The Science of Endurance

The Science of Endurance

As records were broken and some of the world’s best athletes gave their greatest performances, the Olympic and Paralympic contests this summer reminded us again: humans are built for amazing feats of physical endurance. From Christopher McDougall’s stories of ancient hunters outlasting game animals in Born to Run to today’s endurance champions, the human body is an amazing and efficient machine. With the proper training and maintenance, what athletes can achieve seems almost limitless. But what is it about our bodies that makes us such great endurance athletes? Let’s take a look at the science behind the amazing human machine.

  • Cardiac Contributors – Basically, the more blood your heart can pump each time it beats, the better tuned you are for endurance. The key factor here seems to be the size of the left ventricle—the more blood it can hold, the more blood the heart can pump out and pull in. The great news is you don’t have to be born with a large left ventricle, although that certainly helps. Studies show that endurance training over time can lead to a larger left ventricle. This adaptation is aptly referred to as the athlete’s heart.
  • Muscle Matters – All that blood flow is important primarily because it delivers oxygen to your muscles where it is then used to produce energy and keep those muscles moving. The amount of oxygen distributed to your muscles and how much of that oxygen your muscles can pull out and use determines your VO2max, the best measure of aerobic endurance. There are a few ways to estimate your VO2max, such as this quick method. Here’s the good news: With training and healthy living, your VO2max can be improved over time.
  • Metabolic Mechanisms – Some of the key metabolic factors that drive endurance are the body’s ability remove lactate to avoid metabolic acidosis and the ability to metabolize fat and carbohydrate energy sources. During strenuous exercise, the body can’t remove lactate and other metabolites fast enough, which results in metabolic acidosis, or acid buildup, and that contributes to fatigue. The longer a body can perform at high levels and still dispose of lactate, the longer that body can endure the activity. Another metabolic function that keeps the body going is the body’s ability to extract energy from fat. While our body prefers carbs for energy—they’re easier to burn—fat cells are great for energy storage. While carbs can get your body through a couple of hours of running, you’ve got enough energy stored in fat to keep you going for days! Proper endurance training helps you better access that fat.
  • Sweet, sweet sweat – By the end of a race, you’re drenched in sweat and ready for a shower. But don’t hate on all that sweat too much—it’s what got you to the finish line! In all the animal kingdom, it seems we humans are the best sweaters. Most creatures have to stop and pant to deal with the buildup of heat while running. Humans, however, alter our breathing while we go and sweat from virtually every part of our skin while we run. This sweating and resulting evaporation allow our body to release heat and cool itself efficiently while we keep on going.

As marathon season continues and athletes really begin to target their training routines, the big takeaway here is this: Performance in virtually every metric listed above can be improved with consistent training and healthy choices. Whether you’ll be running in the Chicago, New York, or Philly marathons this year, or any number of other fantastic races, knowing how your body operates as you work toward that finish line is an ace in your training regimen. Join the conversation below. What are you doing to improve in these vital areas? What’s holding you back and how can you adjust to improve performance? We’d love to hear from you. Join the discussion below or join us over on Facebook, Twitter, and Instagram.



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Shalane Flanagan’s Road to Marathon: Read about the Olympians transition from track star to champion marathoner

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