Taurine supplementation enhances endurance capacity by delaying blood glucose decline during prolonged exercise in rats.

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.

Effects of Active and Passive Warm-ups on Range of Motion, Strength, and Muscle Passive Properties in Ankle Plantarflexor Muscles.

ABSTRACT: Takeuchi, K, Takemura, M, Nakamura, M, Tsukuda, F, and Miyakawa, S. Effects of active and passive warm-ups on range of motion, strength, and muscle passive properties in ankle plantarflexor muscles. J Strength Cond Res 35(1): 141-146, 2021-The purpose of this study was to examine the effects of active and passive warm-ups on flexibility and strength of calf muscles. Fourteen healthy males (age: 23.1 ± 2.6 years, height: 172.7 ± 5.6 cm, and body mass: 64.5 ± 7.0 kg) performed 3 types of warm-ups respectively for 10 minutes in a random order: an active warm-up by pedaling a cycling ergometer, an active warm-up doing repeated isometric contractions, and a passive warm-up in a hot water bath. To assess flexibility, range of motion (ROM) of ankle dorsiflexion, passive torque of ankle plantarflexion, and muscle tendon junction (MTJ) displacement were measured and then muscle tendon unit (MTU) stiffness was calculated. After the flexibility assessment, peak torque during maximum voluntary isometric contraction was measured to assess the isometric strength. These data were compared before and after each warm-up. As a result, all 3 types of warm-ups increased ROM (p < 0.05) and passive torque at terminal ROM (p < 0.01), but there were no significant changes in MTU stiffness or MTJ displacement. The active warm-up by pedaling a cycling ergometer increased peak torque during isometric contraction (p < 0.05), whereas the other warm-ups did not show significant alterations. In conclusion, the active warm-up with aerobic exercise increased flexibility and strength of the calf muscles.

Male collegiate soccer athletes with severe ankle laxity display increased knee abduction during side-cutting tasks compared to those with only perceived ankle instability.

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.

Chronological changes in neuromuscular cooperativeness before and after muscle fatigue loading using the silent period of the quadriceps and hamstrings in young female athletes.

[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.

Characteristics and factors of concussion events for tacklers in collegiate rugby union.

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.

Relationship between early-onset muscle soreness and indirect muscle damage markers and their dynamics after a full marathon.

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.

Screening for musculoskeletal problems in children using a questionnaire.

BACKGROUND: On April 1, 2016, the Ministerial ordinance was enforced, and musculoskeletal examination of the extremities was made mandatory. From 2008, the University of us started musculoskeletal direct examination. To expand the examination, from 2016, we started to use the marksheet-type questionnaire. This study aimed to report the results of a musculoskeletal examination and investigate the association between musculoskeletal examination and age/gender and reports the reliability of the collected questionnaire data. METHODS: Direct musculoskeletal examination was performed in K school by 7 orthopedic surgeons. A marksheet-type screening questionnaire was distributed to all the elementary and junior high school students in Tsukuba and Hitachiomiya cities. The rates of abnormal findings for scoliosis, standing flexion, full squatting with the heels on the floor, general joint laxity, and standing on one leg, torticollis, and flat feet were calculated. We compared the results of the questionnaire and direct examination and calculated sensitivity, specificity, and odds ratio. RESULTS: A total of 1844 students in K school had direct examination, and 22,494 questionnaires were able to correct in Tsukuba and Hitachiomiya cities. The rates of abnormal findings in direct examination/questionnaire in scoliosis, standing flexion, full squat, general joint laxity, standing on one leg, torticollis and flat foot were 18.7% (344/1842)/5.1% (1094/21441), 20.2% (372/1841)/26.6% (5817/22078), 6.2% (114/1832)/6.9% (1516/22101), 7.5% (1648/22252), 4.9% (1100/22077), 2.2% (31/1844)/1.2% (272/21687), and 12.5% (231/1842)/8.7% (1785/20871), respectively. Sensitivities of the questionnaire for scoliosis, stand flexion, full squatting, torticollis, and flat feet were 16.8% (53/316), 67.9% (250/368), 48.2% (55/114), 18.9% (7/37), and 32.2% (65/202), respectively. CONCLUSION: We reported the result of musculoskeletal examination. Accuracy and reliability of this questionnaire were not satisfactory. To perform high quality musculoskeletal examinations, we will aim to increase the quality of screening methods.

Effect of a leucine-enriched essential amino acids mixture on muscle recovery.

[Purpose] The aim of this study was to determine whether the consumption of a leucine-enriched essential amino acid mixture (LEAA), which is known to increase protein synthesis in muscles, alleviates muscle damage and accelerates recovery by ameliorating muscle damage. [Participants and Methods] A double-blind, randomized crossover trial was conducted over a 5-week period. Ten untrained males (age, 23.0 ± 1.6 years) were asked to repeatedly flex and extend their elbows for 10 counts/set × 5 sets at full power while using a dynamometer. The participants took 3.6-g supplements (LEAA mixture or placebo) 3 times daily on day 0 and for the next 7 days. Changes in serum creatine phosphokinase (CPK) activity and myoglobin concentration as markers of muscle tissue damage were evaluated prior to and after exercise and on days 1, 2, 3, 5, and 7. [Results] The relative ratio of the changes in peak serum CPK activity measured on day 5 was significantly lower after taking LEAA than after taking the placebo. [Conclusion] LEAA consumption suppressed exercise-induced elevation of muscle damage markers in blood, which suggests that LEAA could attenuate muscle damage and aid muscle recovery.

Effect of change in passive stiffness following low-intensity eccentric hamstring exercise on peak torque angle.

[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.

Baseline muscle tendon unit stiffness does not affect static stretching of the ankle plantar flexor muscles.

[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.

The 21- to 27-year results of the Harris-Galante cementless total hip arthroplasty.

BACKGROUND: The Harris-Galante total hip arthroplasty (THA) is a first-generation cementless THA with a porous coating for biological fixation of the implant. Many studies report excellent long-term results for the acetabular cup, but few long-term studies exist for the femoral stem because of relatively poor short-term and midterm results. Here we present the 21- to 27-year results of the cup and the stem of the Harris-Galante THA. METHODS: From 1985 to 1991, 102 Harris-Galante THAs were inserted in 82 patients. At the time of the THA, the mean patient age was 54 years (range, 20-78 years). The primary diagnosis was secondary osteoarthritis due to developmental hip dysplasia (69 [68%] hips). The Japanese Orthopaedic Association (JOA) hip score and thigh pain were measures of clinical outcome. Radiographic review was performed retrospectively. Implant survival was evaluated by Kaplan-Meier analysis. RESULTS: Of 102 hips, 35 hips were from 31 deceased patients, 5 patients (6 hips) were lost to follow-up, 12 hips were revised, and 49 hips were from patients living at the latest follow-up. Among the living patients, 36 hips had a clinical evaluation and 42 hips had a radiograph obtained more than 21 years. The JOA hip score improved from 42 points preoperatively to 83.5 points at the latest follow-up. Thigh pain was reported in 13 hips. One cup and four stems were loose at the latest radiographic review. Most cup revisions were related to acetabular osteolysis. Fifteen hips showed severe stress shielding. Kaplan-Meier analysis of survivorship with any revision, acetabular reoperation, stem revision, and stem loosening as the end point was 87.0%, 90.3%, 95.7% and 86.4%, respectively, at 24.6 years. CONCLUSIONS: Long-term implant survival and clinical results of the Harris-Galante THA were good. Acetabular osteolysis-related cup loosening was a problem of the cup. Loosening, thigh pain, and stress shielding were problems of the stem.

Effects of hyperbaric oxygen on muscle fatigue after maximal intermittent plantar flexion exercise.

The purpose of this study was to investigate the effects of hyperbaric oxygen (HBO) treatment on muscle fatigue after maximal intermittent plantar flexion exercise. Twenty healthy male volunteers (aged from 21 to 24 years) were randomly assigned to either HBO or normoxic group and were blinded to their treatment and group assignment. The HBO group breathed 100% oxygen under 2.5 atmosphere absolute (ATA) for 60 minutes, whereas the normoxic group breathed room air under 1.2 ATA for 70 minutes. The subjects performed a fatigue test, which consisted of 50 maximal unilateral isometric plantar flexions, before and after intervention. Surface electromyography was recorded from triceps surae muscle. Subjects performed maximal voluntary contractions of isometric plantar flexions, and voluntary activation and twitch contractile properties were evaluated with cutaneous tibial nerve stimuli before and after intervention. Compared with initial values during repetitions 4-10, the plantar flexion torque during repetitions 41-50 decreased to 88.5 and 83.2% after HBO and normoxic treatment, respectively. A smaller decrease in muscle force was observed in the HBO group compared with the normoxic group. No differences in function between treatment groups were observed after nerve stimulation. These results suggest that HBO contributes to sustained force production due to suppressing the muscle fatigue progression. In practice, HBO can contribute to the prevention of excess fatigue of agonist muscles for specific exercises involving repeated jumping.

Critical factors for the prevention of low back pain in elite junior divers.

BACKGROUND/AIM: During competitive diving, divers jump up from 1 to 3 m springboards or 5 to 10 m platforms and dive into the water. The impact forces are very large in the water entry phase, and, as such, microtraumatic injuries are common due to the tremendous physical stress placed on the diver. Low-back pain (LBP) is the most frequently reported symptom in divers. This study aimed to extract possible risk factors related to LBP from physical and technical characteristics in Japanese elite junior divers. METHODS: Eighty-three elite junior divers (42 men and 41 women) in Japan were included in this study. LBP was assessed by a questionnaire, interview and physical examination during a national training camp. Morphological data, physical fitness and diving skills were also evaluated. The factors related to LBP were extracted by using logistic-regression analysis and the forward-selection method (likelihood ratio). RESULTS: A total of 37.3% (31 reports) of back pain occurred in the lumbar region. Shoulder flexibility (OR 0.919; 95% CI 0.851 to 0.992) and age (OR 0.441; 95% CI 0.239 to 0.814) were recognised as factors related to LBP in male-elite junior divers, whereas only age (OR 0.536; 95% CI 0.335 to 0.856) was a factor in female-elite junior divers. CONCLUSIONS: Our results suggest that shoulder flexibility is important for preventing LBP in elite-male junior divers, since they require full shoulder flexion during the water entry phase. Limited shoulder flexibility could cause lumbar hyperextension when adjusting for the angle of water entry.

Analysis of trunk rotation during baseball batting with lumbar disc degeneration.

Lower back pain (LBP) is common among baseball players, and the occurrence of lumbar intervertebral disc degeneration is high. The dynamic load on the lumbar spine due to the postures and movements characteristic of baseball is suspected of aggravating LBP caused by degeneration, but the difference in batting action between players with and without degeneration is not known. The purpose of this study was to investigate the difference in batting motion in the presence and absence of lumbar disc degeneration (LDD). The subjects were 18 male baseball players belonging to the University League Division I: seven with disc degeneration and 11 without. The motion task analyzed tee batting. The items examined were the angles of rotation of shoulder, pelvis, hip, and twisting motion; rotation angular velocity; time to maximum angular velocity; and muscle activity potentials of the bilateral latissimus dorsi, erector spinae, multifidus, external oblique, internal oblique, rectus abdominis, and gluteus medius muscles; at each stage of batting action. There were significant differences between the shoulder and pelvis in rotation angle, time to maximum angular velocity, and muscle activity in the presence and absence of LDD, and in the time to maximum angular velocity between the shoulder and pelvis. We infer that these differences are characteristic of batting motion due to LDD.

Kinematics, Kinetics and Muscle Activity Analysis during Single-leg Drop-jump Landing Followed by an Unanticipated Task: Focusing on Differences in Neurocognitive Function.

Background: Lower neurocognitive function is a risk factor for anterior cruciate ligament (ACL) injury. However, the mechanism by which lower neurocognitive function increases the risk of ACL injury remains unclear. Purpose: To clarify the effect of differences in neurocognitive function on landing mechanics during a single-leg drop-jump landing motion followed by an unanticipated task. Study Design: Cross-sectional study. Methods: Fifteen collegiate female athletes were recruited (20.1 ± 1.3 years, 166.6 ± 7.3 cm, 60.6 ± 6.9 kg) and were divided into two groups (the high-performance (HP) group and the lower-performance (LP) group) using the median Symbol Digit Modalities Test (SDMT) score. Three-dimensional motion analysis was employed for the analysis during the experimental task of a single-leg drop-jump followed by an unanticipated landing task from a 30-cm high box. Joint angular changes of the trunk, pelvis, hip, and knee were calculated within the interval from initial contact (IC) to 40ms. Knee and hip moments were calculated as the maximum values within the interval from IC to 40ms. Surface electromyography data from key muscles were analyzed 50ms before and after IC. Independent t-tests were used to compare the effects of different neurocognitive function on the measurement items. Statistical significance was set at p < 0.05. Results: The SDMT score was significantly higher in HP group (HP: 77.9 ± 5.5; LP: 66.0 ± 3.4; p < 0.001). The LP group had a significantly greater trunk rotation angular change to the stance leg side (HP: 0.4 ± 0.8; LP: 1.2 ± 0.4; p = 0.020). There were no significant differences between the two groups in terms of joint moments, and muscle activities. Conclusion: Differences in neurocognitive function by SDMT were found to be related to differences in motor strategies of the trunk in the horizontal plane. Although trunk motion in the sagittal and frontal planes during single-leg drop-jump landing increases the ACL injury risk by affecting knee joint motion, the effect of trunk motion in the horizontal plane remains unclear. Level of Evidence: 3© The Authors.

Injury Prevalence among Young Elite Baseball Players.

This study aimed to describe the injury profiles of young Korean baseball players according to position and age as the proportion and distribution of injuries based on playing position and age remains unclear. A total of 271 elite youth baseball players aged 8 to 16 years were divided into two groups: elementary school (ES) (n = 135) and middle school (MS) (n = 136). The participants' basic, baseball practice, and injury information were collected. Injuries in the MS group were not limited to the elbow and shoulder, and injury prevalence varied by age group and baseball position. The most injured body region in the ES group was the elbow joint, regardless of the position. In contrast, the most injured body region in the MS group was the lower back, except for infielders whose elbows were the most injured. Additionally, the MS group was more likely to experience injuries to the lower back (OR = 4.27, 95% CI = 2.47-7.40), shoulder (OR = 1.93, 95% CI = 1.08-3.43; p = 0.024), and knee (OR = 2.15, 95% CI = 1.17-3.94; p = 0.012). Our findings indicate that excessive practice and a lack of rest during MS (growth spurt period) can significantly increase the risk of lower back problems in young baseball players.

The effects of using a combination of static stretching and aerobic exercise on muscle tendon unit stiffness and strength in ankle plantar-flexor muscles.

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 (p < 0.05), but muscle tendon unit stiffness decreased significantly for all interventions (p < 0.05). Peak torque of ankle plantar flexion and amplitude of electromyography significantly increased for Interventions 1 and 3 (p < 0.05), while these significantly decreased for Intervention 2 (p < 0.05). These data indicated that range of motion and stretch tolerance were increased, but muscle tendon unit stiffness was decreased regardless of the order of static stretching and aerobic exercise. Aerobic exercise after static stretching increased the peak torque and amplitude of electromyography.

Effect of taurine supplementation on the alterations in amino Acid content in skeletal muscle with exercise in rat.

Taurine included abundantly in skeletal muscle, particularly in the slow-twitch fibers, enhances exercise performance. However, the exact mechanisms for this effect have been unclear. The present study investigated the influence of taurine supplementation on amino acids profile in skeletal muscles as one of mechanisms in the enhancement of exercise performance induced by taurine. In the rats that received taurine solution, amino acids concentrations were comprehensively quantified in two portions with different fiber compositions in the fast-twitch fiber dominant (FFD) gastrocnemius muscle after 2 weeks, and in the gastrocnemius and additional other FFD muscles, liver, and plasma with exhausted exercise after 3 weeks. In the FFD muscles after 2 weeks, a common phenomenon that decreased concentrations of threonine (-16%), serine (-15~-16%), and glycine (-6~-16%) were observed, and they are categorized in the pyruvate precursors for hepatic gluconeogenesis rather than biosynthesis, polar, and side-chain structures. The decreases in the three amino acids were significantly emphasized after an additional week of taurine supplementation in the FFD muscles (p values in three amino acids in these tissues were less than 0.001-0.05), but not in the liver and plasma, accompanied with significantly increase of running time to exhaustion (p <0.05). In contrast, the three amino acids (threonine and serine; p < 0.05, glycine; p < 0.01) and alanine (p < 0.01) in the liver were significantly decreased and increased, respectively, following the exhaustive exercise. In conclusion, the taurine-induced reductions of these amino acids in skeletal muscle might be one of the mechanisms which underpin the enhancement of exercise performance by taurine. Key pointsTaurine ingestion significantly decreased certain amino acids in skeletal muscles accompanied with enhanced exercise performance.The decreased amino acids in common were threonine, serine, and glycine, but not alanine; pyruvate precursor for gluconeogenesis.The alteration of three amino acids in muscles was maintained after exhausted exercise.The muscular alterations of them might be one of taurine-induced roles on exercise performance.

Effect of temporary school closure due to COVID-19 on musculoskeletal function in elementary school children.

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<0.05) and between girls in grades 3 and 4 (P<0.01), but no significant differences in other grades or among boys or girls were observed. Conclusion: Initially, we expected that there would be a difference in the results of functional assessment using standing trunk flexion depending on the period of absence from school. However, the results of this study showed no significant changes in standing trunk flexion. Moreover, since children's musculoskeletal functions may be affected by various factors during the COVID-19 pandemic, they should be carefully monitored in the future.

Differences in Muscle Activities and Kinematics between Forefoot Strike and Rearfoot Strike in the Lower Limb during 180° Turns.

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.