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Staying Safe In The Summer Heat

August 30, 2010

by: Kimery Duda and The Expedition School Staff and Expedition Medical Team

Staying safe in the Summer heat is always a concern for endurance athletes like cyclists.  Even in the shade of the trees on a mountain bike trail, the heat we experience in Central Texas can play havoc on you if you aren’t properly prepared or paying attention to warning signs that your body is giving you. Proper nutrition and hydration is a key component to making sure you have a good cycling experience in the Summer sun.

Our friends over at the The Expedition School, and the folks who staff their Expedition Medical Team and work many of the cycling events in and around Austin, have put together this great piece to help us all learn about the dangers of prolonged heat exposure and some of the things to do to take care.

Heat Related Illness and Hyponatremia.
The Expedition Medical Team witnesses far too many athletes succumbing to heat related illness and hyponatremia. Our goal is for this article to reach the incredible community of adventure athletes, cyclists, swimmers, trail runners, paddlers, and the bystanders who support them and, teach you the basics of prevention, recognition, response and treatment.
Air temperature, humidity, and dehydration are common risk factors associated with heat illness. Heat related illness occurs in hot humid temperatures where body cooling by evaporation is limited either by humidity levels and/or excessive clothing layers. Heat illness falls into three categories: heat cramps, heat exhaustion, and heat stroke.

Heat cramps occur from excessive sweating (diaphoresis) during strenuous activity. Sweating depletes the body’s salt and moisture, which leads to dehydration. The low salt level in the muscles causes forceful and painful muscle contractions, usually in the quads, hamstrings, abdomen, or arms. If athletes do not take in enough–nor the right balanced–fluids as they sweat their blood actually thickens. If an athlete recognizes any signs or symptoms of heat related illness, he or she should treat the problem immediately.

Heat exhaustion occurs when the body gets too hot and fluids are not replenished at a balanced rate. Thus, the body becomes dehydrated. The hypothalamus –which is the part of the brain that controls hunger, thirst and temperature–receives input from temperature receptors throughout the body. When blood temperatures rise, the neurons fire more rapidly and the body systems that regulate temperature become overwhelmed. The body develops more heat than it can release and it develops signs and symptoms of shock, nausea, vomiting, headache, chills, and urine that is dark.

Heat stroke is the most severe form of heat related illness and is a true medical emergency. Heat stroke occurs when the internal body core temperature exceeds 104 degrees F (40 degrees C). When the athlete competes, the body core temperature rises and, if the athlete continues to compete –ignoring the signs and symptoms of heat cramps and/or heat exhaustion–their condition may have fatal results. Athletes may
develop an altered level of consciousness, seizures, loss of consciousness, and successive vomiting.

It’s not the heat so much as it’s the humidity…”

Relative humidity (RH) indicates how moist the air is. When both relative humidity and air temperature is high and the air is almost saturated with water vapor (humidity), the body moisture does not evaporate as efficiently. As a result the less evaporation occurring, the less cooling.

Dangerous results can occur if athletes ignore what their bodies are trying to tell them. Athletes should consider the environmental conditions, their individual needs, the intensity of performance, duration of ride, fitness levels, nutrition prior to, during, and post event, and frequent fluid and electrolyte balance–again prior to, during, and post event.

Consider two internal factors:
How hard we are working our bodies and for how long.

Now, consider two external factors:
Heat Index vs. Relative Humidity.

Heat Index (HI) is sometimes referred to as the “apparent” temperature. The HI, given in degrees F, is a measure of how hot it feels when relative humidity (RH) is added to the actual air temperature.

Relative Humidity indicates how moist the air is. RH may be defined as the ratio of the water vapor density (mass per unit volume) to the saturation water vapor density, usually expressed in percent.

Evaporation is a cooling process and, fortunately for cyclists, this is a constant (as long as you keep pedaling). As temperatures rise, the main source for the body to cool itself is by perspiration. As perspiration condensates on the skin, the wind hits the skin and immediately prompts evaporation. Evaporative cooling is the most effective way for us to cool the body temperature. To expedite this, you can, cool yourself in a transition area of a tri by utilizing a misting/hydration/wind system, which some events have. If the event is not providing one, you can make one out of a spray water bottle (keep in an ice cooler for greater effect) and spray the cool water directly on your skin. If there is a body of water nearby, immerse yourself and then immediately head to a canopy or direct shade and get fanned, or spray yourself with a water bottle as you ride.

If you are feeling nauseated and/or vomit, make certain to seek medical attention immediately. If you are far from medical response, find shade, lay down and elevate your feet no more that 12” off the ground and gradually rehydrate with salty foods and/or a sports drink and, call and wait for medical personnel to arrive. Lastly, we ask that you take care of each other and utilize the buddy system. Expedition Medical Team cannot be everywhere all of the time. We rely heavily on our community of good Samaritan athletes to help recognize and respond to these situations immediately–and, call 911 ASAP if a medical emergency arises.

Signs and Symptoms of Heat Related Illnesses:

Heat Cramps
• Heavy sweating / diaphoresis
• Abdominal and/or muscle cramps
• Fatigue

Heat Exhaustion
• Nausea/Vomiting
• Feeling weak/confused
• Fast heartbeat
• Headache
• Dark colored urine, which indicates dehydration
• Fatigue
• Chills
• Cool, pale/flushed, moist or red skin

Heat StrokeThis is a medical emergency and the patient needs to be transported to a medical facility immediately!
• Change in level of consciousness
• Loss of consciousness
• Frequent vomiting
• Combative, feeling anxious
• Shortness of breath or difficulty breathing
• Seizures
• The inability to spit
• Dry mucous membranes (lack of sweating)
• High fever (greater than 104 degrees F / 40 degrees C)

Prevention, Prevention, Prevention: Heat Related Illness and Hyponatremia
• Acclimate. Acclimatization means gradual exposure to the heat and humidity. Think on how you acclimate to altitude–same theory applies here. You can achieve this by exercising in the heat for short periods, gradually increasing the time in the heat over a period of 10 to 14 days.
• Avoid alcohol, caffeine, and carbonated beverages.
• Avoid certain medication or drugs that can increase risk for heat illness. Examples include but are not limited to: antihistamines, decongestants, certain asthma medications, Ritalin, water pills (diuretics), illegal drugs, diet pills, laxatives, some meds that treat mental health issues (antidepressants and antipsycholitics), seizure medications (anticonvulsants), and alcohol
• Avoid certain nutritional supplements. Some may contain stimulants such as ephedrine, ma huang or caffeine. These substances can dehydrate the body and/or increase metabolism and heat production. They are of particular concern to people with underlying medical conditions such as hypertension, asthma and thyroid dysfunction.
• Condition your body. Be honest! Are you fit enough to sustain a peak performance level for an extended length of time?
• Drink and eat right. To prevent dehydration or heat exhaustion, athletes need to drink “optimally but not maximally” before, during, and after play. Eat nutritious foods as long as you can tolerate them during play which contain plenty of sodium (salt), potassium, and zinc.

There are dangers in OVERHYDRATING!

Too much water can result in a condition known as hyponatremia. Too much water without proper balanced nutrition of sugar, salt, potassium and zinc can dilute the vital nutrients needed to sustain performance.  Consult with a physician about maintaining a good fluid and electrolyte balance.

Hyponatremia occurs when your blood level of sodium is low. Sodium is an electrolyte and, can be depleted by drinking too much water. Athletes need to be aware of the balance replenishment combination of sodium, sugar, potassium and zinc while competing in endurance sports. Signs and symptoms are very similar to that of heat exhaustion.

One tool that Expedition Med Team utilizes is asking the athlete for a dietary recall within the last 6 hours of the start of the event. If the athlete clearly did not intake salt, we suspect hyponatremia. We do not give water but, instead administer salty foods and sports drinks and/or sodas depending on how much nausea/vomiting is on board with the patient. Signs and symptoms for hyponatremia are similar to those aforementioned in heat cramps, heat exhaustion, and heat stroke. Again, dietary recall is key in administering the best aid for the athlete.

Nutrition is an important aspect of keeping the body going during and after competition. Remember, the body needs more than just an energy bar and some fruit. Here are some ideas on certain snack foods to eat while competing and/or transitioning. Remember to eat real food (a sandwich) as long as you can tolerate it. Save the energy bars for last resort snacks instead of first resort snacks.

Nutrition Ideas During Competition
Potassium is important. Good sources of potassium include:
• Sports drinks (i.e. Gatorade, Powerade)
• Yogurt
• Grapefruit juice
• Bananas
• Nectarines
• Oranges

Sodium is important. Good sources of sodium include:
• Sports drinks
• Vegetable juices
• Pretzels
• Salted Nuts
• Cheese crackers
• Salted chips
• Peanut butter
• PICKLES and/or pickle juice

Fluids are important.
• Water
• Sports drinks

Post competition, carbohydrates are important.

Foods rich in carbohydrates include:
• Potatoes
• Honey
• Cereal
• White bread
• Corn chips
• Sports drinks
• Jelly beans
• Rice cakes
• Bagels
• Crackers
• Gummy candies

As a reminder, here are a few things to also consider and remember when getting ready to face the heat:

• Monitor your urine. If it’s clear and copious, then you’re hydrated. If it’s dark yellow like apple juice, you’re dehydrated and need water and electrolyte replenishment.
• Previous illness from a cold, fever, gastrointestinal illness, or sickle cell trait can negatively impact hydration.
• Rest and cool down after play. Allow your body to recuperate from the beating of a Summer century ride! Find shade and cool off. Evaporative cooling is the most efficient and practical means of cooling patients. Skin should be wet with room temperature water and placed in front of cooling fans.
• Weigh yourself before you compete. The most accurate method for determining your level of dehydration is by recording your weight change before and after an event. Weight loss equals water loss. If you lose more than 5 percent of your weight, seek medical care immediately.
• Wear light colored clothing. Dark clothing absorbs heat.
• Wear sunscreen. Sunscreen of SPF of 15 or more is good.
• Get in to the shade! Head in to the shade when not competing and, choose the shaded routs when competing (like longs stretches of pavement shaded by trees on one side). Shaded tents or umbrellas at rest stops help.

Thanks to the folks over at The Expedition School for reminding us to take care as we gear up for the final Summer cycling events in and around Austin. Stop in any Bicycle Sport Shop location to pick up your favorite sports nutrition snacks and drink mixes today and be ready for tomorrow’s ride!

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