Michael F. Bergeron

National Athletic Trainers' Association Position Statement: Exertional Heat Illnesses.

OBJECTIVE To present best-practice recommendations for the prevention, recognition, and treatment of exertional heat illnesses (EHIs) and to describe the relevant physiology of thermoregulation. BACKGROUND Certified athletic trainers recognize and treat athletes with EHIs, often in high-risk environments. Although the proper recognition and successful treatment strategies are well documented, EHIs continue to plague athletes, and exertional heat stroke remains one of the leading causes of sudden death during sport. The recommendations presented in this document provide athletic trainers and allied health providers with an integrated scientific and clinically applicable approach to the prevention, recognition, treatment of, and return-to-activity guidelines for EHIs. These recommendations are given so that proper recognition and treatment can be accomplished in order to maximize the safety and performance of athletes. RECOMMENDATIONS Athletic trainers and other allied health care professionals should use these recommendations to establish onsite emergency action plans for their venues and athletes. The primary goal of athlete safety is addressed through the appropriate prevention strategies, proper recognition tactics, and effective treatment plans for EHIs. Athletic trainers and other allied health care professionals must be properly educated and prepared to respond in an expedient manner to alleviate symptoms and minimize the morbidity and mortality associated with these illnesses.

International Olympic Committee consensus statement on youth athletic development

The health, fitness and other advantages of youth sports participation are well recognised. However, there are considerable challenges for all stakeholders involved—especially youth athletes—in trying to maintain inclusive, sustainable and enjoyable participation and success for all levels of individual athletic achievement. In an effort to advance a more unified, evidence-informed approach to youth athlete development, the IOC critically evaluated the current state of science and practice of youth athlete development and presented recommendations for developing healthy, resilient and capable youth athletes, while providing opportunities for all levels of sport participation and success. The IOC further challenges all youth and other sport governing bodies to embrace and implement these recommended guiding principles.

When to Initiate Integrative Neuromuscular Training to Reduce Sports-Related Injuries and Enhance Health in Youth?

Regular participation in organized youth sports does not ensure adequate exposure to skill- and health-related fitness activities, and sport training without preparatory conditioning does not appear to reduce risk of injury in young athletes. Current trends indicate that widespread participation in organized youth sports is occurring at a younger age, especially in girls. Current public health recommendations developed to promote muscle strengthening and bone building activities for youth aged 6 yr and older, along with increased involvement in competitive sport activities at younger ages, has increased interest and concern from parents, clinicians, coaches, and teachers regarding the optimal age to encourage and integrate more specialized physical training into youth development programs. This review synthesizes the latest literature and expert opinion regarding when to initiate neuromuscular conditioning in youth and presents a how-to integrative training conceptual model that could maximize the potential health-related benefits for children by reducing sports-related injury risk and encouraging lifelong, regular physical activity.

Voluntary fluid intake and core temperature responses in adolescent tennis players: sports beverage versus water

Objective: To examine differences in ad libitum fluid intake, comparing a 6% carbohydrate/electrolyte drink (CHO-E) and water, and associated differences in core temperature and other selected physiological and perceptual responses in adolescent athletes during tennis training in the heat. Methods: Fourteen healthy, fit, young tennis players (nine male; five female; mean (SD) age 15.1 (1.4) years; weight 60.6 (8.3) kg; height 172.8 (8.6) cm) completed two 120 minute tennis specific training sessions on separate days (randomised, crossover design) in a warm environment (wet bulb globe temperature: CHO-E, 79.3 (2.6) °F; water, 79.9 (2.2) °F; p>0.05). Results: There were no significant differences (p>0.05) between the trials with respect to fluid intake, urine volume, fluid retention, sweat loss, perceived exertion, thirst, or gastrointestinal discomfort. However, there was a difference (p<0.05) in the percentage body weight change after training (CHO-E, −0.5 (0.7)%; water, −0.9 (0.6)%). Urine specific gravity before training (CHO-E, 1.024 (0.006); water, 1.025 (0.005)) did not correlate significantly (p>0.05) with any of these measurements or with core body temperature. In examining the main effect for trial, the CHO-E trial showed a significantly lower (p<0.001) mean body temperature (irrespective of measurement time) than the water trial. However, the mean body temperature in each trial was not associated (p>0.05) with fluid intake, fluid retention, sweat loss, or percentage body weight change. Conclusion: Ad libitum consumption of a CHO-E drink may be more effective than water in minimising fluid deficits and mean core temperature responses during tennis and other similar training in adolescent athletes.

International Olympic Committee consensus statement on thermoregulatory and altitude challenges for high-level athletes

Challenging environmental conditions, including heat and humidity, cold, and altitude, pose particular risks to the health of Olympic and other high-level athletes. As a further commitment to athlete safety, the International Olympic Committee (IOC) Medical Commission convened a panel of experts to review the scientific evidence base, reach consensus, and underscore practical safety guidelines and new research priorities regarding the unique environmental challenges Olympic and other international-level athletes face. For non-aquatic events, external thermal load is dependent on ambient temperature, humidity, wind speed and solar radiation, while clothing and protective gear can measurably increase thermal strain and prompt premature fatigue. In swimmers, body heat loss is the direct result of convection at a rate that is proportional to the effective water velocity around the swimmer and the temperature difference between the skin and the water. Other cold exposure and conditions, such as during Alpine skiing, biathlon and other sliding sports, facilitate body heat transfer to the environment, potentially leading to hypothermia and/or frostbite; although metabolic heat production during these activities usually increases well above the rate of body heat loss, and protective clothing and limited exposure time in certain events reduces these clinical risks as well. Most athletic events are held at altitudes that pose little to no health risks; and training exposures are typically brief and well-tolerated. While these and other environment-related threats to performance and safety can be lessened or averted by implementing a variety of individual and event preventative measures, more research and evidence-based guidelines and recommendations are needed. In the mean time, the IOC Medical Commission and International Sport Federations have implemented new guidelines and taken additional steps to mitigate risk even further.

Effects of hydration state on plasma testosterone, cortisol and catecholamine concentrations before and during mild exercise at elevated temperature.

This investigation examined the influence of pre-exercise hydration status, and water intake during low intensity exercise (5.6 km · h−1 at 5% gradient) in the heat (33° C), on plasma testosterone (TEST), cortisol (CORT), adrenaline (A), and noradrenaline (NA) concentrations at baseline (BL), pre-exercise (PRE), and immediately (IP), 24 h (24 P), and 48 h postexercise (48 P). Ten active men participated in four experimental treatments. These treatments differed in preexercise hydration status [euhydrated or hypohydrated (HY, −3.8 (SD 0.7)% body mass)] and water intake during exercise (water ad libitum or no water intake during exercise, NW). There were no significant changes in TEST, CORT, or A concentrations with time (BL, PRE, IP, 24 P, and 48 P), or among treatments. However, significant increases from BL and PRE plasma NA concentrations were observed at IP during all four treatment conditions. In addition, HY + NW resulted in significantly higher plasma NA concentrations at IP compared to all other treatments. These results suggest that moderate levels of hypohydration during prolonged, low intensity exercise in the heat do not influence plasma TEST, CORT, or A concentrations. However, plasma NA appears to respond in a sensitive manner to these hydration and exercise stresses.

American college of sports medicine Roundtable on exertional heat stroke - Return to duty/return to play: Conference proceedings

On October 22-23, 2008, an ACSM Roundtable was convened at the Uniformed Services University (Bethesda, MD) to discuss return-to-play or return-to-duty for people who have experienced exertional heat illness (EHI) and to develop consensus-based recommendations. The conference assembled experts from the civilian sports medicine community and the Department of Defense to discuss relevant EHI issues, such as potential long-term consequences, the concept of thermotolerance, and the role of thermal tolerance testing in return-to-play decisions. Although the group was unable to move forward with new consensus recommendations, they clearly documented critical clinical concerns and scientific questions, including the following: 1) no uniform core definitions of EHI; 2) limited validated criteria to assess recovery from exertional heat stroke (EHS); and 3) inadequate ability to predict who may be predisposed to a subsequent heat injury after EHS. Areas of potential future research are identified.

Sports-related Injuries in Youth Athletes: Is Overscheduling a Risk Factor?

Objective:To examine the association between “overscheduling” and sports-related overuse and acute injuries in young athletes and to identify other potential contributing factors to create a working definition for “overscheduling injury.” Design:Survey. Setting:Six university-based sports medicine clinics in North America. Participants:Athletes aged 6 to 18 years (13.8 ± 2.6) and their parents and pediatric sports medicine-trained physicians. Interventions:Questionnaires developed from literature review and expert consensus to investigate overscheduling and sports-related injuries were completed over a 3-month period. Main Outcome Measures:Physicians clinical diagnosis and injury categorization: acute not fatigue related (AI), overuse not fatigue related (OI), acute fatigue related (AFI), or overuse fatigue related (OFI). Results:Overall, 360 questionnaires were completed (84% response rate). Overuse not fatigue-related injuries were encountered most often (44.7%), compared with AI (41.9%) and OFI (9.7%). Number of practices within 48 hours before injury was higher (1.7 ± 1.5) for athletes with OI versus those with AI (1.3 ± 1.4; P = 0.025). Athlete or parent perception of excessive play/training without adequate rest in the days before the injury was related to overuse (P = 0.016) and fatigue-related injuries (P = 0.010). Fatigue-related injuries were related to sleeping ≤6 hours the night before the injury (P = 0.028). Conclusions:When scheduling youth sporting events, potential activity volume and intensity over any 48-hour period, recovery time between all training and competition bouts, and potential between-day sleep time (≥ 7 hours) should be considered to optimize safety. An overscheduling injury can be defined as an injury related to excessive planned physical activity without adequate time for rest and recovery, including between training sessions/competitions and consecutive days.

Erythrocyte sickling during exercise and thermal stress.

Objective:To examine effects of exercise in the heat and fluid intake on erythrocyte sickling and neutrophil activation in carriers of sickle cell trait (HbAS). Design, Setting, and Participants:Six African American men (2 HbAS; 42% HbS, 4 HbAA; 20.7 ± 0.8 years; 87.4 ± 9.6 kg) participated in 2 randomized sessions (separate days) each consisting of 45 minutes of brisk walking (treadmill) in a hot (33°C) environment. Intervention:Subjects consumed no fluids or fluid for 3 hours prior to (ad libitum) and during (1.02 L) testing. Main Outcome Measurements:Core temperature, heart rate, and perceived exertion were measured. Forearm venous blood was analyzed for percent erythrocyte sickling and plasma myeloperoxidase. Results:Time-averaged heart rate (126.6 ± 5.7 vs. 146.7 ± 5.9 bpm; P = 0.02) and core temperature (37.6 ± 0.1 vs. 38.1 ± 0.1°C; P < 0.05) responses were lower during fluid versus no fluid, with no statistically significant difference in perceived exertion (12.3 ± 0.5 vs. 13.6 ± 0.4; P = 0.06). Erythrocyte sickling progressively increased (to 3.5%–5.5%) for HbAS carriers during no fluid exercise only. No sickling was detected in HbAA subjects. Plasma myeloperoxidase responses to exercise were greater (P = 0.03) in HbAS versus HbAA. Conclusions:Fluid ingestion at a rate sufficient to offset a body weight deficit can effectively reduce erythrocyte sickling during exercise in the heat.

Consortium for Health and Military Performance and American College of Sports Medicine Consensus Paper on Extreme Conditioning Programs in Military Personnel

A potential emerging problem associated with increasingly popularized extreme conditioning programs (ECPs) has been identified by the military and civilian communities. That is, there is an apparent disproportionate musculoskeletal injury risk from these demanding programs, particularly for novice participants, resulting in lost duty time, medical treatment, and extensive rehabilitation. This is a significant and costly concern for the military with regard to effectively maintaining operational readiness of the Force. While there are certain recognized positive aspects of ECPs that address a perceived and/or actual unfulfilled conditioning need for many individuals and military units, these programs have limitations and should be considered carefully. Moreover, certain distinctive characteristics of ECPs appear to violate recognized accepted standards for safely and appropriately developing muscular fitness and are not uniformly aligned with established and accepted training doctrine. Accordingly, practical solutions to improve ECP prescription and implementation and reduce injury risk are of paramount importance.