The Science of Ultrarunning


This is the first in a series of articles on what happens to your body during an ultra, focusing on the sparse but growing scientific literature that exists. However, physiology is extremely individual dependent, so please interpret this column with caution, as we are all different.

Why Studying Ultra Athletes Is Difficult

I love the science of exercise. My first real experience with this came as a college athlete looking for a competitive advantage to training at altitude. I took a class: Environmental Effects on Human Performance. I was hooked, and have been studying exercise in one form or another for the past 12 years. I am still trying to uncover links between science and performance to find the pot of gold – the most effective training and racing tactics.

If you look through the scientific literature on exercise, you will find study after study with the following subject profile: males 18 to 25 years old. In other words, college students, and not much ultra-specific data.

Fortunately, an ever-increasing amount of research is being performed on ultrarunners and ultra events, in large part thanks to races like Western States and people like Dr. Marty Hoffman who have created a research culture associated with specific races. Still, barriers remain to conducting definitive studies on what happens to our bodies during an ultra. Before we can tackle this fascinating topic, it is useful to understand some of the challenges to sourcing good data.

In a laboratory setting we have easy access to equipment that allows us to immediately freeze tissue samples, spin down blood, evaluate urine samples and make measurements with pieces of equipment that take up entire rooms. In the field we are lucky if we can take blood samples, and even luckier if we can keep those on ice. Throw in elements such as weather, terrain and time commitments, all for science that is very much under-appreciated in our current scientific culture, and you start to understand why we lack answers to some of the most fundamental questions regarding the physiological impacts of ultrarunning.

The Reductive Nature of the Scientific Process

In biology and medicine we are encouraged to eliminate variables so that we can identify the cause of the observations we measure. But can you imagine a study that only allowed people one type of gel, a fixed amount of water or insisted that pace was unchanged for a 100k race?

So instead of manipulating only sodium intake, caloric intake or water consumption, we make measurements of all of those variables (and many more) in as many people as we can with the goal of trying to find relationships or correlations. If we are lucky we might find that one of the variables we measured may correlate with outcomes such as finish time or weight changes. However, we all know that correlation does not equal causation, and thus we can’t know for certain that caloric intake causes improved finishing times. Still, I promise some tangible and concrete takeaways that you will be able to use in your next race.

The Non-Reductive Nature of Ultramarathons

The diversity of ultras and ultra competitors makes the science of ultras even tougher. Think about the finish of Western States in 2015 – the oldest and youngest female finishers in history finished within minutes of each other. They are certainly not having the same physiological responses to the event. Or in terms of diverse courses, think about Hardrock. There is nearly 24 hours between the first and last finisher and there’s a cumulative elevation gain equivalent to climbing Mount Everest. Compare that experience to what someone experiences at a relatively flat 100 miler like Rocky Raccoon.

I helped perform a study that looked at the physiological responses of runners to completing 7 marathons in 7 days, which might not be an ultramarathon, but it certainly qualifies as an endurance event. We found that the runners became faster over the course of the event with relatively low markers of muscle damage. But does that mean an ambitious ultrarunner looking for improvements should run 7 consecutive 100 milers? (The answer for some of you out there possibly cogitating on this is a definitive “no!”)

Still, there are some common denominators when it comes to the cellular and whole-body physiology of running long distances. In some ways stress is stress and the physiological responses to a 100 miler are more similar than the courses themselves.

In the next few issues I will address what we know happens to our bodies at a cellular level in response to extreme amounts of exercise – and offer some science that can actually guide improved training and racing at your next ultra.

A hint – terrain has huge impact on muscle cells.


About Author

Matt Laye has a PhD in Medical Physiology and is an Assistant Professor of Health and Human Performance at The College of Idaho and lives in Boise, ID. He enjoys competing on trails and on the roads in distances from the mile to 100 miles. He has averaged under 8 min/mile for 100 miles and under 5:30/mile over a marathon.

1 Comment

  1. David Pauwelyn on

    What is it about rough terrain that makes it addictive? When I first started running trails it was a bit of a hard slog and I did not enjoy running anything that was too rough or rocky. Now it’s the opposite – I thrive on trails and I am always looking for a challenge. I genuinely get bored if I have to run more than a mile on roads. Great intro and teaser Matt.