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 Author

Electromyographic and Kinematic Trunk Analysis of Boxing during a Dominate Straight Punch

The purpose of this study was to compare the surface electro myogram of trunk muscle activity and the three-dimensional kinematics of the trunk between experienced and novice boxers during straight punch with the rear arm. Fifteen university-age males participated in the study. Participants were ranked as experienced (n=8) or novice (n=7). The straight punch was broken into three phases as Preliminary Movements (PM), Thrown Punch (TP), and Returned Punch (RP). The surface electro myogram captured the activity of the rectus abdominis, external oblique, deltoid, and rectus femoris on the dominant side and the internal oblique-transversus abdominis (IO-TrA) and multifidus on both sides. Three-dimensional motion analysis was performed to calculate the horizontal angle of the Acromial line, the ASIS line and the Greater Trochanter of the femur (GT) line. Results of the surface electro myogram of the IO-TrA on the non-dominant side of the novice group during the PM phase were significantly higher than those of the experienced (p<0.05). Similarly, the IO-TrA of the dominant side of the novice during the TP phase were significantly higher than that of the experienced (p<0.05). In motion analysis, the ASIS line and the GT line were significantly greater in the experienced group compared with the novice (p<0.05). The novice group did not allow the entire trunk to rotate, but rather twisted the thoracolumbar vertebrae to throw the punch. Trunk rotation, not trunk twist, is important to the execution of the straight punch

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

Cross-cultural adaptation, reliability, and validity of the Japanese version of the Cumberland ankle instability tool

Purpose To study validity and reliability of a Japanese version of the Cumberland Ankle Instability Tool and to determine the optimal cutoff score. Methods In this study, the questionnaire was cross-culturally adapted into Japanese. The psychometric properties tested in the Japanese version of the CAIT were measured for criteria validity, internal consistency and test–retest reliability in 111 collegiate soccer athletes. We also established the questionnaire cutoff score for discriminating between individuals with and without CAI. Results There was a significant correlation between the Japanese version of the CAIT and the Karlsson score (r = 0.604, p < 0.001). The questionnaire had a high internal consistency (Cronbach’s α = 0.833) and reliability [intraclass correlation coefficient (ICC) = 0.826, 95% confidence interval (CI): 0.732–0.888]. The optimal cutoff score was ≤25, which was consistent with previous reports. Conclusions The Japanese version of the CAIT has been shown to be a valid and reliable questionnaire for determining the presence of CAI. We expect that researchers and clinicians will use the Japanese version of the CAIT in Japan

Gender difference in neuromuscular hip and knee joint control during single-leg landing

Background: Female’s altered lower limb control has been considered as a possible factor for their high anterior cruciate ligament injury rate. However, the detailed gender difference in lower limb control during impact activity is not well studied. The purpose of this study was to investigate the gender difference in neuromuscular hip and knee joint control during single-leg landing motion. It was hypothesized that the male and female subjects show different electromyographic activity patterns for controlling hip and knee motion and female characteristics would elevate their risk for anterior cruciate ligament injury. Methods: Ten male and 8 female subjects took part in this study. Electromyographic activities of quadriceps, hamstrings and gluteus medius, and three-dimensional kinematic data of hip and knee were measured during single-leg landing task. Peak activities and timing of peak activities of each muscle were compared between genders. Gender differences in the hip and knee kinematics were also investigated. Results: Female subjects showed significantly greater peak activities in vastus medialis, vastus lateralis and gluteus medius compared to male subjects（p < 0.05）. Semitendinosus and biceps femoris in females peaked significantly earlier compared to male ST, BF and female quadriceps（ST; p < 0.05, BF; p < 0.05）. Female subjects simultaneously exhibited greater knee valgus（p < 0.05） and hip adduction（p < 0.05）. Conclusion: Higher vastus medialis activities found in females were considered a strategy to resist knee valgus motion. However, higher vastus medialis activities may cause tibial anterior shear force but resist knee valgus unless synchronized hamstrings activities. Females showed greater hip adduction despite of high gluteus medius activities. This suggests that hip muscle weakness leads to failed hip control

The external force model for determining the frontal plane knee loading pattern ‒ Implication for the mechanism of non-contact anterior cruciate ligament injury -

This study proposes a simple model for predicting the external knee adduction-abduction moment, which is a key mechanism of anterior cruciate ligament（ ACL） injury. We simplified the Newton-Euler’s equation of motion by omitting its dynamic terms, since the experimental trial revealed that the contribution of the dynamic terms became negligible relative to the external force term during landing impact phase. The experimental data also showed that the external force term precisely predicted the knee adduction-abduction moment which was calculated by the Newton-Euler’s equation of motion. This result means that the knee loading pattern during impact activity is largely determined by the external force and if the lower limb orientation with respect to the ground reaction force（ GRF） is inappropriate, knee would experience a large abduction loading. Next, we estimated GRF and its acting point from the measured kinematic data aimed at predicting knee loads without using a force plate data. The result indicated that the moment calculated by the external force model using estimated GRF broadly predicted the profile of the Newton‒Euler method, but was less precise during impact phase. As an implication for the mechanism of non contact ACL injury, the specific landing motions which can especially increase the knee abduction loading were introduced through model consideration