CrossFit Adaptations Part 2- Cardiovascular/ Respiratory Endurance

In this series, we are focusing on the various adaptations one can gain by doing CrossFit workouts. We started last week by talking a bit about the general goal of CrossFit training. You can check it out HERE if you missed it. Today we’re going to cover Cardiovascular/ Respiratory Endurance.

Cardiovascular endurance is the ability of the heart to provide oxygen to the muscles during physical activity for a prolonged period of time. Your heart is a muscle and thus can be trained like all other muscles in the body to adapt to the workload given. If you’ve not worked out in a long time, the heart isn’t strong or efficient enough to power your exertion. That’s why we scale workouts for beginners.

Respiratory endurance is the ability of the lungs to transfer oxygen to the bloodstream while removing carbon dioxide. Again with proper training, your body will adapt to the workload. Over time oxygen and nutrients can be delivered more efficiently while waste products are carried away allowing for more energy and stamina during exercise.

So all together- Cardiovascular/ Respiratory Endurance can be described as the ability of the body systems to gather, process and deliver oxygen to working muscles.

Does CrossFit work these systems? But of course!

A good CF metcon can really get the blood pumping and anyone who’s done Fran can attest to the “Fran cough.” So with CrossFit, we get a mix of heart and lung strengthening work in a short window of time.

But if the workouts are short, what about endurance?

Ahh, good question. What about endurance? Well, you’re likely talking events or tests in the 1 hour+ range, right? And since the bulk of our CF WODs focus around strength training and short (20-30 min or less) efforts, you might think we aren’t training to be able to “go long.”

Nothing could be further from the truth. If we are working hard (75-95% max capacity) in the 5-30 minute range, we’re asking our bodies to get even better at oxygen and blood turnover. Once we’ve done this style of training and adapted to it, we’re quite efficient machines in this regard. Now, if I ask someone who’s been training this way for some time to run a half marathon, I have no doubt they can do it without any additional run training.


You see, in a half they’ll slow down. It’s not a 400m sprint. They naturally have to slow their pace because of the work ahead. So what happens when I take this machine (athlete) who is now very efficient at oxygen/blood turnover and make them slow down? All things equal, they still have a strong heart and lungs. The have superb work capacity. Now they can cruise through 13.1 miles. Will they win the race? Noooo…that’s for the specialists. But can they do it and have fun? No doubt!

Honestly that’s what I believe this training is all about- having the athletic ability to do whatever you want. Want to run a half? Do it! Want to sign up for your first sprint tri? Go ahead! Want to run 223 miles from Austin to Corpus? I’m in!

So until next time, my friends- Get Fit & Have Fun!

About the Author

Dr. Chris Biles, DC is the head trainer and owner of CrossFit Waxahachie. He is a Level 1 CrossFit Certified Trainer and is passionate about all things fitness. He has competed for many years in adventure racing, mountain and road bike racing, and marathons. His main sport now is the new Sport of Fitness- CrossFit.