Prevention of Heat Strokes

Heat stroke is a general term of the disorder caused by the imbalance of the water and salt (sodium) content in a body or breakdown of adjustment function in a body under the environment of high-temperature and humidity. The symptoms of heat strokes are as follows.

Symptoms of Heat Strokes

  • Vertigo/faintness
  • Muscle soreness/charley horse
  • Drenching sweat
  • Headache/unpleasant feelings/nausea/vomiting/malaise/despondency
  • Consciousness disorder/convulsion/impaired limb movement
  • Hyperthermia

Classification of Heat Strokes and Response

First Degree Vertigo/faintness・・・mean dizziness. It’s also called syncope.
Muscle soreness/charley horse・・・mean muscle cramp. They are also called heat paralysis.
Drenching sweat
Usually respond on the spot
Taking a rest at a cool place, cooling body surface, taking water and sodium by mouth.
Second Degree Headache/unpleasant feelings/ nausea/vomiting/ malaise/despondency・・・
mean feeling tired and weak, etc. Conventionally, it was called “heat exhaustion”.
Go to a medical institution
Management of temperature, taking a rest, and taking enough water and sodium (If it’s difficult to take them by mouth, take them via an intravenous drip.)
Third Degree Consciousness disorder / convulsion / impaired limb movement・・・Response to a call or stimulation is unusual. Having convulsion or being unable to walk straight, etc.
Hyperthermia・・・If you touch the body, you will feel the heat.
Conventionally, it was called “heat hyperpyrexia”.
Need to be hospitalized for treatment
Management of temperature (In addition to cooling body surface, lowering the temperature and cooling blood vessels are needed. Management of breathing and circulation are also needed.)

Only when the symptoms of the first degree are gradually improved, the first-aid treatment and watching will work out.
If the symptoms of the second degree are seen and the improvement of the first degree can’t be seen, the patient should be carried to a hospital immediately (people around the patient should judge that).
Whether the symptoms are classified into the third degree or not is judged by rescue workers or medical examination and check at a hospital.
(Excerpt from the Classification of Heat Strokes 2015 by Japanese Association for Acute Medicine)

Prevention of Heat Strokes

  1. Hydration: It is important to frequently take water with salinity (such as sport drink) in hot seasons. As the composition of water you take, water with salinity of 0.1-0.2% is suitable. When you choose a commercially available drink, you should check the ingredients, and pick out the one that includes sodium of 40~80㎎ per 100ml. For example, Pocari Sweat, Amino-Value and energen have sodium of 49㎎ per 100 ml.
  2. Take a break to have water: Take a break to have water and reduce the increase in temperature.
  3. Take care of sportswear: It is important to choose a suitable sportswear when exercising. The pneumatic, air permeability, heal retaining property, hygroscopic property, desorption moisture, etc. are different, depending on the materials in exercise. Prepare several types of sportswear you like and choose one, depending on the weather in the marathon race.
  4. Pay attention to the decrease in weight: If human weight decreases by 2-3% due to the water loss, exercise capacity and a body’s temperature regulating mechanism will be lowered and the possibility of getting heat strokes will be increased. Japan Sport Association recommend you hydrate yourself properly and the rate of decrease in weight should not be higher than 2%. In your usual training, please be aware of the changes in weight, and increase the intake of salinity just before the marathon race.

Oral Rehydration Therapy

Taking sport drink is effective as a prevention of heat strokes, but in case of suffering from a light or moderate dehydration, taking Oral Rehydration Solution, OS-1 is suitable. OS-1 has a composition of higher electrolytic concentration than sport drink (Na (sodium): 115㎎ per 100 ml, K (potassium): 78㎎ per 100ml). However, sodium and potassium are relatively high in OS-1, so if you have a chronic disease, please consult your doctor.