male, 5 ± 2°; female, 7 ± 2°) were significantly larger in females than in males. Differences in rearfoot kinematics between males and females may reflect anatomic, physiologic and locomotor differences. Greater bone rotations in the female hindfoot may predispose women to different pathologies, or merit different treatments, than men based upon subtalar and talocrural kinematics during gait.

Abdominal muscles may be both morphologically and functionally affected by pregnancy. Dysfunction of the muscles can lead to persistent postpartum low back pain. The recovery process of the abdominal muscles following childbirth is not well understood. This study aimed to demonstrate the changes in the thickness and contractile function of abdominal muscles during the first six months postpartum. Nine perinatal and 15 nulliparous females participated. The thicknesses and contraction/relaxation thickness ratios of the rectus abdominis (RA), external abdominal oblique (EO), internal abdominal oblique (IO), and transverse abdominis (TrA) were measured using ultrasound images from 36–39 weeks’ gestation until six months postpartum. The RA, IO, and TrA muscles were thinner in perinatal females than controls at 36–39 weeks of gestation (4.8 vs. 9.47 mm (RA), 5.45 vs. 7.73 mm (IO), 2.56 vs. 3.38 mm (TrA), respectively). The thinner IO muscle persisted for six months after delivery. The decreased TrA thickness ratio persisted until four months post-delivery. Abdominal muscle thickness and contractile function decreased in the postpartum period. Therefore, abdominal muscle exercises might help prevent postpartum symptoms; however, because deterioration of muscle function is significant in the first four months, careful attention should be paid to exercise intensity. The study limitation was a relatively small sample size, thus future studies should involve more participants.

Ankle sprains are the most prevalent injuries, and elevated fear avoidance beliefs after ankle sprain episodes could inhibit athletic performance and contribute to residual symptoms, such as functional and/or mechanical instability. However, it remains unclear how fear avoidance beliefs differ according to conditions of posttraumatic sequelae. The purpose of this study was to determine whether fear of movement/reinjury differed between individuals with and without functional ankle instability (FI, NFI) and healthy controls (CON) and to examine the relationship between fear and ankle joint laxity by sex. Participants (115 male athletes, 105 female athletes) completed the Identification of Functional Ankle Instability, Athlete Fear Avoidance Questionnaire (AFAQ), Tampa Scale for Kinesiophobia (TSK), and ankle joint laxity test. Total 168 athletes (79 males, 89 females) data were eligible for analysis. The results demonstrated that fear of movement/reinjury was lower in individuals in the absence of functional ankle instability although they experienced ankle sprain (FI; TSK=38.6±4.5, AFAQ=27.4±6.2, NFI; TSK=35.7±5.6, AFAQ=24.5±6.6). The fear of movement/reinjury had correlation with ankle joint laxity only in female athletes (TSK; r=0.285, p=0.013, AFAQ; r 0=0.322, p=0.045).

Prolonged running results in lowering of the foot arch and a low arch is associated with subsequent chronic injuries. Foot posture alteration and recovery following a marathon run remain unknown. Therefore, the present study aimed to evaluate foot posture alteration following a full marathon run. The three‐dimensional foot posture data of 11 collegiate runners were obtained using an optical foot scanner system before, and immediately, 1 day, 3 days, and 8 days after a full marathon. The navicular height and arch height ratio significantly decreased from before to immediately, 1 day, 3 days, and 8 days after the marathon (navicular height: before, 44.2 ± 5.0 mm; immediately after, 39.4 ± 5.5 mm; 1 day, 37.7 ± 6.2 mm; 3 days, 38.7 ± 5.5 mm; 8 days, 37.6 ± 5.7 mm; arch height ratio: before, 18.4 ± 1.9; immediately after, 16.5 ± 2.5; 1 day, 15.7 ± 2.5; 3 days, 16.2 ± 2.6; 8 days, 15.6 ± 2.2, P < 0.001, respectively). By contrast, the dorsal height significantly increased from before and immediately after to 1 day after the marathon, and then significantly decreased until 8 days after the marathon (P < 0.001). These results indicate that the recovery patterns of the dorsal and navicular heights following a marathon did not coincide; the dorsal height rose temporally at 1 day after and subsequently decreased, but the navicular height decreased throughout the 8‐day period after the marathon. More than one week may be necessary for sufficient foot alignment recovery from marathon‐induced changes.

Long-distance running results in lowering of the foot medial longitudinal arch, but it is unknown whether the left and right arches decrease equally. This study aimed to determine whether foot arch asymmetry increases upon completion of a full marathon and to identify factors capable of explaining the degree of asymmetry of navicular height and navicular height displacement. The three-dimensional foot posture data of 74 collegiate runners were obtained using an optical foot scanner system before (PRE) and immediately after (POST) a full marathon. The navicular height and arch height ratio (normalised navicular height by foot length) of both feet significantly decreased from PRE to POST full marathon completion (44.3 ± 6.3 mm versus 40.8 ± 6.5 mm, 17.8 ± 2.5 versus 16.6 ± 2.7, respectively; p < 0.001, both). The asymmetry of the arch height ratio was significantly greater POST than PRE marathon. Multiple linear regression analysis indicated that the POST-race Asymmetry Index (AI) of navicular height was significantly predicted by the PRE-race AI of navicular height; navicular height displacement was predicted by PRE-race navicular height and the marathon time. Full marathon running induced increasing asymmetry and lowering of the medial longitudinal arch in runners.