Exertional Heat Stroke Basics: What Strength and Conditioning Coaches Need to Know
Recently, an article in the Journal of Strength and Conditioning Research
(20(3):462, 2006) regarding the recognition and acute treatment of exertional heat stroke (EHS) presented a survival strategy for this condition (4
). Despite many efforts by health professionals to educate others about EHS, fatalities related to this condition have persisted in the U.S. over the past couple of years. EHS is defined as an elevated core body temperature (>40-41°C [104-105.6°F]) associated with central nervous system dysfunction (1,2
). With rapid recognition and effective treatment, an athlete experiencing EHS can be rapidly cooled and avoid fatal consequences (1,4,5
). Furthermore, knowledge of the risk factors associated with EHS can assist coaches, strength and conditioning coaches, athletic trainers, and athletes in the prevention of EHS. Several researchers have distinguished some of the risk factors present in previous cases of EHS (5,8,9
The predisposing factors linked to EHS can be grouped as intrinsic and extrinsic, having to do with physiologic, environmental, or organizational aspects (8
). Physiological risk factors linked to EHS include an existing illness, an overzealous athlete, sleep deprivation, poor physical fitness, non-acclimatization (9
), and dehydration (1,2,5,8
). A major EHS risk factor is an unmatched physical intensity of exercise for the athletes' current level of fitness. Many instances of this condition may be avoided if the level of activity is maintained at a level that the athlete can handle, or is progressed at a moderate pace. Environmental factors are also believed to play a large part in increasing the risk of exertional heat illnesses. According to the 2007 ACSM's Position Stand on Exertional Heat Illnesses, a wet-bulb globe temperature (WBGT) ≥30°C (86°F) is an indication that athletic practices or events should be rescheduled or delayed (1
). Similar environmental conditions should prompt strength coaches to modify activity at a minimum. In a case study of 6 heat stroke fatalities, in 5 out of 6 cases, the WBGT was ≥ 27°C (8
Organizational risk factors can easily be modified in order to decrease the possibility of EHS. These factors include assuring sufficient work-to-rest ratios, avoiding exercise at the hottest times of the day, maintaining proper hydration, and varying exercise duration based on environmental conditions (5,8
). Coaches and athletic trainers can decrease these risks by ensuring that athletes are properly heat acclimatized and are not exercising with an existing illness or in a dehydrated state. Furthermore, athletes should be given sufficient rest breaks with adequate time for hydration and recovery, both during and between workout sessions or practices.
An accumulation of risk factors (intrinsic and extrinsic) may further exacerbate an athlete's EHS risk. In the case report of 6 heat stroke fatalities, 100% of the fatal cases had improper exercise intensity for physical fitness level and an absence of proper medical triage (8
). However, in 128 other cases the most prevalent risk factors were poor physical fitness, sleep deprivation, and a WBGT of 27°C or greater (8
). Furthermore, the most common organizational risk factors were exercising during the hottest times of day, poor physical fitness, and lack of proper medical treatment (8
Education on the possible risk factors of EHS is essential in the prevention and/or proper treatment of this condition. An athlete's knowledge of the risk factors associated with EHS may decrease the risk by ensuring the athlete has had adequate sleep, is in good physical fitness, and is properly hydrated prior to exercise. Some simple modifications to a coach's plan can also reduce many of the risks of EHS.
Since the strength coach often oversees off-season activity and has knowledge of normal actions and personalities of the athletes they are supervising, it is important for them to know the basic signs and symptoms of EHS. A strength coach may not be medically trained, and thus, should not be responsible for the recognition of EHS. However, they should know that a characteristic sign of EHS is an athlete acting out-of-sorts or abnormally for them. If the strength coach is on site, and notices an athlete acting in such a manner, they should immediately refer this athlete to the athletic trainers for evaluation to avoid potentially serious complications (4
). In this case, the athletic trainers can then assess rectal temperature and initiate cooling without delay to prevent fatality (4
EMERGENCY ACTION PLAN
A written emergency action plan (EAP) specific to heat illnesses should be drafted and reviewed by the team physician and athletic training staff. Included in the EAP is the who, what, and how regarding emergency medicine that will be provided for a suspected EHS patient. For example, specific steps should be in place for the situation that may arise when an athlete collapses when participating in off-season conditioning sessions with a strength coach. Time to treatment is a major predictor of patient outcome (4
). The documented course of action should include how medical personnel will be contacted and an estimate of how long it may take for them to respond to the situation.
Only trained medical personnel should assess and treat an athlete in these situations (i.e., team physician or athletic trainer). These individuals are the only medical personnel specifically trained to appropriately assess and treat acute EHS. However, the strength coach is part of the team and may assist in the acute treatment of safely immersing the victim in cold water (4
). We also encourage the sports medicine team and strength coaches to practice the EAP during the off-season in the same manner that spine boarding is typically practiced.
Another essential aspect of the EAP is that local emergency medical personnel (EMTs, paramedics, etc.) should be familiar with the steps within the EAP. This will assure an understanding of what will take place in the event of an EHS. The more individuals involved in the planning will also help to avoid any conflict when the transition of care takes place. If everyone is on the same page prior to an episode, conflict can be worked out in advance to avoid confrontation or a difference of education regarding exertional heat illness management.
Since the main determinant of outcome following EHS is the amount of time core body temperature remains above a critical threshold, the primary goal of treatment is immediate cooling (6
) Emergency medical personnel can be summoned, but it is most important to cool the victim first, and have them transported second (3,4
). The most vital treatment that can be provided is whole-body cooling using cold-water immersion (1-4
). Therefore, a sturdy 100-gallon Rubbermaid® stock tank (http://www.rcpworksmarter.com
) filled with cold water should be available at all workout sessions in the heat in the event that an athlete requires immersion. The immediate situation normally requires no short-term advanced care. Following cooling, the athlete should then be transported via ambulance to a hospital for follow-up care.
RETURN TO PLAY
The athletic trainers and team physician at your school should determine a plan for the safe return-to-play following EHS based on the most recent guidelines from the ACSM (1
). These outline the premise that there may be a temporary heat intolerance following EHS and a gradual increase in activity after physician clearance aids in the prevention of a subsequent episode (7
). This gradual increase (assuming they respond well to each progressive level) in activity includes ramping up the amount and intensity of exercise as well as the equipment or clothing used during activity. For example, the first day back to activity may include only about 30 minutes of activity at about 50-60% intensity with no equipment. This may progress to 90 minutes of activity at 70-80% intensity with upper extremity protective equipment by day 5. Normal return to activity to 100% with full equipment will take about 7-10 days following physician clearance to facilitate a full and safe recovery.
Complete prevention of EHS in athletics is nearly impossible. Strength coaches need to be aware of the risks of this potentially deadly heat illness. Proper assessment and treatment of EHS virtually guarantees survival. It is essential that athletes and coaches understand this fact and work with their sports medicine staff to optimize prevention, recognition, and treatment of EHS.
1. Armstrong, LE, Casa, DJ, Millard-Stafford, M, Moran, DS, Pyne, SW, and Roberts, WO. Exertional heat illness during training and competition. ACSM Position Stand. Med Sci Sports Exerc 39: 556-572, 2007.
2. Binkley, HM, Becket, J, Casa, DJ, Kleiner, DM, and Plummer, PE. National Athletic Trainers' Association position statement: Exertional heat illnesses. J Athl Train 37: 329-343, 2002.
3. Casa, DJ, Almquist, J, Anderson, S, et al. Inter-Association Task Force on Exertional Heat Illnesses Consensus Statement. NATA News. June, 2003. pp.24-29.
4. Casa, DJ, Anderson, JM, Armstrong, LE, and Maresh, CM. Survival strategy: Acute treatment of exertional heat stroke. J Strength Cond Res 20: 462, 2006.
5. Casa, DJ, Ganio, MS, Armstrong, LE, and Yeargin, SW. Exertional heat stroke in competitive athletes. Curr Sports Med Rep 4: 309-317, 2005.
6. Casa, DJ, McDermott, BP, Lee, EC, Yeargin, SW, Armstrong, LE, and Maresh, CM. Cold water immersion: the gold standard for exertional heat stroke treatment. Exerc Sports Sci Rev 35: 141-149, 2007.
7. McDermott, BP, Casa, DJ, Yeargin, SW, Ganio, MS, Armstrong, LE, and Maresh, C. Recovery and return to activity following exertional heat stroke considerations for the sports medicine staff. J Sport Rehab 16: 163-181, 2007.
8. Rav-Acha, M, Hadad, E, Epstein, Y, Heled, Y, and Moran, DS. Fatal exertional heat stroke: A case series. Am J Med Sci 328: 84-87, 2004.
9. Wallace, RF, Kriebel, D, Punnett, L, Wegman, DH, Wenger, CB, Gardner, JW, and Kark, JA. Risk factors for recruit exertional heat illness by gender and training period. Aviat Space Environ Med 77: 415-421, 2006.
[COLUMNS: The Journal of Strength and Conditioning Research Corner]
McDermott, Brendon P MS, ATC; Lopez, Rebecca M MS, ATC; Casa, Douglas J PhD, ATC, CSCS; Kraemer, William J PhD, CSCS, FNSCA
Human Performance Laboratory, Department of Kinesiology, Neag School of Education, University of Connecticut, Storrs, Connecticut
* Brandon P. McDermott, is Research Assistant and Doctoral Candidate in the Department of Kinesiology at the University of Connecticut, Storrs, Connecticut.
* Rebecca M. Lopez, is Research Assistant and Doctoral Candidate in the Department of Kinesiology at the University of Connecticut, Storrs, Connecticut.
* Douglas J. Casa, is Associate Professor of Kinesiology and Director of Athletic Training Education at the University of Connecticut, Storrs, Connecticut.