Why Scientists Put Vampire Bats on Treadmills (and what it tells us)

You're at a doctor's office for a routine health check. They ask you to hop on a treadmill for a stress test. As the belt starts moving, you feel your heart racing, your breathing quickening, and your body tapping into its reserves: those carbs from your breakfast toast, a bit of fat from last night's burger, all being burned to keep you going.

Now, imagine if it's a vampire bat on that treadmill instead of you. And instead of toast and coffee, its fuel is a belly full of blood. Strange? Definitely. But this isn't fiction. Scientists recently did exactly that - putting vampire bats through treadmill tests to uncover the secrets of how they turn their last meal into fuel.

Spoiler alert: they're a lot better at it than we are.

Why Put a Bat on a Treadmill?

Most of us think of bats as creatures of the air, flitting effortlessly through the night. But vampire bats (Desmodus rotundus) are unique. These small, stealthy mammals don't just fly, they run. Using a curious hop-and-bound gait, they creep along the ground to sneak up on sleeping prey.

Curious about how these bats power their movements, researchers decided to test their metabolism in the most direct way possible: by feeding them a protein-rich blood meal and putting them on a treadmill. If you think your treadmill test was awkward, imagine being a bat, coaxed into running on this strange new device while researchers measure every breath you take. (See the video about the study here: https://www.youtube.com/watch?v=3rPuy2aVYIM)

How the Bats Performed

When you exercise, your body burns through carbs and fats for energy, with only a small contribution from protein. But vampire bats flip the script. After their blood meal, they rapidly metabolise amino acids from the blood (the building blocks of protein), using them as their primary energy source.

In the experiment, bats were fed blood enriched with labelled amino acids, allowing researchers to track how quickly and efficiently these nutrients were burned. Within minutes of feeding, the bats were running on the treadmill, and up to 60% of their energy came directly from the blood they'd just consumed. While you'd be struggling to catch your breath, these bats were turning protein into power with astonishing efficiency.

The Science of Running on Blood

This metabolic trick is a survival necessity for vampire bats, whose diet lacks the carbohydrates and fats that most mammals rely on. Instead, their bodies are fine-tuned to make the most of the protein in blood, a diet so specialised it fuels their ability to run, fly, and survive.

During the treadmill tests, researchers noticed something remarkable. As the bats increased their speed—from a slow walk to a hopping, bounding run—the proportion of energy coming from their blood meal remained steady. Unlike humans, who shift between fuel sources depending on exercise intensity, vampire bats rely almost entirely on amino acids, no matter how hard they're working.

What Can We Learn From Vampire Bats?

For one, their metabolic strategy underscores how diet and evolution shape an animal's biology. While humans have the luxury of a varied diet and energy reserves, vampire bats are living proof of how animals adapt to the most extreme dietary restrictions.

But the experiment also sheds light on the incredible efficiency of these animals. They've evolved mechanisms to digest and absorb nutrients with astonishing speed, turning a fresh meal into energy within minutes. It's a reminder of just how adaptable life can be and how much we still have to learn about the unique metabolisms of other species.

While the image of a bat bounding along on a treadmill might make you smile, the implications of this research are far-reaching. Their ability to rapidly turn food into fuel could help us understand energy use in athletes, improve recovery after surgery, or treat metabolic disorders.

Who'd have imagined that a bat on a treadmill could bring us closer to improving human health?