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Heat Illness & Hydration
John Neidecker, DO, ATCSports Medicine Physician
Cooper Bone & Joint Institute
Why do we sweat?
• To cool the body down
• High body temperatures can lead to organ damage
• As muscles contract – heat is produced
How do we sweat?
• Neurological response
• Skin blood vessels vasodialate – stimulating sweat glands
• Sweat evaporates and cools the skin
What does sweat contain?
• Water• Urea• Electrolytes
– Sodium
The composition is highly variable between individuals
• Person• Environment• Body weight• Acclimated/Fitness
level
Performance & Hydration
• Performance has been shown to decrease secondary to dehydration– Physically– Mentally
• Decreases start to happen when there is a decrease in total body water of 2%
Performance & Hydration
• People do not perceive the feeling of being thirsty until there is a decrease in total body water of 3%
When things go wrong…
• Sweat response becomes dysfunctional resulting in – An increase in body
temperature– An electrolyte
imbalance
Electrolyte Imbalance
• Levels too high or too low can cause – Arrhythmias– Seizure– Brain damage
Hyperthermia
• Increase in body temperature can lead to– Heat Stroke– Heat Exhaustion– Heat Cramps
Heat Stroke
• Defined by– Body temp > 104 F– CNS Dysfunction– Organ Damage
Heat Exhaustion
• Inability to continue exercising
• Brain mediated “safety break”
• Temperature not as high as HS
Heat Cramps
• Painful muscle cramps– calves
• Associated with large amounts of sodium loss
Who’s at risk for heat illness?
• Those who have had it before
• Out of shape/Unacclimatized
• Overweight
• Age
Warning signs
• Change in mental status
• Dizziness
• Difficulty walking
• Vomiting
• Hyperventilation
Confused with Concussion
• Take a temperature
What to do if suspected
• Remove athlete from play!!!!!
• Call EMS• Place athlete in a
shaded area• Ice
– Emersion– Bags on head, neck,
armpits, groin
Quick Aside
• Sickle Cell Trait– Not a heat illness– Crisis triggered by
• Dehydration• Hypoxemia
– NCAA D1 – Screening– Does not disqualify from participation
Prevention
• Go into practice fully hydrated
• Wear light colored, loose fitting clothing
• Exercise during the cooler parts of the day
• Acclimate over time– Start 10-14 days before training camp– Start at 10 minutes– Increase by another 10 minutes every 2 days
Hydration Guidelines
• Drink 16 oz of water or sports drink one hour before exercise
• Drink 4-8 oz every 15-20 minutes of exercise
• Exercising less than an hour, drink water
• Exercising more than an hour, drink a sports drink
» 16 oz is about half a liter
After Exercise Hydration
• Weigh yourself before and after practice– For every 2 lbs lost drink 48 oz
• If your urine is dark – you are not drinking enough
History of Gatorade
• Created by researchers at the University of Florida in 1965– “Gator”-aid
• Legend of the 1967 Orange Bowl win over Georgia Tech
Pickle Juice
• Anecdotally, helps with muscle cramps
• High in sodium
Chocolate Milk
• Post-work out drink• Increase protein
synthesis• Increases muscle
glycogen• 16 oz about 40 min
after work out• Low-fat
References
• Armstrong, LE, et. al, American College of Sports Medicine Position Stand: Exertional heat illness during training and competition., Med Sci Sport Exer. 2007. pgs 556-572
• Sawka, MN, et. al, American College of Sports Medicine Position Stand: Exercise and fluid replacement., Med Sci Sport Exer. 2007. pgs 377-390