Heat and Venous Circulation: Why Do Your Legs Suffer More in Summer?
When temperatures rise, many people experience a sensation of heavy legs, swollen ankles, or tension in their calves. For patients who already have venous fragility, summer can even worsen certain symptoms or make varicose veins more visible.
But why does heat have such a significant impact on venous circulation? And what simple measures can help relieve leg discomfort during periods of intense heat?
Dr. Paul Pittaluga sheds light on the subject.
Why Does Heat Affect the Veins?
The role of the veins is to carry blood from the legs back to the heart. This venous return works against gravity and relies on two essential mechanisms: the venous valves, which prevent blood from flowing back down, and the calf muscle pump, activated when we walk.
When it is hot, the body naturally tries to regulate its temperature. To do so, the blood vessels dilate — a process known as vasodilation.
This phenomenon is normal and useful for dissipating heat. However, in the legs, it can also make venous return more difficult. The veins dilate, blood flows upward less efficiently, and has a greater tendency to pool in the lower limbs.
It is this pooling that can cause the sensation of heavy legs, swelling, or tension.
Why Do Legs Feel Heavy in the Heat?
The sensation of heavy legs is one of the most common signs of impaired venous return.
Under the effect of heat, the veins relax and dilate, and the valves become less effective at holding blood back. Blood has greater difficulty travelling upward to the heart, especially when one remains standing or seated for extended periods without moving.
This impaired circulation can lead to:
- a feeling of heaviness in the legs;
- swelling of the ankles or feet;
- tension in the calves;
- cramps, particularly at the end of the day or at night;
- a sensation of warm or painful legs.
These symptoms are often more pronounced at the end of the day, after prolonged standing, or during episodes of extreme heat.
Can Heat Worsen Varicose Veins?
Heat does not directly cause varicose veins in a person whose venous system functions normally.
However, it can reveal or exacerbate an already existing venous weakness.
In predisposed individuals, the veins sometimes struggle to return to their normal diameter after dilating. When the valves function less effectively due to venous dilation, le sang peut refluer vers le bas et augmenter la pression dans certaines superficial veins. Over time, these veins can become more visible, more dilated, or more uncomfortable.
This is why some people feel that their varicose veins “stand out” more in summer. In reality, heat exacerbates an already existing or latent venous disorder.
Why Do Ankles and Feet Swell in Summer?
Swelling of the ankles and feet is common when the weather is hot.
Heat promotes vessel dilation and slows venous return. Fluid then tends to accumulate in the tissues, it can often no longer be reabsorbed by the lymphatic system, notamment au niveau des parties les plus basses du corps : les pieds, les chevilles et parfois les mollets. This is what is commonly referred to as “water retention.”
This phenomenon is often worsened by:
- prolonged standing;
- long journeys by car, train, or plane;
- a sedentary lifestyle;
- insufficient hydration;
- wearing clothing that is too tight;
- pregnancy;
- pre-existing venous insufficiency.
Moderate swelling at the end of the day may be benign. However, if it becomes significant, painful, asymmetric, or recurrent, it is advisable to seek medical advice.
Who Is Most Susceptible to the Effects of Heat on the Veins?
Anyone can experience venous discomfort in very hot weather. However, certain people are at greater risk:
- individuals with a family history of varicose veins;
- patients who already have venous insufficiency;
- pregnant women;
- people who are overweight;
- people who stand on their feet all day at work;
- people who remain seated for long periods;
- older adults;
- patients who have previously had phlebitis or venous thrombosis.
In these individuals, heat acts as an aggravating factor. It should not necessarily cause alarm, but it should encourage the adoption of good preventive habits.
Heat, Dehydration, and Circulation: Why Should You Be Vigilant?
When the weather is hot, the body sweats more. If hydration is insufficient, the blood can become more concentrated and circulate less easily.
In predisposed individuals, dehydration can promote venous stasis, meaning the pooling of blood in the veins. This can worsen the symptoms of venous insufficiency and, in certain specific cases, contribute to an increased risk of venous complications, particularly phlebitis.
The aim is not to cause alarm, but to emphasise that adequate hydration is essential for maintaining smooth blood circulation, especially in summer.
Dr. Pittaluga’s Tips for Protecting Your Veins in Hot Weather
A few simple measures can help limit the effects of heat on venous circulation.
1. Walk Regularly
Walking activates the calf muscle pump. With each step, the muscles compress the deep veins and help blood travel back up to the heart.
Even a few minutes of walking (15-20 minutes minimum) several times a day can improve venous comfort.
2. Avoid Prolonged Immobility
Remaining standing or seated for long periods without moving promotes the pooling of blood in the legs.
When working at a desk, working from home, or on a long journey, it is advisable to stand up regularly, take a few steps, or perform ankle flexion-extension movements (rising onto the tips of the toes).
3. Cool Your Legs
Cool water causes blood vessels to contract and can quickly relieve the sensation of heavy legs.
Running cool water from the feet up to the knees at the end of a shower is a simple and effective habit to adopt during summer.
4. Elevate Your Legs at the End of the Day
Elevating the legs for a few minutes helps facilitate blood flow back to the heart.
This can be particularly useful in cases of ankle swelling or a sensation of tension after a hot day.
5. Stay Well Hydrated
Drinking regularly throughout the day helps maintain good blood fluidity.
It is best to avoid excessive alcohol consumption, which promotes dehydration and vessel dilation.
6. Avoid Direct Sources of Heat
Very hot baths, hammams, saunas, prolonged sun exposure, and hot wax hair removal can all exacerbate venous dilation and should be strictly avoided.
In people suffering from varicose veins or heavy legs, these situations can worsen discomfort.
7. Wear Appropriate Compression Garments if Necessary
Medical compression can be very beneficial for people with known venous insufficiency, varicose veins, or significant symptoms.
It mechanically assists blood in returning to the heart and limits pooling in the legs.
However, it is important to choose a compression level suited to one’s individual situation, ideally following medical advice.
Should You Stop Exercising When It Is Hot?
No — physical activity remains beneficial for venous circulation.
Walking, swimming, cycling, or running done in moderation all stimulate venous return and maintain the muscle pump.
During periods of intense heat, it is simply advisable to adapt your exercise routine:
- avoid the hottest times of day;
- favour the morning or late afternoon;
- reduce your effort level during periods of extreme heat;
- stay well hydrated;
- avoid excessively intense exertion;
- wear sport-appropriate compression garments au sport if they have been recommended.
Swimming is particularly beneficial, as it combines muscular activity, the coolness of the water, and natural pressure on the legs.
Which Symptoms Should Prompt a Medical Consultation?
Certain symptoms should not be dismissed, especially if they persist or worsen during summer.
It is recommended to seek medical advice in the event of:
- frequent heavy legs;
- visible or painful varicose veins;
- significant swelling of the ankles or calves;
- persistent pain in one leg;
- a localised sensation of warmth along a vein;
- redness, pain, or hardening of a vein;
- a personal or family history of phlebitis;
- symptoms that recur every summer.
A venous assessment, in particular by Doppler ultrasound, makes it possible to accurately evaluate venous function and propose appropriate management.
