In 2013, I had the honor of receiving a personal invitation from the Dominican Triathlon Federation to represent the country as an elite athlete in the Olympic circuit. It was an incredible opportunity, but also one of the hardest lessons of my athletic life.

By then, I had spent the winter training in Michigan, my first real triathlon preparation in nearly 15 years; bundled in layers and working within controlled environments. Then, suddenly, I found myself racing an Olympic-distance triathlon at the ITU (Panamerican Cup) in nearly 98°F heat in the Dominican Republic.

I wasn’t adapted. I wasn’t ready.

During the final 10K of the run, everything changed. At around the first 5K, I started to feel dizzy. My body was no longer responding the way I knew it should. Then, I lost awareness. I kept moving, but not consciously, zigzagging, disconnected, running purely on instinct.

I crossed the finish line… and collapsed.

In the medical tent, I remember a deep, overwhelming feeling: I thought I was going to die.

That experience was exertional heat stroke.

What is Heat Stroke?

Heat stroke is the most severe form of heat-related illness. It occurs when the body’s temperature rises above 104°F (40°C), and the body can no longer regulate its internal heat.

There are two main types:

Classic heat stroke: caused by environmental heat exposure
Exertional heat stroke (EHS): caused by intense physical activity in hot or humid conditions

In athletes, it’s almost always exertional.

Why Does Heat Stroke Happen?

Your body constantly tries to maintain a stable internal temperature (~98.6°F). It cools itself mainly by:

Sweating (evaporation)
Increasing blood flow to the skin

But during intense exercise:

Muscles generate large amounts of heat
High temperatures + humidity reduce cooling
Dehydration limits sweat production

When heat production exceeds heat loss, body temperature rises dangerously.

At that point, the system fails.

What Happens in the Body and Mind

Heat stroke is not just “overheating”, it’s a full-body crisis.

In the body:

Core temperature skyrockets (>104°F)
The cardiovascular system becomes overloaded
Cells begin to break down
Organs (kidneys, liver, muscles) can fail
Inflammation spreads through the body

In the brain:

Confusion
Loss of coordination
Delirium
Loss of consciousness

That “out of my mind” feeling I experienced? That’s central nervous system dysfunction, a defining feature of heat stroke.

Why It Happens in Athletes

Athletes are particularly at risk because:

They generate extreme internal heat
They push through discomfort
They often compete in challenging environments
They may not be heat-acclimatized

Heat stroke is actually the third leading cause of death in athletes during physical activity.

In triathlon specifically:

High intensity (especially during the run) increases risk
Events often occur in hot conditions
Dehydration is common

Even elite athletes are not immune.

How Common Is It in Triathletes?

The good news: it’s relatively rare, but not negligible.

About 1.74 cases per 10,000 athletes in triathlon events
Heat-related issues (like dehydration/exhaustion) account for 58–72% of medical cases in long-distance races

However, under extreme conditions or poor preparation, the risk rises significantly, especially early in the season or when athletes are not heat-adapted.