Maturity-Associated Variations in Resistance Exercise-Induced Hormonal Responses in Young Male Athletes.

PURPOSE: To examine differences in resistance exercise-induced hormonal responses among young athletes according to their maturity levels. MATERIALS AND METHODS: A total of 12 collegiate and 32 junior high school male athletes were enrolled. The junior high school participants were divided into pre-peak height velocity (PHV) and post-PHV groups, according to their PHV ages. The salivary testosterone, cortisol, and human growth hormone levels were analyzed before (pre), immediately after (post), and at 15 minutes after performing body weight resistance exercise. RESULTS: The testosterone levels were higher in the collegiate than in the junior high school group (P < .01) and increased after 15 minutes of exercise (P < .01). A significant decrease in the cortisol levels postexercise in the junior high school groups (P < .01) and an increase in the human growth hormone levels at 15 minutes after exercise in the post-PHV group were observed (P < .01). In the collegiate and post-PHV groups, the testosterone-to-cortisol ratio increased post and at 15 minutes after exercise (P < .01). The testosterone-to-cortisol ratio values were higher in the collegiate than in the post-PHV (at preexercise and at 15 min after [P < .01]) and pre-PHV groups (at all times [P < .01]). CONCLUSION: Exercise-induced acute hormonal responses to resistance exercise may depend on individuals' maturity levels, even in those having the same age.

Longitudinal Age-Related Morphological and Physiological Changes in Adolescent Male Basketball Players.

This study aimed to examine longitudinal age-related changes in muscle morphology and jump and sprint performances of youth athletes. The subjects of this longitudinal study were 41 youth male basketball players who were assigned to late, mid, and early groups based on differences regarding the estimated age at peak height velocity. The vastus medialis, vastus intermedius, rectus femoris, vastus lateralis, biceps brachii, and triceps brachii thicknesses were assessed using ultrasonography. The subjects' anaerobic capacities were evaluated based on Abalakov jumps and 20-m sprint time. After 1 year, the vastus medialis and biceps brachii thicknesses increased significantly in all groups, and the rectus femoris, vastus intermedius, and vastus lateralis thicknesses increased significantly in the late and mid groups, but not in the early group. The Abalakov jumps and 20-m sprint time improved significantly in all groups. The early group's 10-m sprint time improved significantly. Cross-sectional comparisons showed that after 1 year, the early group's Abalakov jumps and 20-m sprint time at baseline, its Abalakov jumps, and 10-m and 20-m sprint times were significantly better than those in the mid and late groups. Hence, significant muscle growth occurred before the athletes reached the age at peak height velocity. During puberty, late maturers' sprint times and jump performances may not catch up with those of early maturers. The speed and tempo of the morphological growth and anaerobic ability of athletes in the same age category depend on athletes' biological maturity.

Epidemiology of lateral ankle sprain focusing on indirect contact mechanism in male and female soccer players: An 18.5-month cohort study.

BACKGROUND: Epidemiological research highlights the need to understand sports injuries for effective prevention. Yet, detailed knowledge about lateral ankle sprain (LAS) in soccer, especially related to indirect contact mechanisms and specific sports movements, remains scarce. This study aimed to determine the prevalence of LAS by examining injury mechanisms, focusing on indirect contact, and analyzing sports-related movements. STUDY DESIGN: Prospective study. METHODS: In this prospective study, 304 high-school and college soccer players (age: 19.0 ± 2.2 years, height: 168.3 ± 10.6 cm, weight: 64.2 ± 11.1 kg) were monitored for 18.5 months. Attendance and LAS incidents were recorded daily. Injury details, including movement at the time of injury, contact presence, and direction, were collected through interviews conducted on the injury day. LAS were categorized into direct contact, indirect contact, and non-contact mechanisms. Direct contact injuries were due to external forces on the lower leg or foot. Indirect contact injuries resulted from impacts on areas other than the lower leg or foot, and non-contact injuries involved no interaction with the ball or opponent. Incidence rates per 1,000 athlete exposures and 95 % confidence intervals (CIs) were calculated, along with rate ratios (RR) to assess sex differences. RESULTS: The study recorded 59 LAS injuries. Indirect injuries were predominant, accounting for 47.5 % (n = 28) of the cases. Men experienced a higher incidence of indirect injuries, with an RR of 2.29 (95 % CI: 1.06-4.96). Outward contact was the most common (77.8 %; n = 21), while inward contact occurred in 22.2 % of the cases (n = 6). CONCLUSION: High school and college soccer players primarily sustained injuries through indirect contact mechanisms, with a significant number of injuries occurring during lateral contact. Men were more prone to indirect contact injuries. Furthermore, 47.5 % of LAS incidents involved reactive movements, and injuries frequently occurred during specific sports actions, such as ball interception.

Study on triphase of polymorphs TiO2 (anatase/rutile/brookite) for boosting photocatalytic activity of metformin degradation.

The elution of pharmaceutical products such as metformin at higher concentrations than the safe level in aquatic systems is a serious threat to human health and the ecosystem. Photocatalytic technology using TiO2 semiconductors potentially fixes this problem. This study aims to synthesize triphasic anatase-rutile-brookite TiO2 using ultrasound assisted sol-gel technique in the presence of acid and its application to photodegradation of metformin under UV light irradiation. Based on X-ray diffraction analysis, a TiO2 sample consisted of anatase (76%), rutile (7%), and brookite (17%) polymorph (A76R7B17) that was fully crystallized. Scanning electron microscopy (EM)-energy dispersive X-ray spectra results showed agglomerated triphasic A76R7B17 with irregular spherical clusters. Transmission EM results revealed that the crystal size of A76R7B17 was 4-14 nm. The Brunauer-Emmett-Teller analysis showed the sample's specific surface area of 149 m2 g-1. The degradation test of metformin demonstrated that the A76R7B17 exhibited a 75.4% degradation efficiency after 120 min under UV light irradiation, significantly higher than using biphasic and single-phase TiO2 photocatalysts. This difference could be attributed to the heterojunction effect of triphasic materials that effectively reduced electron-hole recombination rate as well as the combination of effective electron transfer from conduction band of brookite and anatase and the utilization of wider range of UV-visible light using rutile.

Effect of the COVID-19 Pandemic on Lower Extremity Injuries in Japanese Collegiate Men's Basketball Players.

Background: The coronavirus disease 2019 (COVID-19) pandemic significantly affected the lives of Japanese collegiate men's basketball players. Purpose: To describe the incidence of lower extremity injuries in Japanese collegiate men's basketball during the COVID-19 pandemic and examine the effects of the pandemic on injury patterns. Study Design: Descriptive epidemiological study. Methods: Using data from a surveillance project of the Department of Medicine and Science of the Kanto Collegiate Basketball Federation, the authors included data from 6 men's basketball teams during the 2020-21 and 2021-22 seasons (11 team seasons). Injury rates per 1000 athlete-exposures (AEs) were calculated according to injury type, location, and frequency. Injury burden was estimated by multiplying the injury rate by the mean days lost. Injuries from the 2020-21 to 2021-22 seasons were compared with those before the pandemic (2013-14 to 2019-20 seasons) using injury rate ratios (IRRs), with significant differences indicated when the 95% CI did not include 1.0. Results: In total, 135 lower extremity injuries were reported during 27,249 AEs. The overall injury rate of the 2020-21 to 2021-22 seasons was significantly higher than that of the 2013-14 to 2019-20 seasons (IRR, 1.37; 95% CI, 1.12-1.67). Lateral ankle sprains (IRR, 1.37; 95% CI, 1.02-1.86), hamstring strains (IRR, 2.86; 95% CI, 1.34-6.12), jumper's knee (IRR, 2.68; 95% CI, 1.13-6.37), and stress fractures of the proximal fifth metatarsal (IRR, 7.16; 95% CI, 1.31-39.08) were significantly higher during the 2020-21 to 2021-22 seasons compared with the 2013-14 to 2019-20 seasons. Conclusion: The rate of lower extremity injuries increased significantly in Japanese collegiate men's basketball players during the COVID-19 pandemic. The results of this study emphasize the importance of optimal screening and specific loads for injury prevention when detraining periods are anticipated.

The effects of calf muscle self-massage on ankle joint range of motion and tendon-muscle morphology.

INTRODUCTION: Self-massage using a foam roller (foam rolling) has been used to improve joint range of motion (ROM). However, the effect of foam rolling on the morphology of a targeted muscle, tendon, and muscle-tendon unit (MTU) has not been fully clarified. This study aimed to investigate extensibility changes in the gastrocnemius muscle (GM), MTU, and the Achilles tendon (AT) in terms of maximum ankle dorsiflexion (max-DF) following a foam rolling intervention. This was an interventional study with no controls. METHODS: Study participants comprised 10 male and female students (mean [standard deviation]: 22.7 [2.5] years; height, 164.2 [6.7] cm; weight, 57.9 [7.9] kg). The foam rolling intervention was performed on the right leg plantar flexor muscles for 3 min. The outcomes were max-DF with specified resistance values (ROM-SR) and non-specified resistance values (ROM-NSR) and GM, MTU, and AT extensibility. An ultrasound device was used to determine the rate of change by subtracting the value in a neutral ankle joint position (0°) from the ankle max-DF to identify GM, MTU, and AT extensibility. All outcomes were measured pre- and post-intervention. RESULTS: The range of ankle joint dorsiflexion increased significantly following the foam rolling intervention (Δ: ROM-SR, +4.35 [5.79]; ROM-NSR, +4.18 [4.43]), whereas GM extensibility increased 4.0 mm, although no significant difference was observed pre- and post-intervention. CONCLUSION: Foam rolling was effective in increasing ankle joint dorsiflexion ROM. Moreover, it was suggested that the GM morphology might be affected by the intervention.

Descriptive epidemiology of injuries in Japanese collegiate men's basketball: 2013/2014 to 2019/2020.

BACKGROUND: Basketball is one of the most played sports in the world. However, only a few studies have examined the epidemiology of Japanese collegiate men's basketball injuries. This study investigated the incidence of injury among Japanese collegiate men's basketball from the 2013/2014 to the 2019/2020 seasons and identified unique patterns by comparing our data with the National Collegiate Athletic Association (NCAA) men's basketball data. METHODS: Data from Japanese collegiate basketball teams of the Kanto Collegiate Basketball Federation Division I League during the 2013/2014 to 2019/2020 academic years (23 team-seasons) were used in this study. Injury rates per 1000 athlete exposures (AEs), injury proportions, and the injury rate ratio (IRR) were calculated according to the events, injury types, body parts, and common injury mechanisms. Injury rates were then compared with that from the time-loss injury data of the NCAA's previous reports. RESULTS: In total, 480 injuries during 97,515 AEs were reported, leading to an injury rate of 4.92 per 1000 AEs (95% CI = 4.48-5.36). The overall injury rate was higher in Japan than in the NCAA ([2009/2010-2014/2015] IRR = 1.55, 95% CI = 1.39-1.73; [2014/2015-2018/2019] IRR = 1.64, 95% CI = 1.48-1.82). Lower extremity injuries occurred most frequently (73.5%). Ankle sprain was the most common injury in Japan, with higher injury rates than in the NCAA (IRR = 2.10; 95% CI = 1.72-2.57). The injury rate of concussion was lower in Japan than in the NCAA (IRR = 0.28; 95% CI = 0.14-0.55). CONCLUSIONS: The rates of overall injury and ankle sprain were higher and that of concussion was lower in Japan than in the NCAA. These results suggested the existence of international differences in the pattern or features of injuries in basketball players.

The acute mechanism of the self-massage-induced effects of using a foam roller.

INTRODUCTION: Maintaining flexibility, often defined as range of motion (ROM), is important. Recently, self-massage using a foam roller (FR) has been used in clinical and/or sports settings to effectively and immediately improve ROM. Many studies have found significant increases in ROM following the FR intervention; however, the mechanism of the effect is unclear. We aimed to clarify this mechanism regarding the ROM effects following the FR intervention by evaluating local tissue and autonomic nervous system responses. METHOD: The study employed a crossover design that included a comparison between non-intervention (CON trial: left leg) and intervention (FR trial: right leg) groups. Fourteen volunteers participated. Nine outcomes (passive maximum ankle ROM [ROM with a specified and non-specified passive strength], tissue hardness, skin temperature, water contents, circumference, blood flow velocity, pressure pain threshold, autonomic nervous system, and heart rate) were investigated before (PRE) and 0 min (POST0), 20 min (POST20), 40 min (POST40), and 60 min (POST60) post intervention. RESULTS: Skin temperature, impedance, and circumference changed significantly following the intervention, and increased ROM with non-specified strength was observed. DISCUSSION: Although we found that the FR intervention influenced skin temperature, impedance, circumference, and ROM, adaptability to the intervention may differ depending on an individual's characteristics. Females and/or individuals with a high body water content could obtain greater positive ROM effects than males and/or individuals with a low body water content. CONCLUSION: These findings suggest that the FR intervention may be an effective method to improve ROM, with alterations of skin temperature, impedance, and circumference.

Cross-sectional comparison of age-related changes in the quadriceps femoris in Japanese basketball players.

Background This study examines age-related changes in the quadriceps femoris (QF), subdivided into the vastus medialis oblique (VMO), vastus medialis (VM), rectus femoris (RF), vastus intermedius (VI) and vastus lateralis (VL) in basketball players. Subjects Seventy male basketball players were divided into four groups according to age (12-13, 14-15, 16-17, and 18-20 years). Methods Ultrasonography was used to measure muscle architecture of the VMO, VM, RF, VI and VL. We created cubic approximate expressions and calculated inflexion points to evaluate peak growth age of each muscle head. Results Significant interactions were observed for all QF parts (p < 0.01-0.001). Muscle thickness (MT) in all QF parts was significantly lower in 12-13-year olds than in 18-20-year olds (p < 0.01-0.001). Significant differences were recognised between 12-13 and 16-17-year olds in VM (p < 0.001), RF (p < 0.001) and VL (p = 0.007). MT was significantly lower in 14-15-year olds than in 16-17-year olds in the VM (p = 0.007) and RF (p = 0.026) and in 18-20 year olds in the VM (p < 0.001), RF (p = 0.036) and VI (p < 0.001). Peak growth age was estimated for each QF part (VMO, 155.0 months; VM, 187.8 months; RF, 212.2 months, VI, 188.9 months; VL, 181.1 months). Conclusion QF parts have different growth rates due to differing functions in each muscle head.