Fluctuation of fine motor skills throughout the menstrual cycle in women.

The effect of the menstrual cycle on fine motor skills is unclear. This study determined whether the menstrual cycle affected fine motor skills and related neural activities. Nineteen women with regular menstrual cycles were tested for fine motor skills using two types of tasks: grooved pegboard task (GPT), which evaluates motor control with high freedom of movements, and force modulation task (FMT), which evaluates more complex and fine motor control with low freedom of movements. We also assessed primary motor cortex intracortical circuits and sensorimotor integration using paired-pulse transcranial magnetic stimulation to reveal why the menstrual cycle affects fine motor skills. The present study indicated that fine motor skills assessed by FMT varied throughout the menstrual cycle while those measured by GPT did not. These results suggest that fine motor skills requiring more complex and fine control may be affected by the menstrual cycle. Additionally, changes in fine motor skills throughout the menstrual cycle may be associated with the severity of menstruation-related symptoms.

Relationship between joint structure of the first tarsometatarsal joint and its degeneration.

This study aimed to elucidate the relationship between joint structures of the first tarsometatarsal and articular facet degeneration. A total of 100 feet from 50 cadavers were examined. The articular facets of the first metatarsal and medial cuneiform were categorized into four types based on the superior and inferior facets' separation, and the formation of the inferior lateral facet on the lateral plantar prominence: Type I, a single facet with no separation or inferior lateral facet; Type II-a, two facets with separation but no inferior lateral facet; Type II-b, two facets, no separation, but with an inferior lateral facet; Type III, three facets with separation and an inferior lateral facet. When both bone types matched, they were defined as Type I, Type II-a, Type II-b, and Type III joints, respectively; unmatched types were classified as Unpair joints. The severity of articular cartilage degeneration on both bones was assessed using a 5-point scale. The degeneration grade was compared among joint types. Type III joints exhibited significantly milder articular cartilage degeneration in medial cuneiform compared to Type II-a, II-b, Unpair joints. The formation of inferior lateral facet and separation of the superior and inferior facets might be crucial for the joint's stability.

Dynamics of the suprapatellar bursa during knee joint extension.

PURPOSE: The suprapatellar bursa is located in the proximal deep layer of the patella and is thought to reduce tissue friction by changing from a single-membrane structure to a double-membrane structure during knee joint motion. However, the dynamics of the suprapatellar bursa have only been inferred from positional relationships, and the actual dynamics have not been confirmed. METHODS: Dynamics of the suprapatellar bursa during knee joint motion were observed in eight knees of four Thiel-fixed cadavers and the angle at which the bursa begins to show a double membrane was revealed. The flexion angles of knee joints were measured when the double-membrane structure of the suprapatellar bursa began to appear during knee joint extension. RESULTS: The suprapatellar bursa changes from a single membrane to a double-membrane structure at 91 ± 4° of flexion, when the knee joint is moved from a flexed position to an extended position. CONCLUSION: The suprapatellar bursa may be involved in limitations to knee joint range of motion and pain at an angle of approximately 90°. Further studies are needed to verify whether the same dynamics are observed in living subjects.

Changes in the mechanical properties of the thigh and lower leg muscle-tendon units during the early follicular and early luteal phases.

Background: This study aimed to determine changes in the muscle and tendon stiffness of the thigh and lower leg muscle-tendon units during the early follicular and early luteal phases, and check for possible relations between muscle and tendon stiffness in each phase. Methods: The sample consisted of 15 female university students with regular menstrual cycles. The basal body temperature method, ovulation kit, and salivary estradiol concentration measurement were used to estimate the early follicular and early luteal phases. A portable digital palpation device measured muscle-tendon stiffness in the early follicular and early luteal phases. The measurement sites were the rectus femoris (RF), vastus medialis (VM), patellar tendon (PT), medial head of gastrocnemius muscle, soleus muscle, and Achilles tendon. Results: No statistically significant differences in the thigh and lower leg muscle-tendon unit stiffness were seen between the early follicular and early luteal phases. Significant positive correlations were found between the stiffness of the RF and PT (r = 0.608, p = 0.016) and between the VM and PT (r = 0.737, p = 0.002) during the early luteal phase. Conclusion: The present results suggest that the stiffness of leg muscle-tendon units of the anterior thigh and posterior lower leg do not change between the early follicular and early luteal phases and that tendons may be stiffer in those women who have stiffer anterior thigh muscles during the early luteal phase.

Relationship between first tarsometatarsal ligament morphology and its continuity with the fibularis longus and first tarsometatarsal joint degeneration.

This study explored the relationship between the morphological characteristics of the first tarsometatarsal ligaments and fibularis longus (FL) and the severity of articular cartilage degeneration in the first tarsometatarsal joint. Sixty legs from 30 cadavers were examined. The plantar, dorsal, and medial first tarsometatarsal ligaments were classified by fiber bundle number, and their morphological characteristics (fiber bundle length, width, thickness) were measured. The FL was categorized by its continuity with the plantar first tarsometatarsal ligament (PTML): Type A, connection with the PTML only on the first metatarsal; Type B, connection along the entire PTML; and Type C, no connection with the PTML. The severity of articular cartilage degeneration was assessed in four stages. No significant differences in cartilage degeneration among ligament types were found. Negative correlations were observed between the fiber bundle width and thickness of the PTML and the severity of cartilage degeneration. FL was classified as Type A in 68%, Type B in 27%, and Type C in 5% of feet. The fiber bundle thickness of the PTML in Type B was greater than in other types. Our findings suggest that smaller fiber bundle width and thickness in the PTML may be associated with severe cartilage degeneration. The FL had continuity with the PTML in 95% of feet and could enhance the mechanical strength of the PTML in Type B feet.

Effects of transcutaneous auricular vagus nerve stimulation at left cymba concha on experimental pain as assessed with the nociceptive withdrawal reflex, and correlation with parasympathetic activity.

The aim of this study was to clarify the effects of transcutaneous auricular vagus nerve stimulation (taVNS) to the left cymba concha on the pain perception using nociceptive withdrawal reflex (NWR), which is known to be associated with chronic pain, and to investigate whether there is a relationship between taVNS-induced suppression of the NWR and parasympathetic activation. We applied either 3.0 mA, 100 Hz taVNS for 120 s on the left cymba concha (taVNS condition) or the left earlobe (Sham condition) for 20 healthy adults. NWR threshold was measured before (Baseline), immediately after (Post 0), 10 min (Post 10) and 30 min after (Post 30) stimulation. The NWR threshold was obtained from biceps femoris muscle by applying electrical stimulation to the sural nerve. During taVNS, electrocardiogram was recorded, and changes in autonomic nervous activity measured by heart rate variability (HRV) were analyzed. We found that the NWR thresholds at Post 10 and Post 30 increased compared with baseline in the taVNS group (10 min after: p = .008, 30 min after: p = .008). In addition, increased parasympathetic activity by taVNS correlated with a greater increase in NWR threshold at Post 10 and Post 30 (Post 10: p = .003; Post 30: p = .001). The present results of this single-blinded study demonstrate the pain-suppressing effect of taVNS on NWR threshold and suggest that the degree of parasympathetic activation during taVNS may predict the pain-suppressing effect of taVNS after its application.

Validation of anterior ankle soft tissue dynamics and shear modulus for anterior ankle impingement syndrome after ankle fracture surgery.

Anterior ankle impingement syndrome (AAIS) has been reported to account for a high percentage of complications following ankle fracture surgery. The soft tissue etiology of AAIS is thought to be thickening and inflammation of the anterior ankle soft tissues intervening anteriorly at the tibiotalar joint, causing pain and functional limitation during dorsiflexion. However, the effects of anterior ankle soft tissue dynamics and stiffness on AAIS have yet to be clarified. This study aimed to determine the relationship between AAIS and the anterior ankle soft tissue thickness change ratio and shear modulus using ultrasonography (US). The participants were 20 patients with ankle joint fractures (AO classification A, B) who had undergone open reduction and internal fixation and 20 healthy adults. The evaluation periods were 3 months and 6 months postoperatively. US was used to delineate the tibialis anterior tendon, extensor hallucis longus tendon, and the extensor digitorum longus tendon over the talus and tibia on a long-axis image. Anterior ankle soft tissue thickness was measured as the shortest distance from the most convex part of the talus to the tendon directly above it. The Anterior ankle soft tissue thickness change ratio was determined by dividing the value at 0° dorsiflexion by the value at 10° plantarflexion. The same images as for the anterior soft tissue thickness measurement were drawn for the shear modulus measurement, and the average shear modulus (kPa) was calculated using shear-wave elastography. There was no significant difference in the thickness change ratio between the postoperative and healthy groups. Compared with the healthy group, the shear modulus was significantly higher at 3 and 6 months in the postoperative group (p < 0.01). The shear elastic modulus at 6-month postoperative group was significantly lower than at 3-month postoperative group (p < 0.01). Anterior ankle joint soft tissue stiffness may increase after surgery for an ankle fracture.

Snack and Nutrient Intake Status of Top-Level Female University Athletes: A Cross-Sectional Study.

Ensuring proper energy, nutrient intake, and sleep is vital for athlete health and competitiveness. Despite previous studies investigating the nutrient intake among top-level collegiate female athletes in Japan, the status of snack consumption remains unclear. This study addressed this gap by surveying 70 top-level female university athletes. The survey included a self-administered diet history questionnaire, a qualitative food intake frequency survey, and a survey on snack and dietary supplement use. The results revealed a low frequency of snack intake (2.1 ± 2.3 days/week), with 55.7% of athletes reporting snack consumption. The energy intake in the snack-intake group was significantly higher than that in the without-snack-intake group (31.5 ± 10.0 vs. 26.6 ± 9.92 kcal/kg of BM, p = 0.047). Similarly, carbohydrate intake was significantly higher in the snack-intake group than in the without-snack-intake group (4.84 ± 1.71 vs. 3.96 ± 1.65 g/kg of BM/day, p = 0.035). However, neither group reached the recommended value of 5-8 g/kg of BM/day during the medium training period. Overall, this study emphasizes inadequate energy intake even among athletes with a high snack intake frequency, highlighting the necessity to enhance overall food consumption and underscoring the importance of nutritional education for incorporating appropriate complementary meals to improve performance.

Differences and relationships between weightbearing and non-weightbearing dorsiflexion range of motion in foot and ankle injuries.

BACKGROUND: This study aimed to: (1) identify assessment methods that can detect greater ankle dorsiflexion range of motion (DROM) limitation in the injured limb; (2) determine whether differences in weightbearing measurements exist even in the absence of DROM limitations in the injured limb according to non-weightbearing measurements; and (3) examine associations between DROM in the weightbearing and non-weightbearing positions and compare those between a patient group with foot and ankle injuries and a healthy group. METHODS: Eighty-two patients with foot and ankle injuries (e.g., fractures, ligament and tendon injuries) and 49 healthy individuals participated in this study. Non-weightbearing DROM was measured under two different conditions: prone position with knee extended and prone position with knee flexed. Weightbearing DROM was measured as the tibia inclination angle (weightbearing angle) and distance between the big toe and wall (weightbearing distance) at maximum dorsiflexion. The effects of side (injured, uninjured) and measurement method on DROM in the patient groups were assessed using two-way repeated-measures ANOVA and t-tests. Pearson correlations between measurements were assessed. In addition, we analyzed whether patients without non-weightbearing DROM limitation (≤ 3 degrees) showed limitations in weightbearing DROM using t-tests with Bonferroni correction. RESULTS: DROM in patient groups differed significantly between legs with all measurement methods (all: P < 0.001), with the largest effect size for weightbearing angle (d = 0.95). Patients without non-weightbearing DROM limitation (n = 37) displayed significantly smaller weightbearing angle and weightbearing distance on the injured side than on the uninjured side (P < 0.001 each), with large effect sizes (d = 0.97-1.06). Correlation coefficients between DROM in non-weightbearing and weightbearing positions were very weak (R = 0.17, P = 0.123) to moderate (R = 0.26-0.49, P < 0.05) for the patient group, and moderate to strong for the healthy group (R = 0.51-0.69, P < 0.05). CONCLUSIONS: DROM limitations due to foot and ankle injuries may be overlooked if measurements are only taken in the non-weightbearing position and should also be measured in the weightbearing position. Furthermore, DROM measurements in non-weightbearing and weightbearing positions may assess different characteristics, particularly in patient group. LEVEL OF EVIDENCE: Level IV, cross-sectional study.

Comparison of trunk muscle activity during lumbar stabilization exercises on stable and unstable surfaces.

BACKGROUND: Lumbar stabilization exercises (LSE) provide dynamic trunk stability, promote muscle strength and endurance, and improve low back pain rehabilitation and performance. OBJECTIVE: To clarify the differences in trunk muscle activity during LSEs on stable and different unstable surfaces. METHODS: Fifteen healthy males performed three exercises (elbow-toe, hand-knee, and side bridge) on stable (floor) and unstable surfaces. Muscle activity of the bilateral rectus abdominis, internal oblique, external oblique, and erector spinae were recorded. Data were compared using the Friedman test. Pairwise comparisons were performed using Wilcoxon's signed rank test if significant differences were observed. RESULTS: In the elbow-toe exercise, muscle activity of the rectus abdominis and right internal oblique increased in the following order: floor, low-difficulty, and high-difficulty unstable surface. In the hand-knee exercise, muscle activity of the internal oblique on the lower-extremity elevated side, external oblique, and erector spinae on the upper-extremity elevated side were greater on unstable surface exercise performance. In the side bridge exercise, rectus abdominis muscle activity was highest on a high-difficulty unstable surface. CONCLUSION: Trunk muscle activity increased during exercise on unstable surfaces. Since the effects of unstable surfaces vary depending on muscle and exercise types, exercise difficulty and surface stability must be considered accordingly.

Elbow valgus stress during towel drills in college baseball players.

BACKGROUND: In baseball players with elbow injuries, towel drills are clinically used before initiating active throwing exercises to gradually increase stress across the elbow. However, elbow valgus torque during towel drills remains unknown. Moreover, towel drills and active ball throws might have different relationships between biomechanical metrics, such as elbow stress, arm slot, and arm speed. Therefore, the aims of this study were 1) to demonstrate the difference in elbow valgus stress between towel drills and active ball throws and 2) to evaluate the correlation between elbow valgus torque and other biomechanical metrics including arm slot and arm speed in towel drills and active ball throws. METHODS: Seventeen healthy college baseball players performed three towel drills using a face towel, short foam tube, and long foam tube, followed by full-effort throwing on flat ground. Each participant completed five consecutive trials of each task, and the elbow valgus torque, arm slot, and arm speed were measured using wearable sensors. One-way repeated analysis of variance and post-hoc tests were used to determine the differences in biomechanical metrics among the tasks. Furthermore, the correlation between the elbow valgus torque and other metrics was evaluated using Pearson correlation coefficients. RESULTS: Elbow valgus torque was lower in towel drills compared to that of active ball throws; however, the stress during towel drills using a face towel reached almost 80% of the maximum effort of active ball throws. There was no relationship between elbow valgus stress and arm slot in either the towel or active ball throw tasks. However, a higher arm speed was associated with greater elbow valgus torque in towel drills, whereas no relationship between elbow stress and arm speed was found in active ball throws. CONCLUSION: Precaution must be taken in athletes following a progressive throwing program because elbow valgus stress reaches almost 80% of the full-effort throw, even when using a face towel in a towel drill. Hence, the subjective intensity must be controlled even in towel drills to gradually increase the medial elbow stress. Moreover, the mechanisms underlying changes in elbow stress may differ between towel drills and active ball throws. Future investigations on the difference between towel drills and active ball throws may help understand the underlying mechanism of alterations in elbow valgus torque during the throwing movement.

Arch height flexibility is associated with plantar fascia tension during running.

BACKGROUND: Plantar fascia tension is considered to cause plantar fasciitis, and medial longitudinal arch decrease is believed to be a risk factor for plantar fasciitis. Arch height index (AHI) and arch height flexibility (AHF) are useful indicators for evaluating medial longitudinal arch. However, the relationship between plantar fascia tension during running and these indicators remain unclear. RESEARCH QUESTION: Are the foot characteristics in AHI and AHF that represent medial longitudinal arch related to plantar fascia tension during running? METHODS: Twenty-two male participants enrolled in this study. Foot characteristics required for calculating AHI and AHF were measured using the AHI measurement system. AHI was defined as the height from the floor to the dorsum of the foot divided by the truncated foot length with 10% or 50% load. AHF was defined as the change in arch height from the 10% and 50% loads. Marker trajectories of the foot and force plate data during running were measured using a three-dimensional motion analysis system and a force plate. Based on the measured data, the peak values of the plantar fascia tension were analyzed. Pearson's correlation was used to determine the relationship between foot characteristics and plantar fascia tension. RESULTS: No significant correlation was found between AHI in the 10% load condition and plantar fascia tension (r = -0.36, p = 0.09) or between AHI in the 50% load condition and plantar fascia tension (r = -0.148, p = 0.515). In contrast, a significant moderate positive correlation was observed between AHF and plantar fascia tension (r = 0.568, p < 0.01). SIGNIFICANCE: AHF is a change in arch height between sitting and standing positions, can be easily used to evaluate plantar fascia tension in clinical settings. This study implies that evaluating AHF is a useful tool in considering plantar fascia tension during running.

Elevated IL-1ß and Comparable IL-1 Receptor Antagonist Levels Are Characteristic Features of L-PRP in Female College Athletes Compared to Male Professional Soccer Players.

Autologous platelet-rich plasma (PRP) therapy has been becoming popular for the treatment of musculotendinous injuries among athletes. However, for individual and practical variations, clinical success is hardly predictable. To overcome this difficulty, we have been exploring possible criterion candidates for monitoring its clinical effectiveness. In this study, we focused on sex-based differences in young elite athletes and compared the biochemical compositions of their PRP. Leukocyte-rich PRP (L-PRP) was manually prepared from blood samples collected from male professional soccer players (mPSPs) (n = 25) and female college athletes (fCAs) (n = 36). Platelet-derived growth factor-BB (PDGF-BB), transforming-growth factor-ß1 (TGFß1), platelet factor-4 (PF4), interleukin-1ß (IL-1ß), and IL-1 receptor antagonist (IL-1RA) were quantified using an enzyme-linked immunosorbent assay. The levels of PDGF-BB, TGFß1, and PF4 in L-PRP were significantly higher in mPSPs than in fCAs. Conversely, IL-1ß and IL-1RA were detected at significantly and slightly higher levels, respectively, in fCAs than in mPSPs. Our findings suggest that, even though L-PRP from fCAs may have lower potential to induce cell growth and differentiation than that of mPSPs, due to the latter's higher capacity to control inflammation, it does not necessarily imply that PRP treatment in fCAs is less effective. Thus, these cytokine levels should be checked before PRP therapy.

Posterior deltoid shoulder tightness and greater contralateral lower limb muscle strength are associated with swimmers' shoulder pain.

OBJECTIVES: To identify factors associated with shoulder pain in swimmers based on elastic muscle modulus, joint range of motion, and isometric muscle strength. DESIGN: Cohort study. METHODS: Forty-eight competitive swimmers without shoulder pain (age: 18-28 years; men: 29) were followed-up for 6 months. Baseline measurements of the elastic modulus of the pectoralis minor, supraspinatus, infraspinatus, posterior deltoid, and pectoralis minor muscles were obtained using shear wave elastography. Range of motion and isometric strength were measured using a goniometer and a hand-held dynamometer, respectively. A questionnaire was administered weekly for 6 months to determine shoulder pain occurrence. Each item was compared between shoulders with and without pain at baseline. For participants with shoulder pain exceeding 2 weeks, shear wave elastography and range of motion at baseline (pre pain) and during follow-up (post pain) were compared. RESULTS: Of 46 swimmers followed-up for 6 months, 20 reported shoulder pain. 14 swimmers with pain were evaluated twice. Participants with shoulder pain during follow-up had significantly higher posterior deltoid and pectoralis minor stiffness at baseline and high lower extremity isometric muscle strength contralateral to the shoulder with pain compared to those without pain (p < 0.05). Swimmers with pain exceeding 2 weeks exhibited no differences in ultrasound shear wave elastography and range of motion at baseline and after pain onset. CONCLUSIONS: Posterior deltoid and pectoralis minor muscle stiffness, and high isometric lower extremity strength contralateral to the shoulder with pain may be associated with shoulder pain development, thereby indicating the importance of maintaining posterior deltoid and pectoralis minor muscle flexibility during conditioning.

Participant attention on the intervention target during repetitive passive movement improved spinal reciprocal inhibition enhancement and joint movement function.

This study aimed to evaluate the effects of the participant's attention target during repetitive passive movement (RPM) intervention on reciprocal inhibition (RI) and joint movement function. Twenty healthy adults participated in two experiments involving four attention conditions [control (forward attention with no RPM), forward attention (during RPM), monitor attention (monitor counting task during RPM), ankle joint attention (ankle movement counting task during RPM)] during 10-min RPM interventions on the ankle joint. Counting tasks were included to ensure the participant's attention remained on the target during the intervention. In Experiment 1, RI was measured before, immediately after, and 5, 10, 15, 20, and 30 min after the RPM intervention. In Experiment 2, we evaluated ankle joint movement function at the same time points before and after RPM intervention. The maximum ankle dorsiflexion movement (from 30° plantar flexion to 10° dorsiflexion) was measured, reflecting RI. In Experiment 1, the RI function reciprocal Ia inhibition was enhanced for 10 min after RPM under all attention conditions (excluding the control condition. D1 inhibition was enhanced for 20 min after RPM in the forward and monitor attention conditions and 30 min after RPM in the ankle joint attention condition. In Experiment 2, the joint movement function decreased under the forward and monitor attention conditions but improved under the ankle joint attention condition. This study is the first to demonstrate that the participant's attention target affected the intervention effect of the RI enhancement method, which has implications for improving the intervention effect of rehabilitation.

Characterization of Leukocyte- and Platelet-Rich Plasma Derived from Female Collage Athletes: A Cross-Sectional Cohort Study Focusing on Growth Factor, Inflammatory Cytokines, and Anti-Inflammatory Cytokine Levels.

Platelet-rich plasma (PRP) has been increasingly used in sports medicine owing to its various advantages. The purpose of our project was to standardize the parameters before performing large-scale clinical trials in the near future to precisely evaluate individual PRP quality. To examine the effects of regular exercise on PRP quality, this study focused on young female athletes, who have been relatively less studied. Blood samples were obtained from female college athletes (n = 35) and ordinary healthy adults (n = 30), which were considered as controls, and leukocyte-rich PRP (L-PRP) was prepared manually. Body composition indices were determined using a bathroom weight scale equipped with an impedance meter. Growth factors and cytokines were quantified using ELISA kits. Platelet-derived growth factor-BB (PDGF-BB) and Transforming-growth factors ß1 (TGFß1) levels (per platelet) in L-PRP were significantly lower in female athletes than in controls. In contrast, Interleukin-1ß and Interleukin 1 receptor antagonist (IL-1RA) levels (per platelet and L-PRP) in L-PRP were significantly higher in athletes, and this difference was more prominent in IL-1RA. These findings suggest that L-PRP from athletes may facilitate the inflammatory phase of the healing process by regulating the pro-inflammatory and anti-inflammatory balance. These chemical compositions can be adopted as "must-check" parameters to characterize individual PRP preparations prior to clinical trials.

Ultrasound Imaging of Subtalar Joint Instability for Chronic Ankle Instability.

The purpose of this study was to develop the assessment of subtalar joint instability with chronic ankle instability (CAI) using ultrasonography. Forty-six patients with anterior talofibular ligament (ATFL) abnormalities and a history of ankle sprain were divided into CAI (21.2 ± 5.9 y/o, 7 males and 17 females) and asymptomatic groups (21.0 ± 7.4 y/o, 9 males and 12 females) on the basis of subjective ankle instability assessed using the CAIT and the Ankle Instability Instrument Tool (AIIT). Twenty-six age-matched feet participated in a control group (18.9 ± 7.0 y/o, 9 males and 17 females). Ultrasound measurements of the width of the posterior subtalar joint facet were obtained at rest and maximum ankle inversion (subtalar joint excursion; STJE). The differences in STJE among the three groups were assessed by one-way ANOVA. The relationship between STJE and subjective ankle instability was assessed using Spearman's correlation tests. The STJE value was significantly greater in the CAI group (2.3 ± 0.8 mm) than in the asymptomatic (1.0 ±0.4 mm) and control groups (0.8 ±0.2 mm) (p < 0.001, effect size: 0.64). STJE had significant negative correlations with CAIT (r = -0.71, p < 0.01), and significant positive correlations with AIIT (r = 0.74, p < 0.01). The cut-off value to distinguish between the CAI and asymptomatic groups was 1.7 mm using the ROC curve.

Anatomical study of type classification and surface area of attachment sites for tibialis anterior tendon.

BACKGROUND: The purpose of this study was to clarify the attachment types of the tibialis anterior tendon (TAT) in Japanese fixed cadavers and to determine the attachment site area in three dimensions. METHODS: We examined 100 feet from 50 Japanese cadavers. The TAT was classified according to differences in the number of fiber bundles as: Type I, with one fiber bundle; Type II, with two fiber bundles; and Type III, with three fiber bundles. The attachment site area of the TAT was measured using a three-dimensional scanner. RESULTS: Cases were Type II in 95% and Type III in 5%, with no cases of Type I identified. In Type II, mean attachment site areas were 85.2 ± 18.2 mm2 for the medial cuneiform bone (MCB) and 72.4 ± 19.0 mm2 for the first metatarsal bone (1 MB), showing a significantly larger area for MCB than for 1 MB. CONCLUSIONS: These findings suggest the possibility of ethnic differences in TAT attachment types and suggest that TAT attachments in Japanese individuals are highly likely to be Type II, with rare cases of Type III. Accurate measurement of attachment site areas is possible with appropriate three-dimensional measurements.

Effects of remote facilitation on ankle joint movement: Focusing on occlusal strength and balance.

Background: Remote facilitation refers to teeth occlusion-activated spinal cord activity resulting in increased trunk and limb muscle strength. Facilitation depends on dentition-related pressure during occlusion and masticatory muscle contraction strength. Aims: This study aimed to clarify the neurophysiological phenomenon and mechanisms by which occlusal strength and balance affect leg muscle activity and smooth joint movement execution. Materials & Methods: To examine occlusal strength, three conditions were set: no contact between teeth and Moderate- and Maximum-strength occlusion (No-bite, Moderate, and Max conditions, respectively). To assess occlusal balance, we measured occlusal forces and calculated the left-right force ratio. We designated the sides with higher and lower occlusal pressure as hypertonic and hypotonic, respectively. We assessed ankle dorsiflexion movements with joint movement and isometric tasks. Results: The rate of joint development and peak ankle dorsiflexion torque were significantly higher under occlusion (moderate and max compared to No-bite conditions), and the joint movement performance time was significantly shorter under Moderate compared to No-bite conditions. The joint movement execution time change rate from No-bite to Moderate condition was significantly lower on the Hypertonic side. Joint movement function was most improved under Moderate conditions. Discussion: While remote facilitation improves with higher occlusal strength, leading to increased muscle strength, there is optimal occlusion intensity in joint movement. Moreover, an occlusal balance-dependent imbalance exists in remote facilitation between the Hyper- and Hypotonic sides. Conclusion: Thus, low-intensity occlusion is optimal for smooth joint movement, and unbalanced occlusion results in asymmetrical motor function facilitation.

Relationship between Joint and Ligament Structures of the Subtalar Joint and Degeneration of the Subtalar Articular Facet.

This study aimed to clarify the relationship between the joint and ligament structures of the subtalar joint and degeneration of the subtalar articular facet. We examined 50 feet from 25 Japanese cadavers. The number of articular facets, joint congruence, and intersecting angles were measured for the joint structure of the subtalar joint, and the footprint areas of the ligament attachments of the cervical ligament, interosseous talocalcaneal ligament (ITCL), and anterior capsular ligament were measured for the ligament structure. Additionally, subtalar joint facets were classified into Degeneration (+) and (-) groups according to degeneration of the talus and calcaneus. No significant relationship was identified between the joint structure of the subtalar joint and degeneration of the subtalar articular facet. In contrast, footprint area of the ITCL was significantly higher in the Degeneration (+) group than in the Degeneration (-) group for the subtalar joint facet. These results suggest that the joint structure of the subtalar joint may not affect degeneration of the subtalar articular facet. Degeneration of the subtalar articular facet may be related to the size of the ITCL.