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Taurine enhances physical performance; however, the underlying mechanism remains unclear. This study examined the effect of taurine on the overtime dynamics of blood glucose concentration (BGC) during endurance exercise in rats. Male F344 rats were subjected to transient treadmill exercise until exhaustion following 3 weeks of taurine supplementation or non-supplementation (TAU and CON groups). Every 10 min during exercise, BGC was measured in blood collected through cannulation of the jugular vein. Gluconeogenesis-, lipolysis-, and fatty acid oxidation-related factors in the plasma, liver, and skeletal muscles were also analyzed after 120-min run. Exercise time to exhaustion was significantly longer with taurine supplementation. BGC in the two groups significantly increased by 40 min and gradually and significantly decreased toward the respective exhaustion point. The decline in BGC from the peak at 40 min was significantly slower in the TAU group. The time when the once-increased BGC regressed to the 0-time level was significantly and positively correlated with exercise time until exhaustion. At the 120-min point, where the difference in BGC between the two groups was most significant, plasma free fatty acid concentration and acetyl-carnitine and N-acetyltaurine concentrations in skeletal muscle were significantly higher in the TAU group, whereas glycogen and glucogenic amino acid concentrations and G6Pase activity in the liver were not different between the two groups. Taurine supplementation enhances endurance capacity by delaying the decrease in BGC toward exhaustion through increases of lipolysis in adipose tissues and fatty acid oxidation in skeletal muscles during endurance exercise.

[Purpose] Understanding the neuromuscular cooperativeness functions when an athlete is fatigued is essential in preventing sports injuries and examining post-injury return standards. This study aimed to investigate the kinds of changes in neuromuscular cooperativeness before and after fatigue loading. [Participants and Methods] Fifteen female university athletes were examined for chronological changes in neuromuscular cooperativeness. Muscle fatigue loading was performed using BIODEX (180°/s) during knee flexion and extension exercises on one side. Surface electromyography of the rectus femoris and biceps femoris was performed on both sides before and immediately, 5 min, 10 min, and 15 min after loading. The switching silent period and pre-motor time were calculated from the electromyographic waveforms to indicate neuromuscular cooperativeness. [Results] The switching silent periods in the loading side immediately and 5 min after loading were significantly prolonged compared with that before loading. [Conclusion] Muscle fatigue loading instantaneously prolonged the switching silent period and decreased the neuromuscular cooperativeness. Furthermore, recovery generally occurred within 10 minutes after loading.

Objective: In 2020, coronavirus disease-2019 (COVID-19) became the cause of a pandemic. In response, the Japan Sports Agency issued warnings about secondary damage to health, such as the threat to physical and mental well-being due to the lack of exercise in this situation. In this study, we report on cross-sectional and longitudinal examinations of standing trunk flexion to evaluate how temporary long-term school closures affected musculoskeletal function in elementary school students. Patients and Methods: All children in one public elementary school in T-city during the school years 2019 and 2020 were included in this study. A digital forward flexion meter was used to measure standing trunk flexion. Results: In this study, 284 (284/289: 98.3%) and 266 (266/274: 97.1%) children in school years 2020 and 2019, respectively, were found to have valid data for cross-sectional analysis. The standing trunk flexion did not show significant differences between grades or sexes. In the longitudinal analysis, the results of the comparison of standing trunk flexion in children for two consecutive years revealed significant differences only between grades 3 and 4 (P

The purpose of the present study was to investigate the effects of using a combination of static stretching and aerobic exercise on muscle tendon unit stiffness and muscle strength in the ankle plantar-flexor muscles. Fifteen healthy males (23.3 ± 2.7 years, 170.3 ± 6.5 cm, 64.9 ± 8.7 kg) received three different interventions, in random order. Intervention 1 received 10 min of aerobic exercise after five cycles of one minute of static stretching. Intervention 2 received 10 min of aerobic exercise before the static stretching. Intervention 3 received 5 min of aerobic exercise both before and after the static stretching. The range of motion of ankle dorsiflexion, stretch tolerance, muscle tendon unit stiffness, peak torque of ankle plantarflexion, and the amplitude of electromyography were measured. In all interventions, the range of motion and stretch tolerance significantly increased (

This study compared the cost of screening with outcomes and verified the utility of a screening program. This cross-sectional study included all elementary and junior high school students from Tsukuba city who underwent musculoskeletal screening in 2016; 19,583 students were included. Written marksheet type questionnaires were distributed that focused on reporting scoliosis, torticollis, flat foot, and pain, among other symptoms. Using information from the questionnaire, face-to-face screening was performed by a doctor on-campus and/or orthopedic surgeons. Students with abnormalities on screening were identified and referred for a hospital visit. The screening, questionnaire, reasons for and number of hospital visits, examination, treatment, and their individual costs were examined. Hospital visits were recommended to 532/19,583 (2.7%) students after musculoskeletal screening. Among them, 250 and 129 students visited other and our hospitals, respectively. Overall, 11 students required treatment. Costs associated with screening, hospital examination, and treatment totaled to ¥8,526,351; 129 students visited our institution, of whom 11 (8.5%) required treatment. Among them, 10/11 and 1/11 were treated using orthotic and operative treatments, respectively. If scoliosis surgery may be prevented by musculoskeletal screening and orthotic treatment, it is possible that the outcomes may justify the examination costs.

Objective: In 2016, Japan started conducting musculoskeletal examinations that included "limb status" of students as an essential item. Our institution implemented a unified musculoskeletal examination for all public elementary and junior high schools in T-city. In this study, we aimed to report the progress in the past 4 years. Patients and Methods: The Tsukuba Childhood Locomotive-Organ Screening Sheet (T-CLOSS), which is a questionnaire that includes some nationwide-recommended questions, was prepared and distributed to students. Results of the questionnaires were analyzed, and the orthopedic surgeon conducted examinations for the extracted items. From these questionnaires, the ratio of each item, rate of advisory for screening, and content of the advisory were investigated. Results: During 2016-2019, musculoskeletal examinations were conducted in every public schools, with nearly 20,000 students in T-city. The consultation advisory rate was 6.7% in 2019. Of the 524 students who received the third screening recommendation, the actual consultation rate was 248 (40.8%). After the third screening, the proportion of students requiring treatment and outpatient visits was 46.7% (n=248), which accounted for 1.2% of all elementary and junior high school students in the city. Conclusion: We reported the results of 4-year musculoskeletal examinations in a city. In our screening, we distributed a uniform questionnaire throughout the city, and orthopedic surgeons performed secondary examinations of identified students in all schools. This appears to be an advanced effort to prevent musculoskeletal impairment in students. We hope to conduct more sophisticated musculoskeletal examinations using our results, aiming at early detection, early treatment, and improvement of musculoskeletal function in elementary and junior high school students.

Understanding lower limb kinematics and postural control in different directions of single-leg landings is critical to evaluate postural control and prevent lower limb injuries. However, foot and ankle kinematics and postural control during single-leg landings in different directions are less known.Does the difference in the direction of single-leg landing affect the foot kinematics on the frontal plane and dynamic postural stability?A cross-sectional study was conducted. Forty-nine male collegiate soccer players performed single-leg forward (FL), 45° lateral (LL), and medial (ML) direction landings. The lower limb, foot (rearfoot, midfoot, forefoot), and ankle kinematics during an impact phase were evaluated, and a curve analysis was performed using a statistical parametric mapping method to compare the three landings. The three landings were compared in terms of postural control parameters, including time to stabilization (TTS), peak of ground reaction forces (GRFs), root-mean-square of the mediolateral GRFs for 0-0.4 s (GRFML0.4), loading rate, and magnitude of horizontal GRFs from 0-0.4 s (HGRF-0.4), 0.4-2.4 s (HGRF-2.4), and 3.0-5.0 s.Ankle and rearfoot kinematics in LL exhibited smaller eversion and pronation positions than FL and ML (p0.01). The TTS-mediolateral (TTS-ML) was longer in the LL than in FL and ML (p0.001). The GRFML0.4, HGRF-0.4, and -2.4 in the LL and ML were greater than those in the FL (p0.001).Directions of single-leg landing affect foot and ankle kinematics and postural stability. Specifically, the LL exhibits more inverted ankle and supinated rearfoot positions, and longer TTS-ML. Thus, the LL may induce stretching of the lateral ankle ligament. These findings can help understand foot kinematics and assess dynamic postural control.

The purpose of this study was to investigate the characteristics of musculoskeletal findings in elementary and junior high school children using 1-year prospective longitudinal data from a long-term survey. Data from 1209 (97.6%) of 1239 children were analyzed. The main results were as follows: “Limitation of standing forward flexion” was particularly frequent in the 4th grade in all children and in the 5th grade in boys and girls going on to the next grade. “Flat foot” was particularly frequent in boys in the 1st, 6th, and 8th grades going on to the next grade. In girls, the frequency of “flat foot” was particularly high in the 1st, 4th, and 8th grades going on to the next grade. Findings of scoliosis appeared more often in girls than in boys. Minor findings such as “asymmetrical height of the shoulder and scapula”, first appearing in the 4th and 5th grades, may be linked to the increase in “Rib hump” in the stage entering junior high school; it is important to pay attention to such changes in the scoliosis findings. This 1-year prospective longitudinal analysis demonstrated that the frequency of some musculoskeletal findings was high. We suggest that an extended longitudinal study will contribute to a better understanding of the relationship between the appearance of musculoskeletal findings and growth and development in school children. Accordingly, further analysis of the various stages of growth and development are needed.

Background/Objective Muscle soreness and damage occurs after completing a full marathon. Here we refer to muscle soreness induced by prolonged running as early-onset muscle soreness (EOMS) because muscle soreness and damage markers induced after prolonged running are different from delayed-onset muscle soreness (DOMS) and muscle damage markers induced after eccentric contraction, such as resistance exercise. The dynamics and relationship between muscle damage markers and EOMS are unclear; therefore, in this study, we aimed to elucidate the relationship between EOMS and indirect muscle damage markers, and their dynamics after a full marathon. Methods The following measurements were performed in 19 subjects who completed a full marathon: perceived muscle soreness (using a numeric rating scale), thigh circumference (CIR), hip joint range of motion (ROM), jump height (JH) and muscle damage marker activities in the blood (CK, AST, LDH, ALD) before (Pre), after (Post) and every day for 4 days after a full marathon (D1−4). Results EOMS was induced, as determined by the numeric rating scale score peaking immediately after a full marathon. ROM and JH significantly decreased and all muscle damage markers significantly increased after a full marathon. Serum CK and AST peaked at D1. Serum LDH and ALD peaked at Post and D3. Each marker showed different dynamics. CIR significantly decreased after a full marathon. Conclusion Muscle soreness peaked and muscle damage markers in the blood showed different dynamics after a full marathon. In other words, this is different from DOMS.

Background A forefoot strike (FFS) could be a safer landing technique than a rearfoot strike (RFS) during a cutting motion to prevent anterior cruciate ligament (ACL) injury. Purpose This study aimed to determine the joint angles, ground reaction force (GRF), and muscle activity levels associated with FFS and RFS landings during 180° turns. Study design Cross-sectional study Methods Fourteen male soccer players from the University of Tsukuba football (soccer) club participated in this study. The FFS consisted of initial contact with the toes on the force plates followed by the rearfoot; meanwhile, the initial contact was performed with the heels on the force plates followed by the forefoot for the RFS. Ankle, knee, and hip joint angles were recorded using a three-dimensional motion capture system. GRFs were measured using a force plate. Gluteus medius (GM), rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), semitendinosus (ST), biceps femoris (BF), tibialis anterior (TA), and lateral gastrocnemius (GL) activities were measured by electromyography. Results The activities of GM, GL, and ST from initial contact to early periods during landing into the ground with the FFS are larger than those with RFS. In addition, the results showed significant differences in lower-limb angles and GRFs between the FFS and RFS. Conclusion These results suggest that there might be differences in ACL injury risk during a 180° turn between the FFS and the RFS pattern. An investigation into the grounding method that prevents injury is necessary in future studies. Levels of Evidence Level 3b

Background Increased strain of the iliotibial band (ITB) is a plausible contributing factor for the development of iliotibial band syndrome (ITBS). Although several studies have found relationships between the strain of the ITB and kinematic factors during running, the associations of the ITB strain with knee alignment and sex, which are considered intrinsic factors, are not well understood. Objective To clarify the sex differences in the ITB strain between genu varum and normal knee alignments in different postures. Design Observational cross-sectional study. Setting Laboratory research within a university. Participants Forty-four healthy recreational athletes (21 men and 23 women) volunteered for this study and were divided into four groups by sex and knee alignment: men with genu varum alignment, men with normal knee alignment, women with genu varum alignment, and women with normal knee alignment. Methods An ultrasound real-time elastography (RTE) unit was used for distal ITB strain measurements in weight bearing and for different non-weight-bearing: neutral, knee flexion, hip adduction, and hip adduction with knee flexion. Gender information and the intercondylar distance data were collected to divide the participants into two groups. Main outcome measurements Main Outcome was the ITB strain (strain ratio) measured by the RTE. Results There were no significant differences in neutral and hip adduction postures among the four groups. However, during weight-bearing, the women's genu varum group (6.91 ± 1.69; Mean ± SD) exhibited greater strain than both the men's normal group (3.50 ± 1.04, P = .005) and the women's normal group (4.42 ± 1.42, P = .048). In addition, there were significant positive correlations between the intercondylar distance and the ITB strain during weight-bearing (r = 0.315, P = .037). Conclusions The women's genu varum group exhibited a higher ITB strain during weight-bearing, which may be related to the high incidence of ITBS in women athletes. Furthermore, the changes in alignment and muscle activities during weight-bearing could influence the strain of the ITB. Level of evidence III.

The purpose of this study was to determine the factors related to the occurrence of concussion in rugby tacklers. Match video records showing tackles leading to concussion were used to identify injury-inciting events. Additionally, noninjury tackles by concussed tacklers (prior to concussion) and position-matched tacklers from the same matches were used as a control cohort. All tackles were coded according to the tackling characteristics. The odds ratio (OR) was reported by logistic regression. The results demonstrated that a side step of the ball-carrier reduced the risk of concussion for tacklers (OR = 0.13 [95% CI, 0.03-0.58]; P = .008). Conversely, the tackler's head/neck contacting the ball-carrier (OR = 18.62 [95% CI, 4.59-75.49]; P < .001) and not remaining bound to the ball-carrier since making initial contact (OR = 4.38 [95% CI, 1.69-11.34]; P = .002) were identified as risk factors for the concussion of tacklers. These results suggest that avoidance movements of the ball-carrier prior to tackling reduced the risk of concussion and that incorrect tackling techniques contributed to an increased occurrence of concussion. Furthermore, the probability of concussion for tacklers increased when their head was in front or to one side of the ball-carrier, and the direction of the tackle also affected the risk of concussion, especially from the side. Therefore, it is important to emphasize the tackler's head position in conjunction with the direction of tackle.

Background: High-intensity exercise affects the level of salivary nitric oxide (NO) with an impact on oxidative stress such as a reactive nitrogen-oxide species. However, in athletes with high-intensity training, the relationship between salivary NO levels and oxidative stress is yet to be clear. Additionally, the association of salivary NO levels and the common health disorders of athletes is unknown. Thus, the aim of this cross-sectional study was to clarify the relationship between salivary NO levels and oxidative stress, and the health/medical disorders existing in elite class university athletes. Methods: In 250 athletes (males, 151 and females, 99) from undergraduate levels of Japanese University, we investigated the relationship between levels of salivary NO and oxidative stress markers: derived reactive oxygen species (d-ROMs) and biological antioxidant potential (BAP), and also examined that whether salivary NO levels are associated with diseases. Results: There were no significant association between the levels of salivary NO and oxidative stress markers (such as d-ROM and BAP). From the questionnaire, asthma was the most prevalent as evident from medical history of the athletes. Additionally, the salivary NO levels were higher (520 ± 43 µmol/L vs. 375 ± 13 µmol/L, P < 0.05) in the asthma group (n = 9) than in the non-asthma group (n = 241). We determined the optimal cut-off value (P = 0.019) of the salivary NO levels for asthma was 425 µmol/L, with a sensitivity of 88.9% and specificity of 61.8% (area under the curve (AUC), 0.73). Conclusions: Our results suggest that the high levels of salivary NO in trained university athletes in Japan may potentially predict asthma. And this salivary NO level is not associated with markers of oxidative stress and existing diseases in athletes studied here. J Clin Med Res. 2019;11(2):114-120 doi: https://doi.org/10.14740/jocmr3670

The purpose of this study was to analyze head impact kinematics at different locations of Japanese university American football players using a 6DOF (degrees of freedom) device. The subjects of this study were 43 players who belonged to T University in the Kanto Collegiate American Football Association second division. We used a Vector Mouthguard (i1 Biometrics Inc.) equipped with a 6DOF to measure the head LA (linear acceleration), AA (angular acceleration) and AV (angular velocity), as well as the number of head impacts during collisions, and evaluated 4 impact locations (front, side, back, and top) in detail. The total number of head impacts was 2,070 during games and 10,007 during practice sessions for a total of 7 games and 41 practices during fall regular seasons over a 2-year period. The most common head impact location was the front (43.5%), followed by the side (41.9%), top (10.9%), and back (3.7%). When classifying the total number of head impacts at these locations according to player position, skill players showed the highest proportion of side impacts (p < 0.05), whereas linemen showed the highest proportion of frontal impacts (p < 0.05) compared to the other locations. These results support previous studies conducted for university American football players in the United States. That is, the frequency and location of head impacts is greatly influenced by player position. Regarding the magnitude of head impact locations, the LA and AA values for back of the head impacts were the highest both at games and practice sessions. In addition, the AA value for impacts to the top of the head was much higher than the AA value for impacts to the front and side (p < 0.05). Also, there were significant positive correlations between peak LA and peak AA at all head impact locations for games and practice sessions based on player position (p < 0.05). Skill players showed significant positive correlations between peak AA and peak AV at all head impact locations in games (p < 0.05). In comparison, linemen showed significant positive correlations between peak AA and peak AV for frontal and side impacts for games and frontal, side, and top of head impacts in practice sessions (p < 0.05). As a result, it was clear that Japanese university American football players could not stabilize the head during collisions. In conclusion, it was found that the frequency of head impact locations in Japanese university American football players was the same as that in the USA. In head impact kinematics during collisions, Japanese university American football players showed different characteristics from their American counterparts. In the future, we should take into account neck muscular strength and motion analysis to better understand the influence of head impacts on Japanese university American football players.

Objectives: The purpose of this study was to evaluate the relationship between exercise time and musculoskeletal problems and to determine the appropriate amount of exercise for children in both lower- and higher-grade levels of elementary and junior high schools. Materials and Methods: Mark-sheet-type questionnaires were distributed to and collected from all elementary and junior high schools in two cities. We collected 22,494 questionnaires in total. The relationship between exercise time and musculoskeletal problems was analyzed. The χ2 test and multivariate logistic regression analysis were used for statistical analyses. Results: The mean exercise time in school, in addition to physical education time, was 3.1 hours per week. In 56% of the children, the exercise time was less than 2 hours per week, and in 13% of the children, the exercise time was more than 10 hours per week. Although the rate of sports injury increased with an increase in exercise time, the duration of one-leg stand (a test of balance and muscle strength) also increased with an increase in exercise time. The cut-off values for sports injuries in boys/girls were 2.9/2.9 hours, 4.0/2.9 hours, and 7.5/4.2 hours in lower grade elementary school, higher grade elementary school, and junior high school, respectively. Conclusions: Although an appropriate amount of exercise improves one’s physical health and ability, excessive exercise leads to musculoskeletal problems. Approximately 7 hours/week of exercise is recommended for junior high school students. In elementary school, the exercise time should be carefully decided as the musculoskeletal system of the students is still immature.

Background: Neurocognitive function may be a risk factor for anterior cruciate ligament (ACL) injury by changing neuromuscular control such as muscle activities. However, the effect of differences in neurocognitive function on biomechanics and neuromuscular control related to ACL injury risk is not clear. The purpose of this study was to examine the effect of differences in neurocognitive function on biomechanics and neuromuscular control during an unanticipated side-step cutting motion. Method: The subjects were 15 collegiate female athletes who were divided into two groups using the Symbol Digit Modalities Test (SDMT). The experimental task was an unanticipated side-step cutting motion from a 30 cm high box. We calculated joint angles and moments using a 3-dimensional motion analysis system from the dominant leg, and measured muscle activities using a surface electromyography. We calculated the co-contraction ratio (CCR) as relative muscle activity of the quadriceps to the hamstring. Results: As a result, subjects with a lower SDMT score had significantly increased quadriceps activity before and after ground contact and decreased CCR only after ground contact. Conclusion: In the lower SDMT score group, the quadriceps showed stronger muscle activity than the hamstring during an unanticipated side-step cutting motion. This dominant quadriceps muscle activity has been reported to increase the load on the ACL, and there was a possibility of increasing the risk of the ACL injury. Considering these factors, subjects with lower neurocognitive function could have a high risk of ACL injury due to alterations in muscle activities surrounding the knee.

This study aimed to examine lower limb kinematics during a side-cutting task in male collegiate soccer athletes with severe ankle laxity. Forty-seven participants with a history of ankle sprains and perceived ankle instability were categorized into non-laxity (n = 17), laxity (n = 19), and severe laxity (n = 11) groups using stress radiography tests. Three-dimensional kinematic data during the stance phase of a 45° side-cutting task were analysed. The frontal plane kinematics of the knee significantly differed between the three groups (p 0.05). The severe laxity group exhibited a greater abduction angle than the non-laxity group (p 0.05). The horizontal and sagittal plane kinematics of the rearfoot differed between the three groups during the end of the stance phase (p 0.05). Our data suggest that collegiate soccer athletes with both perceived ankle instability and severe ankle laxity exhibit greater knee abduction movement during a 45° side-cutting task compared to those with only perceived ankle instability.

Background: In Japan, in 2016, the School Health and Safety Act was revised and examination of extremities in addition to scoliosis became mandatory. Musculoskeletal examinations were subsequently started using a mark sheet-type questionnaire. In the present study, we aimed to analyze the relationship between physical findings and musculoskeletal problems and propose a preventive strategy for musculoskeletal injuries. Methods: In 2017, a total of 4,073 elementary and middle school students underwent direct musculoskeletal examination. In a direct examination, the following elements were included: torticollis; scoliosis; stiffness of the shoulder, elbow, hip, knee, and ankle; flexion and extension in standing position; flat foot; hallux valgus; and alignment of the upper and lower extremities. Of the 4,073 students who underwent direct examination in early 2017, only 3,754 were able to complete the mark sheet-type questionnaires in early 2018. A prospective longitudinal analysis of the data gathered was performed. Results: A total of 396 (11%) students had injuries. The ankle sprain/non-ankle sprain group comprised 119 (3%)/3,635 (97%) students, while the fracture/non-fracture group comprised 105 (2.8%)/3,650 (97.2%) students, respectively. Comparing the sprain group with the non-sprain group, ankle stiffness significantly correlated with ankle sprain in the univariable and multivariable analyses. Injuries occurred more frequently among boys, older students, students with stiff bodies, and students who were involved in sports activities of longer duration. Conclusion: Ankle stiffness was assumed to be a risk factor for ankle sprain. Stretching of the ankle might be effective for preventing ankle sprain. However, further interventional studies are needed to confirm this finding.

Purpose:In developmental dysplasia of the hip (DDH), the centers of hip rotation move in the superior and lateral direction. In total hip arthroplasty for such cases, movement of the center of hip rotation is in the inferior and medial direction. It causes an increase in leg length and a decrease in acetabular offset. We therefore evaluated the change of hip offset and leg length before and after surgery with two stems having a high offset option.Patients and Methods:The preoperative diagnosis was secondary osteoarthritis due to DDH excluded Crowe IV. A stem selection was decided based on preoperative two-dimensional templating. Total 55 hips in 50 patients were followed up for minimum 10 years. Pre- and postoperative clinical evaluations were performed using a hip joint function scoring system. Radiographic evaluations were used for offset and leg length measurements and other associated factors.Results:Both stems showed excellent clinical results. A high offset option was used in 60% of all cases. No postoperative dislocations were observed. The biological fixation was stable in all cases. The hip offset was restored without excessive leg lengthening in most cases.Conclusion:Anatomical consistency could be maintained by using a stem which matched geometry of the proximal part and had offset option. These cementless tapered stems having a high offset option are suitable for Crowe I to III hip dysplasia if two-dimensional X-ray templates fit the shape of the proximal femurs. They were associated with excellent clinical results and biological fixation. The offset option may be useful to adjust leg length and offset in DDH patients.

[Purpose] The purpose of this study was to investigate the acute effect of low-intensity eccentric hamstring exercise on peak torque angle, range of motion, and passive stiffness. [Participants and Methods] Fourteen healthy young adults exercised as follows: 1) Under low-intensity eccentric hamstring exercise condition, participants performed a stiff-leg deadlift using a 20-kg barbell, 2) Under control condition with participants seated. The peak torque angle during eccentric knee flexion, hip flexion and knee extension range of motion, passive torque, and passive stiffness were measured before and after two conditions in the dominant leg. [Results] The low-intensity stiff-leg deadlift significantly increased hip flexion and knee extension range of motion and significantly decreased passive stiffness. Although the low-intensity stiff-leg deadlift did not change the peak torque angle, the changes in passive torque and passive stiffness were negatively correlated with the change in peak torque angle. [Conclusion] These results suggest that low-intensity eccentric hamstring exercise enhances flexibility, and a decrease in passive torque and passive stiffness are negatively associated with producing the eccentric peak knee flexion torque at a shorter muscle length.

[Purpose] The aim of this study was to investigate the influence of baseline muscle tendon unit stiffness on static stretching. [Participants and Methods] Eighteen healthy males were divided into two groups according to their muscle tendon unit stiffness as follows: High (n=9) and Low (n=9). Flexibility assessment was performed before and after 10 minutes of static stretching. Alterations in range of motion, passive torque at the terminal range of motion, muscle tendon unit stiffness, muscle tendon junction displacement, and tendon length were examined. [Results] No significant interactions were found in all the measurements. After static stretching, the range of motion, passive torque, muscle tendon junction displacement, and tendon length increased, while muscle tendon unit stiffness decreased. There were significant differences in range of motion, muscle tendon unit stiffness, and muscle tendon junction displacement between the groups. [Conclusion] Ten minutes of static stretching increased the range of motion through a decrease in muscle tendon unit stiffness and an increase in tolerance in both groups. Differences in muscle tendon unit stiffness and muscle tendon junction displacement caused the differences in range of motion. Baseline muscle tendon unit stiffness had no effects on static stretching.

Eicosapentaenoic acid (EPA) is an omega-3 polyunsaturated fatty acid that is abundant in fish oil, and has anti-inflammatory or anti-obesity effects. However, the effects of EPA supplementation on mitochondrial content and dynamics (fusion and fission) in skeletal muscle has not been elucidated. We investigated the effects of EPA intake for 4 weeks on denervation-induced mitochondrial adaptation in mice skeletal muscle. ICR mice (male, 8 weeks old) were daily administrated olive oil (control) or EPA at a dose of 300 mg/kg body weight by gavage for 4 weeks. After 2 weeks of oil intake, mice underwent unilateral sciatic nerve transection surgery. The hindlimb without surgery served as the sham-operated control. Body and skeletal muscle weights did not differ between the control and the EPA groups. Peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) and oxidative phosphorylation (OXPHOS) proteins were significantly decreased by denervation surgery. Denervation also induced the reduction of mitochondrial fusion molecules and the increase of mitochondrial fission molecules. Expression levels of PGC-1α and mitochondrial respiration protein MTCO1 were higher in the EPA group than in the control (olive oil) group. In addition, the EPA group contained higher levels of mitochondrial fusion protein OPA1. Our results suggest that EPA intake prevents the reduction of mitochondrial content and fusion proteins in denervated skeletal muscle.

The objective of this study was to examine the effect of sleep on the acquisition of motor skills in young badminton players. Thirteen badminton players, aged 6–9 years (8.0 ± 0.3 years; mean ± SE), practiced the shuttle bouncing drill, and a skill none of the players had prior experience with. After practice sessions, shuttle bouncing performance was immediately tested and then retested 1 week later. We evaluated sleep parameters for 7 consecutive days using actigraphy. Using the median value of sleep efficiency, subjects were divided into two groups: good sleepers and poor sleepers. Good sleepers had shorter sleep latency (p

Background: The use of prophylactic contralateral pinning for slipped capital femoral epiphysis (SCFE) remains controversial. This study evaluated the outcome of SCFE treatment and examined the use of prophylactic pinning. Methods: The study included 44 patients (33 men, 11 women; 54 hips [right, 31; left, 23]), with mean age of 12.9 (7.3-29) years, who underwent treatment between 1986 and 2017, with follow-up for more than 6 months. Patients were divided into 3 groups: group 1 had bilateral SCFE at first presentation, group 2 developed contralateral side SCFE during follow-up, and group 3 had unilateral SCFE until final follow-up. Three patients who received prophylactic pinning were excluded. Univariate and multivariate logistic analyses were performed. Results: Overall, 93% (50/54) of hips underwent positional reduction and in situ fixation and 7.4% (4/54) underwent open reduction. Mean follow-up period was 4.8 (0.5-25) years. Groups 1, 2, and 3 had 7, 3, and 31 cases, respectively. Sex, age, and follow-up period showed no significant differences among the groups. The Rohrer index was significantly higher in group 1, the affected side posterior sloping angle (PSA) was significantly higher in group 3, and the contralateral side PSA and percentage with endocrinopathy were significantly higher in group 2. In multivariate logistic analysis, age, sex, Rohrer index, affected side PSA, and endocrinopathy were significantly correlated with bilateral SCFE. Conclusion: We recommend prophylactic contralateral side pinning in patients with risk factors of obesity, high PSA before slipping, and endocrinopathy. Careful observation until growth plate closure is required in patients without risk factors.