One day, Santi, co-founder of Alfa Humans, decided to take a cold-plunge while wearing a BPM (heart rate) monitor. Before getting in, the monitor showed 94 BPM, as he had just finished running. Once inside, after two minutes, his heart rate dropped to 63 BPM.

Why did his heart rate drop so much? In this article, we’re going to explore what happens to the heart during an ice bath session, what the cardiovascular benefits are, and who should avoid it.

What Is Cold-Plunging and How Does It Work?

Cold-plunging is a practice in which the body is submerged in very cold water for a short period of time. In general, this practice is performed with water temperatures between 13°C and 3°C, for 2 to 5 minutes, depending on the individual’s level of adaptation and experience.

Why do people take ice baths? There are many benefits this practice offers for both body and mind, including:

• Faster muscle recovery

• Reduced inflammation in the body

• Increased energy

• Less stress and anxiety

• A stronger cardiovascular system

Let’s dive deeper into this last benefit.

What Happens to the Body and the Heart During An Ice Bath?

The moment we immerse ourselves in cold water, the body generates an instant reaction known as the fight-or-flight response: adrenaline is released, and the blood vessels in the extremities constrict to preserve heat in the core of the body (where the vital organs are located).

You’ll feel your heart beating fast and strong. This is normal because both adrenaline and vasoconstriction increase blood pressure.

Tip: The key is controlling your breathing: inhale slowly through the nose and exhale deeply through the mouth. This helps reduce the impact of the initial shock.

After the first minute, the heart shifts rhythm thanks to two physiological mechanisms:

• Diving reflex: When the body is submerged in cold water (especially the face and neck) this reflex is activated, causing the heart to beat more slowly to conserve oxygen. This is an evolutionary adaptation that helps mammals survive in cold and submerged environments.

• Vagal response: Cold exposure stimulates the vagus nerve, which reduces heart rate and promotes a state of relaxation. This is part of the parasympathetic response.

Conscious breathing also helps shift focus away from the cold, calm the mind, and slow the heart rate.

What Are the Benefits of Cold-Plunging for the Heart?

Changes in blood flow cause the heart to pump more forcefully and help blood circulate more rapidly, becoming enriched with oxygen and nutrients. When you get out of the cold water, that enriched blood flows throughout the entire body.

As a result, cellular metabolism improves, promoting more active cell growth and better organ function, which in turn has a positive effect on the immune system.

In the words of Wim Hof:

“When you go into the cold, you train the circulatory system—the cardiovascular system. Oxygen, vitamins, and minerals reach the cells much better, and therefore, you get much more energy.”

Other cold-plunging benefits that indirectly influence heart health

• Lowers cortisol levels. Chronic stress is a major contributor to heart problems by increasing blood pressure, inflammation, cholesterol, and triglycerides. Cryotherapy is a powerful tool to reduce stress both immediately and long-term.

• Improves sleep. Just 3 minutes of cryotherapy early in the morning can help regulate the circadian rhythm—our internal biological clock—which leads to better sleep.

• Reduces inflammation, one of the main factors that lead to various health issues.

• Improves mental health. As internal body temperature decreases, the body releases endorphins, dopamine, and serotonin, chemicals that play a key role in emotional well-being, pleasure, stress relief, and pain reduction.

Is Cold-Pluning Safe?

Cold-plunging is safe and beneficial when performed in a controlled manner. However, it’s true that not everyone can or should do it.

It is specifically contraindicated for people with heart-related conditions such as arrhythmia, coronary artery disease, hypertension, or other cardiovascular diseases.

Why? Exposure to cold triggers vasoconstriction, sudden changes in heart rate, and an initial increase in blood pressure. In healthy individuals, this acts as cardiovascular training, but in people with underlying health conditions, it may be overly demanding and stressful for the heart.

Anyone who wants to begin this practice—especially if they have any type of illness or condition—should consult their doctor without exception.

Conclusion: Is Cold-Plunging Worth It for Heart Health?

Regular ice baths strengthens the heart and cardiovascular system through vasoconstriction, vasodilation, improved blood flow, and heart rate regulation. However, like any hormetic stress tool, it requires progression, control, and responsibility.

These are our four golden rules when cold-plunging:

1. Don’t push yourself too far—not with time, temperature, or frequency.

2. Listen to your body at all times.

3. Focus on your breathing.

4. It should be a beneficial tool that supports you, not something that harms you or feels unbearable.

Disclaimer: This article brings together information from various professionals and scientific publications, but it should not be taken as medical advice. Always consult a healthcare professional before engaging in cryotherapy, sauna, or any wellness practice.

Want to cold-plunge at home? Alfa Humans Ice Baths feature both cold and heat modes, can be controlled from an app, and are easy to assemble in any space. They’re ideal for those seeking recovery, energy, and wellness from home.