This study aimed to translate, adapt, and assess the psychometric properties of the Japanese version of the Victorian Institute of Sports Assessment for Patellar Tendinopathy (VISA-P-J). We enrolled 43 participants ≥ 18 years with a history of painful patellar tendon symptoms lasting ≥ 1 month for patellar tendinopathy. We evaluated pain levels during daily activities and sports, symptom classification, and patient global impression of change at baseline, 1 week, and 12 weeks. We assessed the psychometric properties, including reliability, validity, responsiveness, and interpretability, of the VISA-P-J following COSMIN guidelines. The intraclass correlation coefficient for the test-retest reliability of VISA-P-J was 0.87, with a standard error of measurement of 0.89. The Cronbach’s alpha for internal consistency of VISA-P-J was 0.81. Criterion validity showed a correlation between VISAP- J scores and symptom classification, pain during daily life, and pain during sports activities (r=-0.52, r=-0.66, r =-0.86, respectively ; p ＜ 0.01 ) . Construct validity and responsiveness of VISA-P-J were confirmed through hypothesis-testing methods. The minimal clinically important difference for VISA-P-J was determined to be 7 points. This study demonstrates that VISA-P-J is a reliable, valid, and responsive assessment tool for individuals experiencing chronic patellar tendon pain.

This study aimed to investigate changes in bone turnover during a competitive season. Twenty-five of 66 male collegiate long-distance runners were analyzed. They participated in measurements five times a year. Bone turnover markers (bone specific alkaline phosphatase and tartrate-resistant acid phosphatase-5b), sex hormones (free testosterone and luteinizing hormone), and cortisol were measured through blood sample collections; we calculated the uncoupling index from bone formation and resorption markers. Running mileage was calculated as the training volume. Changes in blood values, body composition, and running mileage were analyzed using a mixed model. The relationships between bone turnover markers and training volume were assessed. Results showed that during a competitive season, the bone formation marker level decreased compared to the baseline level, while the bone resorption marker did not change. Moreover, bone turnover markers did not correlate with training volume. Low energy availability was a factor in the change of bone turnover. The present study only focused on energy expenditure. Therefore, it is necessary to assess the relationship between bone metabolism and energy availability.

We included 36 athletes (43 lesions) with rotator cuff muscle (RCM) strain from March 2015 to April 2022. We investigated the number of injuries, injured areas, presence of causal accidents, presence of complications, the classification of Japan Institute of Sports Science, sports events, and causal motions for each RCM strain. In 9 cases of infraspinatus muscle strain, the injured areas were transverse and oblique fibers. There were significantly more cases with no trauma. All athletes had combined injury, most of which were TypeI Grade1. Many patients were overhead athletes. In 18 cases of supraspinatus muscle strain, the injured areas were anterior and posterior fibers, and supraspinous fossa. There was no significant difference in the presence of causal accidents or combined injury, most of which were TypeI Grade1. Many patients were baseball players. In 16 cases of subscapularis muscle strain, the injured areas were upper, upper-to-lower, and middle-to-lower fibers. There was no significant difference in the presence of causal accidents. There were significantly more cases with no combined injury. Many cases were caused by forced shoulder abduction and external rotation. We need to consider that athletes with shoulder pain may have RCM strain.

(Purpose) Ankle sprains are the most common sports injuries, and limited ankle dorsiflexion is related to anterior cruciate ligament (ACL) injury. This study sought to identify differences in lower-extremity kinematics between healthy athletes and athletes having previous ankle sprains and limited ankle dorsiflexion (excluding chronic ankle instability (CAI) ), during landing and stopping tasks. (Methods) Twenty subjects with previous ankle sprains and 18 subjects without were included. In athletes with previous ankle sprains, and limited ankle dorsiflexion (≥5̊) in comparison with the uninjured ankle, but without CAI, the injured ankle was compared to ankles of uninjured athletes. Ankle dorsiflexion strength was measured, and stop and landing tasks were captured using a 2D video camera. Knee, hip, and ankle flexion/dorsiflexion angle at initial contact (IC), 33ms after IC, and maximum knee flexion were calculated. (Results) There were no significant differences in lower-extremity kinematics during landing and stopping tasks between these groups, except for less ankle planter flexion in the ankle-sprain group 33ms after IC (p = 0.015). (Conclusion) Ankle-sprain history necessitates a different ankle movement strategy during stopping tasks. On the other hand, knee and hip flexion angle, which affect the risk of ACL injury, were not significantly different.

The purpose of this study was to examine the injury characteristics in breakdancers by dance style. We conducted a questionnaire survey on 74 breakdancers. The questionnaires consisted of (1) dance style, (2) history of injury, (3) injury sites, and (4) injury situation. The dancers who mainly performed footwork were defined as ‘footwork style dancers’ (S group), and those who mainly performed power moves were defined as ‘power move style dancers’ (P group). The number of dancers in the S and P groups was 38 and 36, respectively. Twenty-eight dancers had a history of injury (66 injuries in total), with a significantly higher proportion in the P group (p=0.04). The P group had a significantly higher proportion of injuries in the upper extremities (p=0.02), shoulder (p=0.02), and wrist (p=0.04). Power moves were the most common injury situation, occurring in 34 of 66 cases. The results of this study suggest that power moves are associated with injuries in the shoulder and wrist joints, where there were more opportunities for support weight.

The purpose of this study was to examine the relationship between quantitative and qualitative indices of rectus femoris muscle and physical function in junior female athletes. We included 18 junior female athletes who participated in the Kyo no Kodomo Diamond Project. Muscle thickness was evaluated as a quantitative index, and muscle intensity was evaluated as a qualitative index of muscle. Standing long jump distance and vertical jump height, as well as grip strength and isometric knee extension torque, were measured. Muscle thickness revealed significant positive correlations with isometric knee extension torque (r=0.86). Muscle intensity demonstrated significant negative correlations with standing long jump distance (r=－0.55) and vertical jump height (r=－0.59). In junior female athletes, qualitative indices of rectus femoris muscle were found to be associated with jump performance. Specifically, muscle thickness and muscle intensity were identified as explanatory variables that may contribute to jump performance.

This study aimed to examine the relationship among traumatic shoulder dislocation, upward scapular rotation angle, thoracic elevation mobility, and trunk muscle endurance in 52 university rugby players. A digital inclinometer was used to determine the angle of scapular upward rotation in the drooping and maximally elevated positions of the upper extremities. The index of thoracic elevation mobility was defined as the upper thoracic motion calculated from frontal radiographs of the upper extremities in the drooped and elevated positions. Trunk muscle endurance was measured using a stopwatch for isometric muscle endurance in flexion, extension, and lateral flexion directions. Each measurement was compared between players with (with-dislocation group) and without (non-dislocation group) a history of traumatic shoulder dislocation. Nine patients had dislocations and 43 did not. Upper thoracic motion was lower in the with-dislocation group than in the non-dislocation group. Therefore, decreased thoracic elevation mobility was suggested to be a physical characteristic of rugby players with a history of traumatic shoulder dislocation.

(Introduction) Although elementary school children with lumbar spondylolysis are often reported to have a low rate of bone healing, there is no consensus on the type of brace used for its treatment. Therefore, we investigated the bone healing rate in elementary school children with lumbar spondylolysis using different types of braces. (Methods) Of the 39 elementary school students diagnosed with lumbar spondylolysis, 32 (51 sites) who were traceable to the end of the follow-up were included. The patients used following 3 types of braces: soft braces (8 sites), semi-rigid braces (18 sites), and rigid braces (25 sites). Bone healing rate were compared retrospectively using the medical records. (Results and Discussion) The bone healing rate for the soft braces, semi-rigid braces, and rigid braces were 25%, 56%, and 76%, respectively. The bone healing rate was significantly higher with the rigid brace compared with the soft braces (p=0.003). There was no significant difference in the bone healing rate between the two groups of soft and semi-rigid braces and semi-rigid and rigid braces. In conclusions, rigid brace should be used in the treatment of lumbar spondylolysis in elementary school children aiming for bone healing.

Recent reports have indicated that hay fever affects over 40% of the Japanese population. When prescribing medication to athletes attention should be paid to prohibited substances in sports. The objective of this study was to investigate hay fever prevalence among athletes to enhance its treatment. A survey was conducted via Google Forms from May to September 2023, focusing on participants from the Japan Rugby League One and top university leagues. The items surveyed included age, athletic history, presence of hay fever and other allergies, treatment modalities, and their effects on rugby performance. The response rate was 33.9%. Participants averaged 21.6±3.8 years in age, and their competition history was 11.8±5.3 years. The prevalence of hay fever was 42.7%, based on medical diagnosis and medications. Of the 750 athletes reporting hay fever symptoms, 77.5% experienced performance hindrance, primarily due to “loss of concentration or discernment due to symptoms” (73.1%). Reports of performance hindrance were significantly more prevalent among athletes receiving medical care from a doctor and who received medications, both prescribed and over the counter, compared to those who were not. These findings highlight the importance of hay fever treatment in rugby players.

This study examined the relationship between position-specific lumbar spondylolysis incidence and physical characteristics based on the results of 12-year medical checkups (MCs) of adolescent baseball players. The participants were 258 junior high school students that were planning to join a high school hardball team. For each MC, we compared players with lumbar spondylolysis (P group) with the other players (N group) overall and by position. Overall, the MC results between the P and N groups were not significantly different. However, the body fat percentage of catchers was 20.2±4.0% and 16.7±4.8% in the P and N groups, respectively. Additionally, the total score of the general joint laxity test (GJL) was 2.3±1.3 points and 1.1±0.8 points in the P and N groups, respectively, with the P group scoring significantly higher. Logistic regression analysis showed that body fat percentage (p＜0.05) and GJL (p＜0.01) remained independent risk factors for the P group. Additionally, the body fat percentage and GJL score for catchers were both higher in the P group than in the N group. Thus, the results of MC in adolescent baseball players demonstrated an association between physical characteristics and findings of lumbar spondylolysis incidence in catchers.

(Patients) 47 cases and 49 feet diagnosed with navicular stress fractures were examined at our hospital from April 2012 to December 2022 (23 cases and 25 feet in males, 24 cases and 24 feet in females). (Methods) Based on McKeon et al.’s report, we categorized cases into five groups based on avascular regions: dorsal foot, dorsal to lateral body, central, plantar, and unclassifiable. We investigated the relationship between the fracture sites/fracture types and the avascular regions. (Results) Regarding the fracture sites, the lateral side of the body accounted for the highest percentage at 57.1% overall, and this pattern was predominant in both males and females. For fracture types, Type 0.5 was unclassifiable in all cases, while Type I fractures were more common on the dorsal region in males and the lateral side of the body in females. Both Type II and Type III fractures were more prevalent on the lateral side of the body in both males and females. (Conclusions) The presence of avascular regions, especially on the dorsal region and lateral body, is considered to play a role in the progression of navicular stress fractures. This suggests that it may be one of the causes of the refractory.

(Background) To prevent anterior cruciate ligament (ACL) injuries, it is important to prevent the knee from moving inward (knee-in), which is a dangerous position during landing, is important. Therefore, we developed the unilateral elastomeric strap (UES) using elastic materials. This study aimed to clarify the control effect of UES on knee-in by three-dimensional analysis of during landing. (Participants and Methods) The participants were 25 female university students (19.6±0.7 years) with marked knee-in tendency. They performed a one-leg landing from a 30-cm platform, with a one-sided spiral-shaped UES, approximating the running of the gluteus maximus and sartorius muscles, was placed on a compression wear (UES [+]) and UES (－) was placed on the CW. Three successful trials were selected for analysis. The hip joint angles (flexion, abduction, internal rotation) and knee joint angles (flexion, valgus) were calculated using a threedimensional motion analyzer, and the results were compared. Statistical processing was performed using a paired t-test with 5% significance level. (Results) UES (+) significantly to preventing decreased hip internal rotation before landing, hip adduction and internal rotation angle from 0ms to 80ms after landing, and knee valgus. (Conclusion) UES suppressed hip adduction, internal rotation, and knee valgus at landing.

The purpose of this study was to investigate stress fractures in female athletes who belongs to Japan Association for University Athletics and Sport (UNIVAS). A web-based survey was conducted between June 2022 and August 2023, with a total of 4,053 female athletes responding. The results showed that 3.1% (126) of athletes reported a total of 140 stress fractures during the year. The most common fracture sites were on foot and toe (32.1%) and lower leg (22.1%), highlighting a tendency for fractures to occur in the distal region. The track and field had the highest frequency rate of stress fractures (19.0%). Multivariate logistic analysis identified ‘high volume practice (β=0.5, Exp=1.6)’, ‘lower BMI (β=－0.1, Exp=0.9)’ and ‘higher competition level (β=0.7, Exp=2.1)’ as independent factors for stress fracture. These findings identify the prevalence of stress fractures in female athletes in Japan and the importance of monitoring training intensity, BMI and competition level to reduce such injuries, particularly in sports such as track and field.

This study aimed to prospectively assess the relationship between the results of physical function tests and occurrence of medial elbow injuries in the following year according to grade level during physical examinations in baseball players. The participants were 295 elementary school boys who underwent physical examination as baseball players. The evaluation parameters included the deep squat and one-leg stand tests. The participants were allocated to the good and poor groups based on their test results. Furthermore, the relationship between the results and presence or absence of medial elbow disability in the following year was assessed. Regarding the early grades, significantly more athletes with poor deep squat test scores experienced medial elbow injury in the following year. There were no significant differences between the good and poor groups in terms of the other parameters based on grade. In conclusion, this prospective study indicated that, in the early grades, a poor deep squat test score may be a screening option for predicting the risk of medial elbow injuries such as poor pitching form and conditioning. Since the deep squat test does not require specialized skills, it may be useful for field personnel to assimilate and use this evaluation method.

(Objective) Investigate characteristics of hip adductor muscle strain. (Subjects and Methods) The characteristics of 90 student athletes with 102 injury sites, who were diagnosed by MRI as hip adductor muscles strain were statistically analysed. (Results) Pain was perceived in the groin (40%) and in the medial thigh (29%). Soccer was the most common sport (47%). There were 78 single adductor muscle injuries and 12 multiple adductor muscle injuries. Adductor longus injury was the most common single injury (51). Eleven of the multiple injuries involved the adductor longus. The adductor longus was mostly injured distally and pain was mostly medial of the thigh. There were 43 injuries with no trauma and 47 injuries with trauma. Single adductor longus injury was significantly longer time between pain onset and consultation than the other adductor muscle groups，and no trauma than the other adductor muscle injuries with no trauma (p＜0.01). There was no significant difference in the JISS classification of injury type between the adductor longus and the other adductor muscles with single injury. (Conclusions) Adductor longus injury was the most common single injury, and injury was longer time from pain to presentation and a higher percentage of no trauma cases than other adductor muscle groups.