3 Keys to Better CrossFit Endurance

Going to the gym day after day and doing a 1-hour high-intensity class is great, as long as it aligns with your goals. In this case, you’re going to burn calories, get fit, improve heart health, and build some muscle, for example – in other words, a lot of the standard benefits of training. 

However, if your goal is to maximize your fitness for the sport of CrossFit, your focus must be elsewhere. Specifically, it needs to be in three areas: increasing strength, building better endurance, and improving skills (gymnastics, technique, etc.). 

Each one of these can get rather complex, so let’s focus on one at a time: building better endurance for the functional fitness athlete. 

As the name implies, your base is the foundation of your endurance. Here, I am referring to your aerobic fitness or aerobic threshold. In other words, your ability to perform steady-state work, like a 45-minute easy row. 

Your aerobic threshold is the point during exercise at which your body can no longer clear lactate as fast as it is producing it. Below this point, your body can offset fatigue by quickly clearing lactate (zones 1 and 2). The higher your aerobic threshold, the longer you can stay aerobic during higher-intensity workouts–and the longer you can ward off fatigue. This is a very good thing!

The bulk of high-intensity training programs like CrossFit target your fast-twitch muscle fibers. Unfortunately, lactate is cleared mainly by slow-twitch muscle fibers that are developed at slower intensities. 

In summary, the first key to building better endurance for the functional fitness athlete is to build a better base by increasing your total aerobic training time. I refer to this as the 80-20 intensity balance for the CrossFit athlete. You can read more about it here. 

If you don’t want to read the full article, here is the most important snippet: 

For most CrossFit athletes, I recommend, at minimum, a 60-40 intensity balance. That means 60% of your total non-strength training should be done at Zone 2. The remaining 40% will be done at higher intensities. The higher your total training volume, the higher the Zone 2 percentage should be, up to the aforementioned 80-20 intensity balance.

2. Train All the Movements, But Focus on Your Weakest

One thing we know about lactate production is that different muscle groups have different lactate threshold levels. So, for example, the time to fatigue in air squats might be very different than the time to fatigue in push-ups (although this is just an example, it’s probably true for most athletes as upper body muscles generally produce higher levels of lactate). 

The main point, however, is that different muscles fatigue at different rates–and although some generalizations can be assumed (like upper vs lower body), this is in large part dependent on the individual. 

In the sport of CrossFit, through repetitive practice of the same exercises, most individuals probably have some idea of the exercises that fatigue them the quickest (be wary- I’m not referring to which exercises you find the most challenging, but which ones bring the onset of fatigue the quickest). Those are the exercises that need the most attention and should therefore be programmed into your training more consistently. To reiterate this section’s heading: train all the movements, but focus on your weakest. 

I’m speaking specifically of movements, but I am also referring to specific muscles. One could, for example, conclude that a greater portion of their training should be focused on running, quad-specific exercises, and upper-body pushing exercises.

In summary, aim to raise the lactate threshold of the muscle groups/exercises that most quickly bring about fatigue.

3. Get Strong

You might be wondering, what does strength have to do with building better endurance? Well, for the functional fitness athlete, it’s imperative!

 A few studies, including this one, have shown that independent of other endurance gains like increases in VO2 max, strength increases improve endurance–significantly! 

 Now, truth be told, there are some studies out there that have come to the opposite conclusion (that strength gains do not improve endurance or, if they do, they have a small effect). However, keep in mind that all of these studies are testing pure endurance athletes like cyclists, runners, and swimmers, for example. 

CrossFit, on the other hand, is a sport where your strength endurance is directly tested. Therefore, whether or not strength gains directly affect your lactate threshold levels, it definitely indirectly affects them. 

 The stronger you are, the more strength reserve you have in a workout. The more strength reserve you have, the longer it’ll take a particular muscle to reach its lactate threshold. 

 Read more about the importance of strength reserve here.

 It’s a pretty straightforward assumption: if a workout calls for deadlifts at 185lbs, and your max is 200lbs, you're going to fatigue quicker than if your max was 300lbs–all other things equal. 

Conclusion

To wrap things up, for the functional fitness athlete, building better endurance is key to improving performance. To do this, focus on building a better aerobic base, train your ‘weakest’ movements/muscles, and get stronger overall. A true training plan should involve focusing on each of these things during different times of the year. For example, during the early stages of the year focus on your aerobic base. Then, take some time to focus on your strength. Finally, as you become more specific with your CrossFit training later on in the training year, up the total training time spent on your weakest movements/muscles during your high-intensity workouts.

Good luck & happy training!