Inside the cells of the world’s most endurance-trained athletes

What happens inside the muscle cells of an athlete who runs almost 1,000 miles in sub-zero temperatures?

That question took Virginia Tech doctoral student Pierre-Anne Laird to Big Lake, Alaska, and the home of some of the world’s most extraordinary endurance athletes — Alaskan and Siberian Husky sled dogs.

Laird, a second-year Ph.D. student in the department of Human Nutrition, Foods, and Exercise, traveled to Happy Trails Kennel in January to attend a workshop hosted by the Oklahoma State University Comparative Exercise Physiology Lab and Oroboros. The workshop focused on studying the cellular biology that allows these dogs to perform feats of endurance that would be impossible for most mammals. The workshop experience combined hands-on fieldwork with advanced laboratory techniques, offering insights that may ultimately help scientists better understand how humans adapt to exercise and build resilience.

For Laird, these questions closely align with his doctoral research on how cellular signals triggered by exercise drive long-term physical adaptation.

“Our lab studies the molecular biology of acute exercise — the immediate biological events that happen in the body when we move,” Laird said. “Those early responses are what allow us to adapt over time, improve fitness, and gain the health benefits of regular physical activity.”

Laird’s doctoral work centers on understanding how these early molecular responses translate to meaningful adaptations, and he hopes that studying one of the planet’s most extreme examples of sustained aerobic exercise will ultimately help improve human fitness outcomes. While in Alaska, Laird’s goal was to learn advanced laboratory techniques to better understand the unique biology of sled dogs and how these techniques can be applied to his own research.

And nature has few endurance runners that can match them. Iditarod dogs burn close to 12,000 calories a day and maintain a body heat of 109.4 degrees Fahrenheit, even in temperatures as low as -40 degrees.

“Part of the reason these dogs are such amazing athletes is that their mitochondria are particularly capable of high energy output and can adapt to training extremely quickly,” Laird said. “Studying these extreme performers helps us uncover principles that may translate to human exercise adaptation and health.”

The aim of the workshop was to focus on learning about the mitochondria, the so-called “powerhouse of the cell.” In addition to being energy producers, mitochondria also act as cellular signaling hubs in response to exercise. This signaling role is a key part of Laird’s research, which examines how these signals influence long-term metabolic health.

The researchers used a common method called respirometry to study mitochondria. Respirometry allows researchers to approximate mitochondrial energy production through tracking changes in oxygen level in a tissue using an instrument called an oxygraph. Training in these techniques directly supports the experimental approaches used in Laird’s work in the Craige Lab.

In addition to his hands-on laboratory work, Laird also had the opportunity to get on the sled with the dogs and “mush,” going on several excursions.

“The combination of seeing these mitochondria in action both in the snow and in the lab was an experience I will never forget,” Laird said.

Although sled dogs served as a powerful example of extreme endurance physiology during the workshop, Laird’s research in the Craige Lab is focused on how exercise-derived physiological stress signals drive beneficial mitochondrial adaptations. His work seeks to understand how these cellular responses to exercise support metabolic health. The Alaska experience provided advanced training in techniques and concepts that directly inform this ongoing research in the Craige Lab, working along with the HNFE Metabolism Core.