Specialist Doctor I Nguyen Thi Hai, from the Department of Cardiology at Tam Anh Cau Giay General Clinic, explains that when ambient temperatures rise, the body dilates blood vessels and increases blood flow to the skin to dissipate heat. This causes the heart to work harder. Many poor habits can increase the risk of low blood pressure, arrhythmia, and myocardial infarction, especially in older adults and those with underlying cardiovascular conditions.

Drinking too little water

Many people only drink water when they feel thirsty, yet the sensation of thirst often appears later than the body's actual need. The thirst reflex typically diminishes with age.

In hot weather, the body sweats profusely. Insufficient hydration leads to dehydration. This reduces circulating blood volume, forcing the heart to beat faster to maintain blood flow to organs. This condition also thickens the blood, increasing its viscosity and creating favorable conditions for clot formation. For individuals with coronary artery disease, atrial fibrillation, or a history of stroke, this factor can increase the risk of acute cardiovascular events such as stroke or myocardial infarction.

Doctor Hai advises adults to drink about 1.5-2 liters of water daily, increasing the amount during hot weather or intense physical activity. Instead of waiting until you are thirsty, you should divide your water intake and replenish it regularly throughout the day.

High-intensity exercise in hot weather

Physical activity is crucial for protecting cardiovascular health, but the timing of exercise is equally important. Exercising outdoors in intense sun and high temperatures can increase the risk of sunstroke, heat shock, and trigger cardiovascular events in individuals with risk factors.

When it is hot, the heart must increase blood flow to the skin while simultaneously meeting the increased oxygen demands of muscles during exercise. This elevates the burden on the cardiovascular system, potentially leading to low blood pressure or heat exhaustion. Individuals with underlying cardiovascular disease may experience angina or arrhythmia.

People should prioritize exercising in the early morning or late afternoon, avoiding high-intensity activity during the hottest period from 10 a.m. to 4 p.m. Drink enough water before, during, and after exercise, and reduce activity intensity when the weather is excessively hot.

Drinking lots of beer to cool down

Alcoholic beverages cause the body to lose more water due to their diuretic effect. Alcohol can also cause peripheral vasodilation, lowering blood pressure and making drinkers prone to dizziness or lightheadedness when standing up suddenly.

Dehydration in hot weather combined with the effects of alcohol increases the strain on the heart, especially in individuals with cardiovascular conditions or those taking medication for high blood pressure. People should prioritize plain water, mineral water, or low-sugar beverages to maintain fluid balance in the body.

Taking a cold shower immediately after sun exposure or intense activity

Many people habitually take a cold shower immediately after being in the sun or exercising to cool down quickly. However, when the body is hot, blood vessels under the skin are dilated to increase heat dissipation.

Sudden exposure to very cold water can cause blood vessels to constrict rapidly, leading to abrupt changes in blood pressure and heart rate, causing lightheadedness, dizziness, palpitations, or chest discomfort. For older adults or those with pre-existing cardiovascular conditions, these hemodynamic changes can worsen symptoms or trigger angina or arrhythmia.

After sun exposure or exercise, you should rest in a cool, airy place for about 10-15 minutes to allow the body to cool down gradually before showering. Prioritize showering with cool or slightly warm water, avoiding immediately dousing your head or body with very cold water.

Suddenly going from an air-conditioned room to hot sun

Rapid temperature changes between a cold environment and hot outdoor conditions force the body to constantly adjust its circulatory system. In individuals with cardiovascular disease or older adults, this adaptation may be less effective, leading to palpitations, shortness of breath, fatigue, or dizziness. In some cases, sudden temperature changes can exacerbate existing cardiovascular symptoms.

Doctor Hai recommends not setting the air conditioner temperature too low compared to the outside environment; an ideal difference is about 5-8 degrees Celsius. Before going out into the sun, spend a few minutes allowing your body to gradually adapt to the ambient temperature.

If symptoms such as chest pain, prolonged shortness of breath, palpitations, dizziness, or fainting occur in hot weather, patients should seek medical attention promptly.

Ly Nguyen