Hot, Hazy, Humid? Hydrate!

by Dr. Ann L. Engelland

(July 3, 2008) When you just think it can’t get any more humid, the dark clouds roll over, thickening the air until it feels like we are breathing through scuba gear. Football camp has begun on the Mamaroneck High School field across the street from my office and I marvel/cringe at the droves of kids in complete regalia, wondering about body temperatures inside their gear. For teams practicing on the new turf fields, the risk is significantly higher to athletes, and coaches and parents need to be aware of the increased risk of heat stress.

This hazy, hot, humid weather is not likely to let up any time soon, and we need to stay mindful throughout the summer of the effects of heat. Some knowledge and a bit of preparation will prevent a lot of problems.

Why is this so important? Heat injury can be life threatening and young people are more vulnerable than adults. If that isn’t convincing enough for your high school athlete, a reminder that athletic performance diminishes when a body is a mere 1-2% dehydrated might help. Considering that a person doesn’t normally even perceive thirst until 3-5% dehydration, it is clear that performance and well-being can drop quickly if hydration is not attended to.

Following are some guidelines for fluid management:

Pre-training (or exercise):
Correct the deficits from the previous day’s workout
2-3 hours before: 12-16 ounces
Shortly before: 8-12 ounces

During Training:
This is the most important time, of course. The recommendations are:
8-12 ounces every 15-20 minutes in high school athlete
4-6 ounces every 15-20 minutes in younger athlete

For most athletes, if the workout is less than 60-90 minutes, water is the preferred beverage.

Exceptions to this rule include the following situations:

  • Athletes who have whitish salt crusting when they sweat, indicating a heavier than usual sweat salt content, should drink sports drinks (for example, Gatorade)

  • Athletes who say they will vomit if they put water in their stomachs can hydrate with salt/sugar drinks to speed up gastric emptying (into the intestine that is!).

  • Athletes (especially young ones) who will not adequately hydrate if the solution is not colored, sugary, salty or flavored may need sports drinks.

After Training:
Any beverage (non-alcoholic) is fine. Alcohol is a diuretic and will dehydrate the body further, putting it at a disadvantage for play the next day.
For every pound of weight lost, an extra 16 ounces of fluid should be consumed.

What about heat stress?

Heat stress can be divided into four increasingly severe categories:

Heat cramps: very painful muscle contractions that can look like an injury. Treatment consists of passive stretching, ice and fluids (IV if not tolerated by mouth). Although pro athletes try pre-game icing, it is not proven to work.

Heat syncope (or fainting): this is also called “finish line collapse” and happens after an athlete crosses the line and typically stops without cooling down gradually. Nausea and fatigue with or without fainting are the hallmarks. The key to prevention is to “keep ‘em moving at the finish line” to encourage circulation until the body re-equilibrates.

Heat exhaustion: an inability to continue to exercise in the heat. Symptoms include intense fatigue, nausea, or fainting while exercising. It is probably caused by a combination of sodium and water depletion. Athletes competing in events longer than 4 hours are at particular risk. These include all day tournaments, marathons, more than one game and/or training session in a day, etc. Treatment includes cooling, hydration and ER evaluation if necessary. Athletes who have experienced heat exhaustion may not be ready to return to play for 48 hours or more after an episode.

Heat stroke: characterized by an elevation of core body temperature rising over 40 degrees centigrade. It is characterized by muscle and nervous system impairment and brain symptoms such as confusion, agitation, combativeness and seizures may be the presenting signs. Heat stroke is a true emergency and requires EMS management; mortality up to 25% has been reported. It may take months for an athlete to be well enough to return to play due to muscle and brain injury. Readiness should be documented by lab tests and clinical testing by a knowledgeable trainer or clinician.

In the Marines basic training camps, if soldiers collapse in the heat, they are treated to the “silver bullet,” a rectal thermometer to check core temperature and then a large bright orange “X” spray-painted on their backs for the duration of training as a warning that they are at risk.

How do we prevent heat stress and injury?

A few basic rules will help prevent problems:

Acclimatization: Athletes who are planning on sports pre-seasons in the heat of August need to acclimatize. That means that for 4-7 days beforehand they should be out of the air conditioning and exercising in the heat. This expands the blood volume and charges up the sweat glands to make them more efficient at fluid and temperature control.

Avoid/beware of “thermogenic” substances: These are substances that increase the body’s heat and include caffeine, typical ADHD medications, antihistamines and Power drinks (like Red Bull).

Maintain fluid intake: This should be a part of training before, during and after working out. Again, alcohol has no business in a body during training. Rehydration between workouts is often forgotten.

Avoid “high risk” conditions: Standards and recommendations exist for determining the safety of various combinations of heat and humidity for athletes. Briefly, and a good rule of thumb to remember is that humidity over 50% combined with temperature over 90 degrees means that practice and training should be without gear and in shorts with water breaks and rest periods every 15 to 20 minutes. Tables for humans (and cattle, elk, poultry!) can be found at a site of national weather service.

About those artificial turf fields?

The surface temperature and therefore the transfer of heat to the athlete (and coaches or bystanders) is much higher than on natural turf or even on asphalt. Surface temperatures can be in excess of 150 degrees on a 90 degree day. Obviously this can contribute to excessive fluid losses, burns, heat illness, and exhaustion. Watering down these fields can bring down the heat somewhat, but often not for the length of a game. Coaches and school personnel will need to be better informed and weigh the risks to their players under hot and humid conditions.

In summary, parents, coaches and athletes need to remember that:

  • Young kids are especially vulnerable to fluid loss.

  • Re-hydration between workouts is critical.

  • Athletes should keep moving and cool down slowly.

  • Any neurologic involvement suggests heat stroke and is a true emergency.

  • Acclimatization is a key to prevention.

References: Many thanks to Michele LaBotz, MD who presented much of this information at the Sports Medicine Course of the American Academy of Pediatrics in Vancouver in June 2008. See also, Parents' and coaches' guide to dehydration and other heat illnesses in children on the National Athletic Trainer’s Association website.

Dr. Engelland has a practice in Mamaroneck devoted to Adolescent Primary Care. She now accepts Aetna and Hudson Health Plan. Dr. Engelland can be reached at 698-5544 or AnnEngellandMD.com