Summary Exertional heat illness is a broad category of injuries related to heat gains exceeding heat losses Any athlete or laborer who collapses or has a mental status change should undergo prompt medical evaluation Exertional heat stroke is a life-threatening condition that requires immediate whole-body cooling, IV rehydration, and EMS activation Epidemiology The incidence of exertional heat illnesses rises during the warmer months of the year Highest incidence with American football, running, cycling, and adventure races Etiology Exertional heat illnesses arise when body heat gain exceeds heat loss .Predisposing factors include inappropriate heat acclimation, dehydration, sleep deprivation, and prior heat illness Presentation and Treatment Exertional heat exhaustion Inability to continue activity due to heat stress, with widespread peripheral vascular dilation Core temperature of less than 102.2°F(39°C) and an absence of central nervous system dysfunction Presents with profuse body sweat, nausea, and vomiting Treatment: body cooling, rehydration (oral preferred), continued monitoring until symptoms improve Exertional Heat Stroke Hyperthermia (core temp>102.2°F or 40°C), CNS disturbances, multiple organ system failure A medical emergency with a high death rate that results from failure of the thermoregulatory mechanisms of the body Immediate recognition is paramount to survival. Rectal temp >40°C and any CNS change necessitates body cooling Immediate whole-body cooling on-site (cold water immersion), prior to evac (unless other medical complications) IV resuscitation with treatment of secondary medical complications Rapid cooling that lowers body temp within an hour of onset typically results in full recovery Exertional rhabdomyolysis Acute syndrome of muscle destruction producing breakdown product leakage into the bloodstream Presents with muscle pain, weakness, elevated serum creatine kinase, and myoglobinuria Treated with body cooling if necessary, plus aggressive IV rehydration and potential renal dialysis Exertional associated collapse Collapse of a conscious athlete with or without syncope after completion of an exercise Caused by loss of venous return at the end of an exercise Most common condition seen in a marathon medical tent (59-85%) Rule out other serious injuries, then oral hydration and Trendelenburg position Exercise associated muscle cramps Painful skeletal muscle spasm secondary to electrolyte imbalance Affected muscles can be random, individual spams usually lasts 1-3min Treatment is stretching and oral rehydration with combo NaCl Exercise associated hyponatremia Potentially life threatening condition with serum sodium<135 mg/dl and mental status change Usually due to dilutional hyponatremia from prolonged ingestion (>3hrs) of hypotonic fluids Presents with mental status change, peripheral paresthesias, and extremity swelling Severe cases treated with immediate EMS evac and IV hypertonic saline Management Rapid evaluation of any athlete who collapses or has a mental status change during or shortly after an event Immediate whole-body cooling (cold water immersion) should be available at high-risk events Prevention Heat acclimatization, gradual increase in activity with heat exposure Activity modification in high-risk environments Wet bulb temperature temperature read off a thermometer wrapped in a wet cloth 82 - 86 degrees: athletes should have a 1:1 practice to rest ratio > 86 degrees: sports participation should be postponed Return to play No evidence-based recommendations for return to play after exertional heat stroke Recommendation to rest for 7 days, then gradually increase over the next month. Cleared for competition if heat tolerance returns