Sport-related concussions (SRCs) are common, and the consequences of SRCs are multi-layered. In addition to its immediate effects, a SRC can lead to the development of long-lasting symptoms (i.e. postconcussion syndrome) and the increased risk of other musculoskeletal injuries. Repetitive head impacts may result in, in some cases, potentially irreversible and even fatal changes in the brain such as diffuse cerebral swelling and chronic traumatic encephalopathy. Due to its complexity, the prevention of SRCs must be considered at three different levels - primary, secondary and tertiary. For the primary prevention, the protective equipment such as helmets, headgears, and mouth guards does not reduce the risk of SRCs. While the effects of policy and rule changes to allow less physical contact are inconclusive, the education of proper tackling techniques and its implementation (i.e. practicing without helmets and pads) may be effective in preventing SRCs. Regarding the secondary and tertiary prevention, literature does not support the use of prolonged, strict rest. A brief period (24-48 hours) of physical and cognitive rest followed by a gradual increase of activities will likely facilitate a better recovery. The subthreshold exercise protocol has shown to be safe and reliable, and it seems to minimize the chronic symptoms related to SRCs. Although high-level evidence has yet to be established, early resumption of the monitored, controlled aerobic exercise may become the standard for future SRC recovery.

Over the last 10 years there has been accumulating evidence regarding the epidemiology, aetiology, pathophysiology and management of hamstring strain injuries. However, despite our increasing knowledge base, epidemiological data confirms that hamstring strain injury incidence remain high. Furthermore, high rates of injury recurrence are arguably the most troublesome aspect of hamstring strains because recurring injuries often result in substantially more lost playing time than the original insults. Previous studies have suggested that the activation patterns of each hamstring muscle are not uniform during hip-based and knee-based training as well as during sprinting. The mechanism underlying activation differences among these muscles may involve morphological differences, which may reflect each muscle’s function. In addition, the biceps femoris long head muscle is the most frequently injured area and is susceptible to strain injury during high-speed or high-intensity situations such as sprinting. Thus, to protect the biceps femoris long head from strain injury, an improved understanding of the patterns of hamstring muscle activation during injury inducing movements, such as sprinting, as well as during strength training is necessary. Therefore, the objectives of this article are to provide better comprehension of (i) site-specific activation patterns of the hamstring muscle during sprint performance and during commonly employed strength training exercises, and (ii) the effects of exercise selection on hamstring strain injury risk. This may contribute to sports clinicians and strength and conditioning coaches who specifically design training, injury prevention and rehabilitation programs in respect of hamstring muscle strain based on scientific evidence.

A systematic search of the literature was conducted on PubMed (Medline) and Ichushi Databese. Studies were limited to prospective cohort study or randomized controlled trials (RCTs) of risk factor and/or prevention specific to the elbow injury in baseball players. Seventeen studies met the inclusion criteria as prospective study and one as RCT. In youth, the risk factors for throwing elbow injury in youth baseball players are : increased age ; increased weight and decreased height; pitcher ; increased practice days and pitch counts; poor posture ; decreased the range of motion (ROM) of the shoulder, elbow, and hip. On the other hand, RCTs of preventive intervention were none. In high school baseball players, decreased the ROM of internal rotation in the dominant shoulder were indicated the risk factors of throwing shoulder and elbow injuries. For a RCT of sleeper stretch, a significant reduction in risk of throwing shoulder and elbow injuries was found in the prevention group. In professional players, the prospective studies and RCTs were limited.

Anterior cruciate ligament (ACL) injury is a major concern of the young athletes who are engaged in sport activities. Regardless of the number of research studies focusing on prevention of ACL injury, the incident of ACL injury has steadily increased. Problems associated with ACL injury includes financial burden, short- and long-term decreased physical functionality, high recurrence rate, and early development of osteoarthritis. Thus, prevention of ACL injury is critical. The purpose of this evidence-based report is to provide overview of ACL injury, including mechanism of injury, prospective risk factors, factors associated with prospective risk factors, effectiveness and efficacy of injury prevention exercise, and suggestions for future study to help develop effective ACL prevention strategy.

Exercise in the heat poses unique stress to the thermoregulatory system and body fluid regulation. Understanding the complex interaction between the environmental heat stress and the exercising body is imperative in optimizing exercise performance and safety in the heat. The thermal physiology of human during exercise has been well described in laboratory studies, which provided evidence-based recommendations for practitioners and athletes to follow to maximize their performance. However, confounding variables that are unique to the individual, organizational and environmental context further challenges the scientists to establish strategies in reducing thermal stress during exercise. This review provides a brief overview of human body temperature and fluid regulations and explore ways in which one may optimize performance in the heat through the means of heat acclimatization, proper hydration, and body cooling. Second, safety precautions in the heat to minimize the risk of exertional heat illness are discussed with a recent example of regionally specific activity modification guideline that is being investigated in the United States. Lastly, limitations in laboratory based thermal physiology studies are discussed, such as lack of external validity in simulating the true environmental heat stress and lack of validated method in measuring real-time internal body temperature change and hydration status during exercise.

The purpose of this study was to investigate the characteristic of the ankle joint angle during lateral hop maneuver in individuals with chronic ankle instability. 27 subjects were participated and measured the angle of the ankle inversion/eversion and dorsal/plantar flexion during lateral hop using 3D motion analysis system. The angle of the dorsal flexion at foot contact phase was 0.5±3.9° in normal ankle and 3.7±3.5° in sprained ankle. The sprained ankle had less dorsal flexion position at foot contact phase during lateral hop (p<0.05). The angle of the dorsal flexion at take off phase was 2.3±3.4° in normal ankle and 4.9±3.5° in sprained ankle. The angle of ankle dorsal flexion in sprained ankle was significant greater than normal ankle. There was no significant difference in the angle of the ankle inversion/eversion between the normal ankle and the sprained ankle.

In the present study, we examined the application of cold water immersion (CWI) between Yo-Yo Intermittent Recovery (YYIR) tests as fatiguing task in competitive soccer players. Subjects were 13 male university soccer players, and we conducted YYIR tests on these subjects to simulate the first and second halves of actual games. We compared changes in distance completed in the YYIR tests, skin temperature of the anterior thigh, knee extension strength, vertical jumping height, and 30m splint time under the conditions of 1) CWI between YYIR tests or 2) rest in sitting position. Results showed that the CWI prevented decrease the running distance in the second half YYIR tests. Therefore, CWI had an effect on prevent decrease intermittent high intensity athletic capacity. However, CWI decreased vertical jump height and 30m splint speed such as high power performance. Hence, these results showed a negative effect in high power performance, thereby strongly suggesting the necessity of a re-warmup for actual application in games.

We aimed to identify the injury incidence including non-time-loss (NTL) injuries, which result in less than 24 hours of restriction from participation, in high school baseball players. A total of 80 male players (aged 15-17 years) participated in this study. Athletes were monitored for sports-related injury and number of athlete exposures (AEs) by athletic trainers and assistants. The overall injury incidence during the season was 10.2/1,000 AEs. The incidence of NTL injuries was higher than time loss injuries (7.4 vs. 2.8/1,000 AEs). The shoulder was the most commonly injured body part (2.2/1,000 AEs), followed by elbow (1.7/1,000 AEs) and low back (1.3/1,000 AEs). The shoulder and elbow injuries incidence of regular members (9.1/1,000 AEs) was significantly higher than non-regular members (2.4/1,000 AEs). The shoulder injuries showed significantly higher incidence in pitcher (4.2/1,000 AEs) compared to the other positions (1.7/1,000 AEs). The incidence of lower leg injuries was higher in the winter season (2.1/1,000 AEs) than the other seasons (0.4/1,000 AEs). In the future, preventing their injuries including NTL injuries is necessary.

The purposes of this study were to measure and examine differences in hip range of motion (ROM) caused by position and side, as well as to investigate the association between hip and Glenohumeral joint (GHJ) ROM in collegiate-level baseball players. The participants were 23 collegiate-level baseball players without hip or shoulder joint injuries (11 pitchers and 12 fielders). Hip and GHJ were measured for the following passive ROM variables : 1) hip flexion ROM, 2) straight leg raise, 3) hip internal rotation ROM, 4) hip external rotation ROM, 5) Modified-HBD (M-HBD), 6) Glenohumeral Internal Rotation Deficiency (GIRD), and 7) External Rotational Gain (ERG). This study investigated differences in hip ROM caused by position and side, in addition to respective associations with GIRD and ERG with hip ROM. The data of this study showed that hip ROM differences were not clinically meaningful. The correlations of non-throwing hip flexion and M-HBD of both sides with ERG were significant for pitchers. On the other hand, the correlations between throwing M-HBD and GIRD was significant for fielders.

This study describes the results of heat stroke that occurred in an American football player. The chief complaint of the football player was generalized muscle spasms. Because he remained completely awake and alert, we suspected him to be only suffering from heat cramps. However, the results of a blood test showed that it was a heat stroke. It is difficult to classify the severity of heat illness in the sports field.

Objective : The present study aimed to examine university students’ experience with and expectations from a trainer’s activities and roles, respectively.

Methods : In this cross-sectional study, an online survey was conducted with university students belonging to a tennis, handball, kendo, or athletics club in October 2016. Data were obtained from 76 students. Seven activities of a trainer, such as taping, massage, and warm-up, were targeted. Participants rated the frequency of their experience using the following responses : “never,” “ever (by the expert or not),” or “current (by the expert or not).” Subsequently, those who chose ever (by the expert) or current (by the expert) were categorized as “experienced.” Expectations regarding the roles of a trainer were examined across 7 categories such as conditioning, rehabilitation, and education. Participants rated their importance using the following responses : “very essential,” “quite essential,” “averagely essential,” “not very essential” and “not essential at all.” Subsequently, the first two response categories were defined as “expected roles.”

Results : The proportion of those who experienced an activity of the trainer was the highest for taping (15.8%), followed by massage (14.5%). Warm-up (2.7%) was experienced by the lowest proportion. The proportion of those who expected a role from a trainer was the highest for conditioning (84.9%), followed by rehabilitation (74.7%). The lowest proportion of participants expected a trainer to be involved in education (47.4%).

Conclusion : Few students had experienced a trainer’s activities. However, they expected the trainer to assume roles that may lead to improvement in their performance or that pertain to medical skills.