Heat and Humidity
When exercising in extreme heat and
humidity, the body requires a much greater intake of fluids to maintain health
and wellness. Without the required
intake of fluids, athletes are particularly subject to heat related issues,
including serious illness that can even require immediate medical
treatment.
Heat exhaustion is the most common
type of heat illness and is caused by decreased blood volume due to
dehydration. With heat exhaustion, an individual can experience:
- Dizziness
- Headaches
- Nausea
- Profuse sweating
- Cool or clammy skin
- A rapid or weak pulse
- A body temperature that is at or slightly above
normal.
If you have these symptoms, you should try to cool down as quickly as possible. Body cooling can occur through conduction, convection and evaporation. Evaporation is the most critical defense the body has to overheating. It occurs when the body’s sweat changes on its surface from a liquid to a gas, which then cools the skin. The relative humidity in the air surrounding a person’s body is the most important factor in determining how effective evaporation is for cooling the body’s core temperature.
According to the National Oceanic and Atmospheric Administration’s (NOAA) Heat Index Chart, temperatures and humidity levels in combination below 80 degrees and 40% respectively are of no concern. However, at 88 degrees Fahrenheit and 40% humidity, the heat index is at 88 and caution is needed. If the temperature stays at 88 degrees Fahrenheit and the relative humidity rises to 75%, conditions are dangerous.
This is important to athletes and others who are exposed to heat while required to also exert themselves because the body’s most important mechanism for cooling as mentioned is evaporation. As the heat index rises, and the humidity levels rise, the air cannot absorb as much moisture off the skin and so evaporation slows or even stops, eliminating the body’s ability to cool itself in that way. When conditions are extremely dangerous, or when an athlete overexerts him or herself and fails to hydrate and cool off properly during exercise or activity, heat stroke can occur. The official definition of heat stroke is when the body’s core temperature exceeds 105 degrees Fahrenheit. Heat stroke can result in death if not treated immediately. Other heat related issues that athletes can encounter include sunburn and heat cramps, which are painful spasms in the legs and abdomen.
Nutrition
It is important to remember that nutrition has a significant impact on performance, recovery and body composition. There are basically two types of food: energy dense foods and nutrient dense foods. Energy dense foods are higher in calories relative to the size or volume of the food. These foods should be consumed with caution because it is easy to provide the body with too many calories at times when they may not be needed for energy production. Foods in this category include raisins, cheese, whole milk, butter, French fries, burgers, sweets, energy bars and soft drinks. Nutrient dense foods however are bulkier and take more time and energy to eat. These include grapes, other whole fruit, whole and uncooked raw vegetables, and lean meats, fish or other proteins, such as beans and legumes.
Many athletes discount the role of nutrition in sports performance and staying strong and injury free. So many people say they exercise so they can eat and drink whatever they like whenever they like. Then they are confused when they feel tired, lethargic and don’t get the results they desire in the gym, on the field or on the road. In addition to facilitating increased performance, nutrition also plays a role in staying injury free. Nutritional needs vary by the type, volume, frequency and intensity of training. If you are training more, nutritional needs are greater and it is even more important to pay attention to the type, quality and timing of fuel intake. Overall, athletes should attempt to do the following to maintain a healthy body composition, maximize performance, and reduce the likelihood of injury and the fatigue that can lead to injury via pathokinematics:
- Remove as many processed foods as
possible from the diet
- Concentrate
on getting enough whole fruits and vegetables and lean protein
- Be
careful with starches and sugars, emphasizing them in your diet primarily
during and immediately after intense training.[ii]
Another consideration for athletes is the balance between carbohydrates, protein and fat. Carbohydrates are necessary to replenish glycogen stores that are used up during intense exercise which is discussed further in a later section. Therefore, carbohydrates should be consumed immediately (within the first 30 minutes) after long or intense workouts in order to replenish glycogen stores and refuel for the next workout. Protein must be consumed in order to build muscle and other tissue in the body that is broken down during training. Finally, fats are also required in a healthy balanced diet (despite some commonly held thought) to help maintain the immune system and enable the body to process protein and carbohydrates for use in cells.
Of course, vitamins and minerals are also needed for a well functioning body. Most micronutrients are found in a well balanced, varied diet where foods are consumed in as close to their natural state as possible. If your athlete is not getting a well balanced diet for some reason, sometimes a multivitamin is beneficial, though it should be remembered that vitamins and minerals taken in pill form are never as readily used by the body as those found in a natural diet of healthy, lean, whole and unprocessed foods.
Vitamins and minerals that are especially important for athletes and a few of the ways they impact performance are listed here:
Vitamin A – Improves immune
function; promotes skeletal growth; important for vision
Sources: Beef liver, green, orange and yellow
vegetables
Vitamin
B1 – (Thiamin) helps convert starches and sugar into energy, promotes a
strong heart muscle, prevents fatigue
Sources: whole wheat, dried yeast, oatmeal, peanuts,
port, bran, enriched rice, sunflower seeds, soybean sprouts
Vitamin
B6 – Aids metabolism of protein, carbohydrates and fats, aids in
keeping chemical balance between blood and tissue, builds hemoglobin
Sources: brewer’s yeast, wheat bran, wheat germ, organ
meats, beef, avocados, bananas, milk and eggs
Vitamin
B2 (Riboflavin) – aids in releasing energy to body cells, enables use
of fats, proteins and sugars
Sources: Dairy, liver, kidney, yeast, leafy greens,
fish, eggs
Vitamin
B12 – Promotes use of protein, fats and carbohydrates, helps in
formation of red blood cells, helps nervous system
Sources: Liver, beef, pork, eggs, dairy, shellfish
Vitamin C
– Required to absorb iron, some proteins and folic acid, prevents oxidation of
other vitamins, aids in metabolism of amino acids and calcium, strengthens
blood vessels and maintains bone density, promotes stamina, aids in healing
Sources: citrus fruits, berries, green and leafy
vegetables, tomatoes, cauliflower, potatoes (white and sweet)
Vitamin D
– helps strengthen bones and helps protect the body against osteoporosis and
cancer; maintains nervous system and heart action; modulates neuromuscular
function, reduces inflammation
Sources:
sunlight on human skin,
fish, some fortified foods, light-exposed mushrooms
Vitamin E
– protects the body’s store of vitamin A, tissues and fat from
destructive oxidation; aids blood flow to the heart, regulates protein and
calcium metabolism
Sources: Soybeans, vegetable oils, broccoli, Brussels
sprouts, leafy greens, whole wheat, wheat germ, whole grain cereals, eggs.
Calcium—helps
promote weight loss, build muscle tissue and strengthens bones; helps protect
the body against osteoporosis
Sources: Dairy, soybeans, sunflower seeds, legumes,
sardines
Magnesium
– aids in converting blood sugar into energy, helps regulate body temperature,
promotes absorption and metabolism of other minerals, and activates enzymes for
metabolism of carbohydrates and amino acids
Sources: nuts, figs, seeds, dark green vegetables, wheat
bran, avocados, bananas
Iron
– present in all cells, one of the parts of hemoglobin which carries oxygen to
the tissues by blood circulation
Sources: liver, meat, raw clams, oysters, oatmeal,
nuts, beans, wheat germ
Iodine
– helps burn fat, aids in absorption of carbohydrates from the small intestine,
regulates energy production
Sources: kelp, seafood, vegetables
Copper
– facilitates iron absorption, promotes protein metabolism
Sources: shrimp, beef liver, whole wheat, prunes,
nuts, raw oysters
Zinc
– aids in metabolism of carbohydrates
Sources: eggs, cheese, beef, pork, wheat germ,
brewer’s yeast, pumpkin seeds, popcorn
Niacin
– used with other vitamins to convert carbohydrates into energy
Sources: liver, lean meat, whole wheat, brewer’s
yeast, wheat germ, fish, eggs, roasted peanuts, poultry, sesame seeds, nuts.
Fiber - lowers risk of diabetes and heart disease,
lowers blood cholesterol, maintains healthy digestive system, helps control
blood sugar, aids in weight loss
Sources: fruits such as apples and citrus fruits,
vegetables such as peas, beans, carrots, whole grains, wheat bran, legumes,
nuts, oats, barley[iii]
Dr. Nessler is a practicing physical therapist with over 17 years sports medicine clinical experience and a nationally recognized expert in the area of athletic movement assessment. He is the developer of an athletic biomechanical analysis and author of a college textbook on this subject. He serves as the National Director of Sports Medicine for Physiotherapy Associates, is a Safety Council Member for USA Cheer National Safety Council and associate editor of the International Journal of Athletic Therapy and Training.
[i] NOAA, National
Weather Service Office of Climate,
Water, and Weather Services; “Heat:
A Major Killer,” 1325 East West Highway, Silver Spring, MD 20910 web
site http://www.nws.noaa.gov/om/heat/index.shtml;
[ii] Going Long:
Training for Ironman Distance Triathlons, Joe Friel and Gordon Byrn, The
Ultrafit Training Series, Velo Press, 2003, pages 10, 187.
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