One of the most serious conditions to watch out for during summer outdoor activities is heat stroke. Heat stroke is an emergency situation that occurs when the body's ability to regulate temperature reaches its limit in high-temperature environments, and appropriate prevention and early intervention can be lifesaving. This article provides practical information on heat stroke stages and symptoms, effective hydration methods, nutritional management, and UV protection strategies.

Stages of Heat Stroke

Heat stroke is not merely fatigue but a progressive condition that develops as internal body temperature rises. In the initial stage, body temperature ranges from 37–40°C and exhibits heat exhaustion, during which the body loses large amounts of fluids and electrolytes through profuse sweating. The second stage, heat cramps, occurs when electrolyte imbalances within muscles cause cramping in the legs, arms, and abdomen.

The most dangerous third stage is heat stroke, where body temperature rises above 40°C and the central nervous system becomes damaged. At this stage, life-threatening symptoms such as confusion, seizures, and cardiac arrhythmias appear. According to statistics, approximately 10–20% of heat stroke patients suffer permanent neurological damage even after treatment, and the risk of death exists without immediate emergency care. This is why stage-by-stage prevention is crucial.

Heat Stroke Symptoms

Initial symptoms of heat stroke begin with lethargy, dizziness, headache, and nausea. Many people mistake these for simple fatigue and neglect them, which is a major cause of worsening the condition. Simultaneously, the skin may become pale or flushed, and a phenomenon called "anhidrosis" may occur where sweating stops.

There are specific groups that require particular attention. Postmenopausal women are more vulnerable to heat stroke because hormonal changes decrease the sensitivity of the body's temperature regulation center. During the luteal phase of the menstrual cycle (the 2 weeks before menstruation), basal metabolic rate increases, which can heighten heat sensitivity. Additionally, children, elderly people, obese individuals, those with cardiac conditions, and those taking antidepressants or antihistamines are considered high-risk groups.

Advanced symptoms include muscle cramps (particularly in the legs and abdomen), rapid pulse (over 100 beats per minute), shallow and rapid breathing, and elevated skin temperature. If confusion or seizures appear, immediately call 911 and seek emergency medical treatment.

Drinking Water and Maintaining Hydration

The most basic yet important method for preventing heat stroke is appropriate fluid intake. Generally, when engaging in activities in heat stroke-prone environments, you should consume 250–500ml of water at minimum every hour. Drinking only when you feel thirsty means you have already entered the initial stages of dehydration, so caution is necessary.

What matters is not just drinking water but maintaining electrolyte balance. Sweat contains not only water but also sodium, potassium, magnesium, and chloride. If you consume too much water alone, "hyponatremia," a condition where blood sodium concentration drops sharply, can occur. Therefore, for outdoor activities lasting more than one hour after exercise, consuming sports drinks (containing 4–6% carbohydrates and 20–30mmol/L sodium) is recommended.

Potassium is an essential electrolyte for water distribution in the body and nerve signal transmission. Foods containing potassium include bananas (358mg per 100g), spinach (558mg per 100g), sweet potatoes (337mg per 100g), and avocados (485mg per 100g). Consuming these foods before and after high-risk heat stroke activities can replenish electrolyte loss. However, those with kidney disease should consult medical professionals before adjusting potassium intake.

Supplementing with Branched-Chain Amino Acids

Branched-chain amino acids (BCAAs) consist of leucine, isoleucine, and valine, and play important roles in muscle protein synthesis and energy metabolism. BCAA supplementation during prolonged physical activity in high-temperature environments helps maintain temperature regulation ability beyond simple performance enhancement.

Research shows that groups supplemented with BCAAs during exercise in hot environments experienced lower central fatigue and maintained work capacity longer than groups without supplementation. This is explained by the mechanism in which BCAAs delay fatigue signal transmission in the brain. The recommended BCAA intake varies depending on exercise intensity and duration, but generally follows the standard of 0.03–0.05g per kilogram of body weight. For example, a 70kg person engaging in outdoor activities in high heat for three hours or more may benefit from consuming 2.1–3.5g of BCAAs.

BCAAs are naturally found in protein-rich foods such as eggs, chicken breast, milk, and tofu. Chicken breast contains approximately 3.5g of BCAAs per 100g, so eating a protein-rich meal before activity is also effective. When taking supplemental forms, verify the purity and safety of the product and choose one appropriate for your individual health condition.

Applying Sunscreen

UV exposure is a direct factor that increases heat stroke risk. When the skin receives UV rays, blood vessels expand toward the skin surface, increasing blood flow for heat dissipation, which interferes with the body's internal heat retention mechanism. Therefore, sunscreen use is an important preventive measure that aids temperature regulation.

The proper method for using sunscreen is as follows. First, choose a broad-spectrum sunscreen with SPF 30 or higher (UVA blocking index PA+++). SPF is a UVB blocking index, and higher numbers provide longer protection, but the actual blocking efficiency difference between SPF 30 and 50 is only 1–2%, so SPF 30 is sufficient. Second, apply adequate amounts to exposed skin areas. Use approximately 1/4 teaspoon for the face, 1/4 teaspoon for the arms, and 1/2 teaspoon for the front of the legs.

Third, reapply every 2 hours, and more frequently if wet with sweat or after entering water. Using water-resistant products (waterproof for 80 minutes or longer) is advantageous during water activities. Fourth, applying sunscreen 15–30 minutes before sun exposure is the optimal method considering absorption time. Chemical UV blockers (oxybenzone, octinocrylene) are absorptive types requiring 15–30 minutes of wait time, while physical UV blockers (zinc oxide, titanium dioxide) are reflective types that work immediately.

Additional preventive measures include wearing UV-blocking clothing (UPF 50+), hats (with brims 7cm or longer), and sunglasses (UV 400 blocking). Combining these physical blocking methods can lower skin temperature by 5–10°C, significantly reducing heat stroke risk.

Emergency Response When Heat Stroke Occurs

When heat stroke is suspected, immediate action is necessary. First, remove the patient from the hot environment and move them to a cool location (air-conditioned indoor space, shaded area, etc.). If the person is conscious and alert, have them drink cold water, but do not give food or beverages if consciousness is impaired or seizures occur.

To rapidly lower body temperature, wrap the body with wet towels or take a cold shower. Apply ice packs to areas where major blood vessels pass, such as the neck, armpits, and groin, for 10–15 minutes. Temperature recovery typically takes an average of 30 minutes. Even if symptoms improve, the person must be examined by a healthcare professional, and especially if consciousness decreases, seizures occur, or abnormal breathing develops, call 911 for emergency room treatment.

Summary

Prevention is the top priority for heat stroke. The most effective prevention occurs when you maintain hydration and electrolyte balance (especially sodium and potassium), manage body energy through protein and BCAA, and use UV blocking for skin heat reflection.

  • Fluid intake: 250–500ml of water every hour; combine with sports drinks for activities lasting more than one hour
  • Electrolyte management: Consume potassium-rich foods (bananas, spinach, sweet potatoes)
  • Nutritional supplementation: Consume protein before activity or supplement with BCAAs (0.03–0.05g per kilogram of body weight)
  • UV protection: Reapply SPF 30 or higher sunscreen every 2 hours; wear protective clothing
  • Emergency situations: Immediately call 911 if confusion or seizures occur

Postmenopausal women, children, elderly people, and those with chronic illnesses are particularly at high risk for heat stroke and require more thorough prevention measures. When planning activities in hot environments, comprehensively considering these factors will allow you to have a safe and healthy summer. Always remember that prevention before symptoms develop is much more effective than intervention after symptoms appear.