Background:A previous cross-sectional study reported that pathogenic factors associated with Osgood-Schlatter disease (OSD) in adolescent athletes include increased quadriceps muscle tightness, lower leg malalignment, and development of apophysitis in the tibial tuberosity.Purpose:To confirm these pathogenic factors associated with OSD in a longitudinal study with regard to physical function and performance.Study Design:Cohort study; Level of evidence, 2.Methods:In this study, 37 boys (mean age, 10.2 ± 0.4 years) were recruited from 2 soccer teams at an elementary school. This cohort study was conducted over an observation period of 1 year, with measurements recorded at baseline, followed by screening for OSD every 6 months. Variables evaluated at baseline included physical function (morphometry, joint flexibility, and lower extremity alignment), presence of Sever disease, and kicking motion.Results:Pathogenic factors associated with OSD in the support leg of adolescent male soccer players included height, weight, body mass index, quadriceps femoris muscle tightness in the kicking and support legs, and gastrocnemius muscle tightness, soleus muscle tightness, and medial longitudinal arch in the support leg. Additional factors included a diagnosis of Sever disease and distance from the lateral malleolus of the support leg’s fibula to the center of gravity during kicking.Conclusion:The onset of OSD was found to be affected by many factors, including developmental stage, physical attributes, and pre-existing apophysitis. In particular, a diagnosis of Sever disease and backward shifting of the center of gravity during kicking increased the risk of the subsequent onset of OSD, suggesting that these factors are very important as a possible focus for interventions.
OBJECTIVE: The purpose of this study was to clarify the characteristics of abdominal deep muscles in adolescent soccer players. METHODS: Participants were 53 soccer players from junior high school and 14 adult soccer players. The deep abdominal muscles of both sides were imaged by ultrasonography. Abdominal muscles on the dominant leg side were selected as the targets of measurements, and measurements of the transversus abdominis (TrA) and internal oblique (IO) muscle were conducted. The muscle thickness of these muscles was measured at rest and during contraction (while drawing-in of the abdominal wall) and served as the basis for comparing the adolescent and adult players. RESULTS: While no significant inter-group differences were noted in the thickness of the TrA or IO muscle at rest, a significant difference was observed during the drawing-in maneuver. CONCLUSION: The deep abdominal muscles of adolescent soccer players have not likely reached full maturity.
Osgood-Schlatter disease is the most common type of knee joint injury among adolescent male soccer players. To clarify the cause of Osgood-Schlatter disease in adolescent soccer players, we previously measured the position of the center of gravity during the kicking motion. It was revealed that the center of gravity during the kicking motion was backward in soccer players who developed Osgood-Schlatter disease. The purpose of the present study was to develop a taping method (prevention tape) to prevent backward center of gravity during the kicking motion and therefore to prevent the onset of Osgood-Schlatter disease. The participants recruited for this study were 36 boys from two soccer teams of an elementary school, with a mean age of 10.2 ± 0.4 years. The three-dimensional coordinates of the markers were calculated using a three-dimensional video motion analysis system. The center of gravity was measured by Yokoi's method, using body part coefficients. A net was set up 3m away from the ball and 1m above the ground in order to measure the kicking motion. When applying the prevention tape, the patella was pulled downward by the traction force of the tape. We investigated the difference in the position of the center of gravity during kicking motion with or without prevention tape. In adolescent soccer players with prevention tape during the kicking motion, center of gravity changed to be significantly more forward than that in players without prevention tape.
This cross-sectional study aimed to clarify the changes in lifestyle and baseball activity before and during the COVID-19 pandemic among youth baseball players. Participants were 99 youth baseball players (ages 9.6 ± 1.5 years, height 137.8 ± 9.4 cm, weight 35.3 ± 12.4 kg) in Japan. They completed an online survey between April 6 and 20, 2021, on their demographic characteristics, lifestyle (recreational screen, sleep, and study times), and baseball activity (frequency of team practice time and voluntary exercise-related baseball) at two-time points: before the pandemic (before March 2020) and during the state of emergency declared in Japan (from April to May 2020). The changes in outcomes between the two-time points were evaluated for significance. Recreational screen time and sleeping time during the state of emergency were significantly increased compared to those before the pandemic (p < 0.001). The frequency of team practice time on weekends during the state of emergency was significantly reduced, and voluntary exercise-related baseball was significantly increased compared to that before the pandemic (p < 0.01). We found that the COVID-19 pandemic changed behaviors concerning activities and exercise among youth baseball players and recommended that such behavioral changes be carefully monitored.
The purpose of this study was to clarify the influence of repetitive pitching by adolescent baseball pitchers on joint range of motion (ROM) and muscle flexibility. [Participants and Methods] Body function of 29 pitchers who belonged to junior high school baseball teams was measured before and after a repetitive 75-throw sequence. Measurement items included joint ROM, muscle flexibility, angle of thoracic kyphosis, latissimus dorsi muscle strength, and posterior shoulder tightness. The speed of the pitched balls was measured as an indicator of performance. [Results] Throw-side shoulder joint internal rotation ROM, non-throw-direction trunk rotation ROM, and non-throw-side gastrocnemius muscle flexibility decreased significantly after the throwing sequence, throwside hip joint inner rotation ROM increased significantly, while pitched-ball speed showed no significant change. [Conclusion] Adolescent baseball players are more likely affected than adults baseball players by rupture of the kinetic chain. Our finding of changes in physical function in the absence of changes in performance suggests rupture of the kinetic chain of normal throwing in these subjects.
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