Imaging of muscle activity-induced morphometric changes in fibril network of myofascia by two-photon microscopy.

Myofascia, deep fascia enveloping skeletal muscles, consists of abundant collagen and elastin fibres that play a key role in the transmission of muscular forces. However, understanding of biomechanical dynamics in myofascia remains very limited due to less quantitative and relevant approaches for in vivo examination. The purpose of this study was to evaluate the myofascial fibril structure by means of a quantitative approach using two-photon microscopy (TPM) imaging in combination with intravital staining of Evans blue dye (EBD), a far-red fluorescence dye, which potentially labels elastin. With focus on myofascia of the tibial anterior (TA) muscle, the fibril structure intravitally stained with EBD was observed at the depth level of collagen fibrous membrane above the muscle belly. The EBD-labelled fibril structure and orientation in myofascia indicated biomechanical responses to muscle activity and ageing. The orientation histograms of EBD-labelled fibrils were significantly modified depending upon the intensity of muscle activity and ageing. Moreover, the density of EBD-labelled fibrils in myofascia decreased with habitual exercise but increased with muscle immobilization or ageing. In particular, the diameter of EBD-labelled fibrils in aged mice was significantly higher. The orientation histograms of EBD-labelled fibrils after habitual exercise, muscle immobilization and ageing showed significant differences compared to control. Indeed, the histograms in bilateral TA myofascia of exercise mice made simple waveforms without multiple sharp peaks, whilst muscular immobilization or ageing significantly shifted a histogram with sustaining multiple sharp peaks. Therefore, the dynamics of fibre network with EBD fluorescence in response to the biomechanical environment possibly indicate functional tissue adaptation in myofascia. Furthermore, on the basis of the knowledge that neutrophil recruitment occurs locally in working muscles, we suggested the unique reconstruction mechanism involving neutrophilic elastase in the myofascial fibril structure. In addition to the elastolytic susceptibility of EBD-labelled fibrils, distinct immunoreactivities and activities of neutrophil elastase in the myofascia were observed after electric pulse stimulation-induced muscle contraction for 15 min. Our findings of EBD-labelled fibril dynamics in myofascia through quantitative approach using TPM imaging and intravital fluorescence labelling potentially brings new insights to examine muscle physiology and pathology.

Contracted joint capsule affects labral and chondral lesions in patients with frozen shoulder.

PURPOSE: Intra-articular pathologies, such as labral and chondral lesions, are common in patients with frozen shoulder. This study evaluated the correlations between the range of motion and labral and chondral lesions in patients with frozen shoulder and investigated their pathophysiologies. METHODS: In total, 125 individuals (53 men and 72 women) who underwent arthroscopic pan-capsular release between 2014 and 2020 were included in the study. The range of motion was measured using scapular fixation and true glenohumeral motion under general anaesthesia. The American Shoulder and Elbow Surgeons Shoulder score and the Shoulder Rating Scale score of the University of California, Los Angeles were used to compare intra-articular pathologies. RESULTS: More than 80% of patients with frozen shoulder had labral pathologies, and nearly half of them had chondral pathologies. Labral lesions extending to the anterior rim of the glenoid had a greater range of motion and the greatest total American Shoulder and Elbow Surgeons Shoulder score. More severe chondral lesions had a lesser range of motion, but presented the greatest function scores and the lowest strength scores according to the Shoulder Rating Scale of the University of California, Los Angeles. The pain scores of the American Shoulder and Elbow Surgeons Shoulder score and the Shoulder Rating Scale of the University of California, Los Angeles were not correlated with the degree of these pathologies. The traction force affected the labrum during true range of motion, and the compression force occurred on the articular cartilage during internal rotation at 90° of forward flexion during diagnostic arthroscopy. CONCLUSION: Labral and chondral lesions are common in patients with frozen shoulder. Adherence to the capsulolabral complex induced a limited range of motion and labral and chondral pathologies. Diagnostic arthroscopy with motion is an important method of reproducing the pathogenesis of intra-articular structures for patients with frozen shoulder. LEVEL OF EVIDENCE: Level III.

Validation and reliability of a Japanese version of the Shoulder Pain and Disability Index: A cross-sectional study.

BACKGROUND: The Shoulder Pain and Disability Index (SPADI) is a simple disease specific questionnaire that is used to evaluate the impact of shoulder disorders. The purpose of this study was to translate the SPADI into Japanese (SPADI-Jp) and evaluate its reliability and validity in Japanese patients with shoulder disorders. METHODS: Cross-cultural adaptation of the SPADI was performed according to international guidelines. A total of 100 patients with shoulder disorders participated in this study. Each participant was asked to finish the SPADI-Jp, Disability of Arm, Shoulder and Hand (DASH), and the Short-Form 36 (SF-36) at the initial visit. Thirty-four patients repeated the SPADI-Jp to assess the test-retest reliability. The test-retest reliability was quantified using the interclass correlation coefficient (ICC), while Cronbach's alpha was calculated to assess the internal consistency. The construct validity was assessed using Spearman's rank correlation coefficients. RESULTS: Internal consistency in the SPADI-Jp was very high (0.969), as measured by the Cronbach's alpha. The ICC of the SPADI-Jp was 0.930. There was a strong, positive correlation between the DASH and the SPADI-Jp (r = 0.837, p < 0.001). The SPADI-Jp was significantly correlated with most of the SF-36 subscales. The correlations of the SPADI-Jp with physical subscales of the SF-36 were stronger than those with the other subscales. CONCLUSIONS: We demonstrated that the SPADI-Jp is a reliable and valid self-assessment tool. Because cross-cultural adaptation, validation, and reliability of the disease-specific questionnaire for shoulder pain and disability have not been evaluated in Japan, the SPADI-Jp can be useful for evaluating such patients in the Japanese population.

Effects of joint capsular release on range of motion in patients with frozen shoulder.

BACKGROUND: A thickened joint capsule is believed to be one of the most specific manifestations of and the primary restraint against range of motion (ROM) in frozen shoulders. The purpose of this study was to evaluate the relationship among ROMs under general anesthesia before surgery and the effects of each joint capsular release on ROM. METHODS: ROM was measured using a goniometer with scapular fixation. Arthroscopic pan-capsular release was performed with the patient in the beach-chair position in the following order: (1) rotator interval, (2) coracohumeral ligament, (3) superior capsule, (4) middle glenohumeral ligament, (5) anterior inferior glenohumeral ligament, and (6) posterior inferior glenohumeral ligament. ROMs in forward flexion (FF), lateral elevation (LE), external rotation with the arm at the side (ER1), external rotation at 90° of LE (ER2), internal rotation at 90° of LE (IR2), horizontal flexion, external rotation at 90° of FF (ER3), and internal rotation at 90° of FF (IR3) were evaluated before and after each release. RESULTS: A total of 32 consecutive shoulders were included. After each capsular release, the ROM recovered; the final ROM was significantly greater on the affected side than on the unaffected side. Significant correlations were found between FF and LE, FF and ER1, ER1 and ER2, ER1 and ER3, ER2 and ER3, and IR2 and IR3 on both sides, regardless of surgery. CONCLUSION: Each segment of the joint capsule affected ROM in all directions, supporting the need for whole-joint capsular release; ROM was significantly greater on the affected side than on the unaffected side after surgery.

RAGE-dependent NF-kB inflammation processes in the capsule of frozen shoulders.

BACKGROUND: The etiology of frozen shoulder (FS) remains uncertain. Advanced glycation end-products (AGEs) cause the cross-linking and stabilization of collagen and are increased in FS. The purpose of this study was to elucidate the pathogenesis of FS by evaluating the receptor of AGE (RAGE)-dependent pathways. METHODS: Tissue samples of the coracohumeral ligament (CHL) and anterior inferior glenohumeral ligament (IGHL) were collected from 33 patients with FS, with severe stiffness, and 25 with rotator cuff tears (RCTs) as controls. Gene expression levels of RAGE, high-mobility group box 1 (HMGB1), Toll-like receptor 2 (TLR2), TLR4, nuclear factor-kappa B (NF-kB), and cytokines were evaluated using a quantitative real-time polymerase chain reaction. The immunoreactivities of carboxymethyllysine (CML), pentosidine, and RAGE were also evaluated. CML and pentosidine were further evaluated using high-performance liquid chromatography. RESULTS: Gene expression levels of RAGE, HMGB1, TLR2, TLR4, and NF-kB were significantly greater in the CHLs and IGHLs from the FS group than in those from the RCT group. Immunoreactivities of RAGE and CML were stronger in the CHLs and IGHLs from the FS group than in those from the RCT group. Pentosidine was weakly immunostained in the CHLs and IGHLs from the FS group. CML using high-performance liquid chromatography was significantly greater in the CHLs and IGHLs from the FS group than in those from the RCT group. CONCLUSIONS: AGEs and HMGB1 might play important roles in the pathogenesis of FS by binding to RAGE and activating NF-kB signaling pathways. Suppression of these pathways could be a treatment option for FS.

Correlations Between Range of Motion and Elasticity of the Coracohumeral Ligament Evaluated With Shear-Wave Elastography.

CONTEXT: Range of motion (ROM) in the glenohumeral joint decreases with age in healthy subjects; however, the underlying mechanism remains unclear. The process of aging of the joint capsule, including the coracohumeral ligament (CHL), could affect ROM limitation. OBJECTIVE: This study investigated correlations between elasticity of the CHL, evaluated by means of shear-wave elastography, and age, side dominance, and ROM in healthy individuals. DESIGN: Experimental study. SETTING: Laboratory. SUBJECTS: Eighty-four healthy volunteers (39 men and 45 women, mean age: 42.6 y) were included. MAIN OUTCOME MEASURES: Subjects were divided into 3 age groups: younger (20-39 y), middle (40-59 y), and older (≥60 y) age groups. With participants in the supine position, CHL elasticity in both shoulders was evaluated in both neutral and 30° external rotation, with arms at the sides. ROM, including forward flexion, lateral elevation, external rotation, 90° abduction with external rotation, and hand behind the back were measured with participants in the standing position. RESULTS: The CHL elastic modulus was higher in the older group than in the younger group in the neutral (78.4 kPa [SD: 37.1] and 56.6 kPa [SD: 31.7], respectively) and 30° external rotation positions (135.5 kPa [SD: 63.5] and 71.4 kPa [SD: 32.2], respectively). Negative correlations were found between the CHL elastic modulus and ROM in terms of 30° external rotation and both external rotation (R = -.59, P = .02) and 90° abduction with external rotation (R = -.71, P = .003) in the older group, with correlation coefficients increasing with age. CONCLUSIONS: Significant correlations were identified between CHL elasticity and ROM in both external rotation and 90° abduction with external rotation with increasing age. Decreased CHL elasticity was strongly associated with decreased shoulder ROM in middle-aged and older individuals.

Parents' Own Experience of Verbal Abuse Is Associated with their Acceptance of Abuse towards Children from Youth Sports Coaches.

Verbal or physical abuse from coaches has negative effects on young athletes, and the parents of athletes also have an influence on the sports environment. It is therefore important to understand parents' attitudes towards abuse against their children from the coaches. This study aimed to elucidate the characteristics of parents who accept the infliction of verbal or physical abuse on their children from coaches of youth sports teams. A cross-sectional study using self-report questionnaires was conducted with parents of young athletes (n = 6,493). Multivariate logistic regression models were used to assess the factors associated with parents' acceptability of verbal or physical abuse against their children. The proportion of parents who were accepting of verbal or physical abuse was 21.5%. Acceptability of verbal or physical abuse was significantly associated with male (odds ratio: 1.67, 95% confidence interval: 1.43-1.95), younger age (1.24, 1.09-1.41), lower educational attainment (1.32, 1.17-1.50), smoking habits (1.42, 1.23-1.63), experience of playing on a team with high levels of competition during their junior or high school days (1.31, 1.15-1.50), and experience of verbal and physical abuse by their own former coaches (3.59, 3.03-4.26 and 1.17, 1.02-1.35). About 58% and 28% of parents had experienced verbal and physical abuse from their own former coaches, and parents who had experienced verbal abuse themselves were most likely to be accepting of verbal or physical abuse towards their children. Educating parents is considered to be important for preventing and eradicating abuse against young athletes.

Verbal Abuse from Coaches Is Associated with Loss of Motivation for the Present Sport in Young Athletes: A Cross-Sectional Study in Miyagi Prefecture.

Verbal and physical abuse from coaches has negative effects on young athletes. Although the abuse can lead to the athletes' dropping out, no studies have reported on this topic. The purpose of this study was to elucidate the association between experience of verbal or physical abuse from coaches and loss of motivation for the present sport in young athletes. School-aged athletes (age range, 6-15 years, n = 6,791) were assessed using a self-reported questionnaire. Multivariate logistic regression models were used to assess the association between experience of verbal or physical abuse and loss of motivation for the present sport. Variables considered in the models were sex, age, body mass index, presence of bodily pain, team levels, number of training days per week, number of training hours per day on weekdays and weekends, and frequency of participation in games. The prevalence of loss of motivation for the present sport was 8.1%. Experience of verbal or physical abuse was significantly associated with loss of motivation for the present sport and the adjusted odds ratios (95% confidence intervals) were 1.93 (1.54-2.42, p < 0.001) for verbal abuse and 1.76 (1.27-2.42, p = 0.001) for physical abuse. Findings of this study suggest that experience of verbal or physical abuse from coaches is associated with loss of motivation for the present sport. Eradication of verbal and physical abuse from coaches is important for young athletes to continue sport participation.

Knee pain is associated with lower back pain in young baseball players: a cross-sectional study.

PURPOSE: Considerable research has focused on shoulder and elbow injuries among baseball players; however, although lumbar spine and knee injuries are commonly experienced, they are less frequently studied. During common motions in baseball, such as throwing, hitting, and running, energy is transferred from the lower extremities through the lower back to the upper body. Lower extremity pain, as well as lower back pain (LBP), can disrupt the kinematic chain, and it is important to understand the association between lower extremity complaints and LBP. The purpose of this study was to elucidate the association between knee pain and LBP among young baseball players. METHODS: A cross-sectional study was conducted with young baseball players (aged 6-15 years, n = 1,609) using a self-reported questionnaire. Multivariate logistic regression models were used for analyses. Variables considered in the models were sex, age, body mass index, team levels, number of days of training per week, number of hours in practice per day on weekdays and weekend, frequency of participation in games, practice intensity, and player position. RESULTS: The point prevalence of LBP and knee pain was 8.4% and 13.1%, respectively. Knee pain was significantly associated with LBP. Using the absence of knee pain as a reference, the adjusted odds ratio (95% confidence interval) for LBP was 5.83 (3.93-8.65) (p < 0.001) in the presence of knee pain. CONCLUSIONS: Knee pain was associated with LBP among young baseball players. Clinicians should pay attention to knee complaints to prevent and treat LBP among young baseball players. LEVEL OF EVIDENCE: III.

The characteristics of coaches that verbally and physically abuse young baseball players using a self-reported questionnaire.

BACKGROUND: Because the relationship between coaches and athletes is unequal, verbal and physical abuse remains a common problem among sports coaches. We aimed to elucidate the characteristics of baseball coaches who verbally/physically abuse young baseball players. METHODS: A cross-sectional study was conducted on youth sports team coaches in Miyagi prefecture, Japan (n = 380), using a self-reported questionnaire. Multivariate logistic regression models were used for the analyses, evaluating the following variables: sex, age, educational level, smoking habits, years of coaching, level of baseball-playing experience, personal experience with verbal/physical abuse by former coaches, satisfaction with athletes' attitudes, number of athletes on the team, team competition level, awareness of the recommendations of the Japanese Society of Clinical Sports Medicine, limitations in the total pitch count, difficulty in coaching in other positions, number of games per year, and acceptance of former verbal/physical abuse. RESULTS: The prevalence of verbal/physical abuse toward young athletes was 74.5% (n = 283) and 6.6% (n = 25), respectively. Verbal abuse was significantly associated with personal experience of verbal abuse by former coaches (odds ratio [OR]: 2.00, 95% confidence interval [95% CI]: 1.04-3.85), and acceptance of verbal/physical abuse (OR: 2.61, 95% CI: 1.34-5.10). Physical abuse was significantly associated with greater than 10 years of coaching experience (OR: 7.16, 95% CI: 1.36-37.78), personal experience with physical abuse by former coaches (OR: 4.25, 95% CI: 1.23-14.70), and acceptance of verbal/physical abuse (OR: 3.85, 95% CI: 1.51-9.84). CONCLUSIONS: Coaches' experiences with verbal/physical abuse by former coaches negatively affected young athletes. Breaking this cycle is necessary to keep athletes active and interested in playing baseball. LEVEL OF EVIDENCE: Level III.

Involvement of neutrophils and interleukin-18 in nociception in a mouse model of muscle pain.

Muscle pain is a common condition that relates to various pathologies. Muscle overuse induces muscle pain, and neutrophils are key players in pain production. Neutrophils also play a central role in chronic pain by secreting interleukin (IL)-18. The aim of this study was to investigate the involvement of neutrophils and IL-18 in a mouse model of muscle pain. The right hind leg muscles of BALB/c mice were stimulated electrically to induce excessive muscle contraction. The left hind leg muscles were not stimulated. The pressure pain threshold, number of neutrophils, and IL-18 levels were investigated. Furthermore, the effects of the IL-18-binding protein and Brilliant Blue G on pain were investigated. In stimulated muscles, pressure pain thresholds decreased, and neutrophil and IL-18 levels increased compared with that in non-stimulated muscles. The administration of IL-18-binding protein and Brilliant Blue G attenuated hyperalgesia caused by excessive muscle contraction. These results suggest that increased IL-18 secretion from larger numbers of neutrophils elicits mechanical hyperalgesia.

Roles of IL-1α/ß in regeneration of cardiotoxin-injured muscle and satellite cell function.

Skeletal muscle regeneration after injury is a complex process involving interactions between inflammatory microenvironments and satellite cells. Interleukin (IL)-1 is a key mediator of inflammatory responses and exerts pleiotropic impacts on various cell types. Thus, we aimed to investigate the role of IL-1 during skeletal muscle regeneration. We herein show that IL-1α/ß-double knockout (IL-1KO) mice exhibit delayed muscle regeneration after cardiotoxin (CTX) injection, characterized by delayed infiltrations of immune cells accompanied by suppressed local production of proinflammatory factors including IL-6 and delayed increase of paired box 7 (PAX7)-positive satellite cells postinjury compared with those of wild-type (WT) mice. A series of in vitro experiments using satellite cells obtained from the IL-1KO mice unexpectedly revealed that IL-1KO myoblasts have impairments in terms of both proliferation and differentiation, both of which were reversed by exogenous IL-1ß administration in culture. Intriguingly, the delay in myogenesis was not attributable to the myogenic transcriptional program since MyoD and myogenin were highly upregulated in IL-1KO cells, instead appearing, at least in part, to be due to dysregulation of cellular fusion events, possibly resulting from aberrant actin regulatory systems. We conclude that IL-1 plays a positive role in muscle regeneration by coordinating the initial interactions among inflammatory microenvironments and satellite cells. Our findings also provide compelling evidence that IL-1 is intimately engaged in regulating the fundamental function of myocytes.

Late bedtimes, short sleeping time, and longtime video-game playing are associated with low back pain in school-aged athletes.

PURPOSE: Low back pain is a significant problem for school-aged athletes. Although some risk factors relating to sports activities have been reported, the effect of lifestyles on low back pain in school-aged athletes is not clear. The purpose of this study was to elucidate the association between lifestyles, such as wake-up time, bedtime, sleeping time, and TV-viewing or video-game-playing time per day and low back pain of school-aged athletes. METHODS: A cross-sectional study was conducted with school-aged athletes (aged 6-15 years, n = 6441) using a self-reported questionnaire and multivariate logistic regression models were used for analyses. Variables considered in the models were gender, age, body mass index, team levels, number of days in practice per week, number of hours in practice per day, and lifestyles. RESULTS: The frequency of low back pain was 5.0% (n = 322). Late bedtime, short sleeping time, and long video-game-playing time per day were significantly associated with low back pain. There was no significant association between low back pain and wake-up time or TV-viewing time per day. CONCLUSION: Unhealthy life-style choices, such as late bedtimes, short sleeping time, and longtime video-game playing, were associated with low back pain in school-aged athletes.

Sleep Disturbance Is Associated with New Onset and Continuation of Lower Back Pain: A Longitudinal Study among Survivors of the Great East Japan Earthquake.

Lower back pain (LBP) is a common health problem after natural disasters. Although some related factors have been reported, the effect of sleep disturbances on LBP is not clear. The purpose of this study was to elucidate the influence of sleep disturbances on LBP after the Great East Japan earthquake (GEJE). A panel study was conducted with the survivors of the GEJE (n = 2,295) at three and four years after the disaster using self-reported questionnaires. The changes in the presence of LBP during the two periods were assessed; LBP was characterized as either new onset or continuation of LBP. The participants' sleep conditions were assessed, and the changes in sleep disturbances during the two periods were classified into four groups: absence, new onset, improvement, and continuation. Multivariate logistic regression models were used to analyze the association of the changes in sleep disturbance with new onset and continuation of LBP. The rates of new onset and continuation of LBP were 14.1% and 55.1%, respectively. The changes in sleep disturbances were significantly associated with new-onset and continuing LBP. Using "absence" as a reference for the change of sleep disturbance, the adjusted ORs (95% CI) for new-onset LBP were 2.19 (1.42-3.38) in "new onset," 1.38 (0.83-2.30) in "improvement," and 2.17 (1.50-3.15) in "continuation," and those for continuing LBP were 1.42 (0.71-2.84) in "new onset," 0.98 (0.55-1.74) in "improvement," and 1.60 (1.01-2.51) in "continuation." Careful attention should be paid to sleep disturbances to prevent and improve LBP after natural disasters.

Higher Incidence of Sleep Disturbance among Survivors with Musculoskeletal Pain after the Great East Japan Earthquake: A Prospective Study.

Sleep disturbance is a common symptom after natural disasters. Although musculoskeletal pain also increases after natural disasters, its relation to sleep disturbance is not clear. The purpose of this study was to determine the influence of musculoskeletal pain on new-onset sleep disturbance among survivors after the Great East Japan Earthquake (GEJE). A prospective cohort study was conducted with the survivors of the GEJE at two and three years after the earthquake. New-onset sleep disturbance was defined as sleep disturbance absent at two years and present at three years after the earthquake. The sites of musculoskeletal pain included low back, shoulder, knee, and hand or foot. The number of musculoskeletal pain sites at two years after the earthquake was divided into three categories (0, 1, and 2 or more). Univariate and multivariate logistic regression models were used to calculate the odds ratio (OR) and 95% confidence interval (95%CI) for new-onset sleep disturbance according to the number of musculoskeletal pain sites. A total of 1,102 survivors were included in this study and 14.6% of the participants reported new-onset sleep disturbance. Using "0" as a reference, the adjusted ORs (95% CI) for new-onset sleep disturbance were 2.43 (1.55-3.80) in "1" and 2.96 (1.88-4.64) in "2 or more", respectively (P for trends < 0.001). In conclusion, this is the first study showing higher incidence of sleep disturbance among survivors with musculoskeletal pain after the GEJE. Care for musculoskeletal pain is important to prevent sleep disturbance after natural disasters.

Retained Myogenic Potency of Human Satellite Cells from Torn Rotator Cuff Muscles Despite Fatty Infiltration.

Rotator cuff tears (RCTs) are a common shoulder problem in the elderly that can lead to both muscle atrophy and fatty infiltration due to less physical load. Satellite cells, quiescent cells under the basal lamina of skeletal muscle fibers, play a major role in muscle regeneration. However, the myogenic potency of human satellite cells in muscles with fatty infiltration is unclear due to the difficulty in isolating from small samples, and the mechanism of the progression of fatty infiltration has not been elucidated. The purpose of this study was to analyze the population of myogenic and adipogenic cells in disused supraspinatus (SSP) and intact subscapularis (SSC) muscles of the RCTs from the same patients using fluorescence-activated cell sorting. The microstructure of the muscle with fatty infiltration was observed as a whole mount condition under multi-photon microscopy. Myogenic differentiation potential and gene expression were evaluated in satellite cells. The results showed that the SSP muscle with greater fatty infiltration surrounded by collagen fibers compared with the SSC muscle under multi-photon microscopy. A positive correlation was observed between the ratio of muscle volume to fat volume and the ratio of myogenic precursor to adipogenic precursor. Although no difference was observed in the myogenic potential between the two groups in cell culture, satellite cells in the disused SSP muscle showed higher intrinsic myogenic gene expression than those in the intact SSC muscle. Our results indicate that satellite cells from the disused SSP retain sufficient potential of muscle growth despite the fatty infiltration.

The Characteristics of Coaches that Verbally or Physically Abuse Young Athletes.

Verbal or physical abuse from coaches has a negative impact on young athletes. To prevent abuse against young athletes, it is important to know the characteristics of abusive coaches. This study aimed to elucidate the characteristics of coaches who commit verbal or physical abuse in youth sports teams. A cross-sectional study was conducted with coaches of youth sport teams in Miyagi prefecture, Japan (n = 1,283), using a self-reported questionnaire (response rate was 24.0%). Multivariate logistic regression models were used for analyses. The prevalence of verbal and physical abuse towards young athletes was 64.7% (n = 830) and 6.2% (n = 79), respectively. Verbal abuse was significantly associated with lower educational attainment (odds ratio (OR): 1.32, 95% confidence interval (95% CI): 1.03-1.69), experiences of verbal abuse by own coaches (OR: 1.85, 95% CI: 1.37-2.50), acceptability for verbal or physical abuse (OR: 2.53, 95% CI: 1.82-3.52), and dissatisfaction with athletes' attitude (OR: 1.62, 95% CI: 1.26-2.07). Physical abuse was significantly associated with experiences of physical abuse by respondents' coaches (OR: 2.71, 95% CI: 1.50-4.92), acceptability for verbal or physical abuse (OR: 3.89, 95% CI: 2.39-6.33), and longer experience of coaching in years (OR: 2.45, 95% CI: 1.20-4.98). The results of this study show that coaches who commit verbal or physical abuse had typically experienced abuse from their former coaches, and adopted a similar style. Breaking the negative cycle of verbal and physical abuse is necessary to eliminate the abuse of young athletes.

Excessive game playing is associated with musculoskeletal pain among youth athletes: a cross-sectional study in Miyagi prefecture.

Youth athletes are known to be at high risk of musculoskeletal (MSK) injuries. Children in developed countries are increasingly adopting a sedentary lifestyle. Although some risk factors related to sports activities have been reported, the effect of lifestyle (i.e. screen time behaviour) on MSK pain in youth athletes is not well known. This study aimed to examine the association of game playing and TV viewing with MSK pain among youth athletes. A self-administered questionnaire was mailed to youth athletes belonging to the Miyagi Amateur Sports Association. The final study population included 6,143 youth athletes (male, 71.1%; age range, 6-15 years). Multiple logistic regression analysis was used to examine the association of game playing and TV viewing behaviour with MSK pain. The point prevalence of MSK pain was 25.5%. The longest category of game playing time (≥3 h) was significantly associated with MSK pain as compared with the shortest category (<1 h) (odds ratio, 1.39; 95% confidence interval, 1.12-1.73, p = 0.003). There was no significant association between TV viewing time and MSK pain. These results suggest that game playing time might be an associated factor for MSK pain among youth athletes.

Youth baseball players with elbow and shoulder pain have both low back and knee pain: a cross-sectional study.

PURPOSE: Serious arm injuries in youth baseball players have been increasing. Though a breakage in the kinetic chain could affect arm injuries, an association between arm injuries and insufficient support of the trunk and lower extremities is not well understood. The purpose of this study was to investigate the association of low back and knee pain with elbow and/or shoulder complaints among youth baseball players. METHODS: A self-administered questionnaire and document informed consent were mailed to youth athletes belonging to the Miyagi Amateur Sports Association. Multiple logistic regression analysis was used to examine the association of low back and knee pain with elbow and/or shoulder pain at the time of the questionnaire. Variables considered in the models were as follows: sex, age, BMI, years of athletic experience, position, team level, the amount of practice, participating day in team practice and game per week, frequency of participation in games, and practice intensity. RESULTS: The final study population was comprised 1582 youth baseball players (aged 6-15 years old, male 95.6 %) who had responded to the questionnaire. A total of 24.8 % (n = 381) had elbow and/or shoulder pain, whereas 8.5 % (n = 130) had low back pain and 13.1 % (n = 201) had knee pain. The prevalence of elbow and/or shoulder pain with concomitant low back and knee pain was 61.2 % (n = 82) and 51.9 % (n = 108) (p < 0.001), respectively. The presence of low back and knee pain was significantly associated with the prevalence of elbow and/or shoulder pain among youth baseball players [adjusted odds ratio (ORs): 4.31, 95 % confidence interval (95 % CI): 2.86-6.51, p < 0.001, and ORs: 2.92, 95 % CI: 2.09-4.09, p < 0.001, respectively]. For other variables, older age (10- and 11-year old: ORs: 1.73, 95 % CI 1.10-2.73, p = 0.018; 12-15 year old: ORs: 1.62, 95 % CI: 1.18-2.58, p = 0.006), pitcher (ORs: 1.46, 95 % CI: 1.10-1.94, p = 0.009), catcher (ORs: 1.69, 95 % CI: 1.24-2.31, p = 0.001,), and practice intensity (ORs: 1.58, 95 % CI: 1.22-2.06, p = 0.001) were significantly associated with elbow and/or shoulder pain. CONCLUSION: Both low back and knee pain were significantly associated with elbow and/or shoulder pain in youth baseball players. Clinicians should check the complaints of the trunk and lower extremities as well as those of the elbow and shoulder for preventing severe injuries in youth baseball players. Level of Evidence III.

Comparative proteome analysis of the capsule from patients with frozen shoulder.

BACKGROUND: The etiology of frozen shoulder (FS) is unclear. Accordingly, this study used a label-free quantitative shotgun proteomic approach to elucidate the pathogenesis of FS based on protein expression levels. METHODS: Tissue samples from the rotator interval (RI), middle glenohumeral ligament (MGHL), and anterior-inferior glenohumeral ligament (IGHL) were collected from 12 FSs with severe stiffness and 7 shoulders with a rotator cuff tear (RCT) as controls. Protein mixtures were digested and analyzed by nano-liquid chromatography/electrospray ionization-tandem mass spectrometry. Relative protein expression levels were calculated by the signal intensity of identified peptide ions on mass spectra. Differentially expressed proteins between FS and RCT samples were evaluated by a gene enrichment analysis using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes. RESULTS: We identified 1594 proteins, 1358 of which were expressed in all 6 tissue groups. We detected more upregulated proteins in the upper (RI and MGHL) FS groups and the lower (IGHL) RCT group than in the comparative groups, respectively. Various proteins with functions in tissue repair, collagen metabolism and fibrillation, cell-cell and cell-matrix adhesion, blood coagulation, and the immune response were expressed more highly in the RI and MGHL FS groups than in the RCT group. Proteins with functions in phagocytosis, glutathione metabolism, retinoid metabolism, and cholesterol metabolism were expressed more highly in the IGHL RCT group than in the FS group. CONCLUSIONS: The pathophysiology of FS differs between the upper and lower parts of the joint capsule. Different treatment strategies for FS may be appropriate, depending on the location.