How High Intensity is Limiting Your CrossFit Potential

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I imagine you are someone that cares about their training, is interested in how it works, and I hope you take a moment to consider this point of view. If you are training for the sport of Crossfit, you are always looking to improve your conditioning, your engine.

You may feel like you have reached a plateau where you are working really hard but not seeing progress***. At this point, many CrossFitters think they are not working hard enough to make progress. It is natural to think more intensity is always the solution. Yet, no one can beat physiology and this high-intensity approach is limited.

Here is an analogy: let us say you wanted to train to run the best 5k time possible. Would you think going out 5-6 days every week, warming up, then running your distance at all-out effort would be a good training plan?

You are probably thinking that it would be very hard to run all-out every day and that even if you tried, after a few days your runs would just be tough and slow. You can probably easily see how you could get burned out or injured doing this too.

To climb the mountain of your potential, you will need to approach conditioning in a very different way. This way is “new” to most CrossFitters but it is the training foundation for all other endurance sports.

In our CrossFit Competition Program, we will be taking a different approach.

Crossfit is a short-end endurance sport. It is an aerobic sport in a vast majority of events. This can confuse some of you, as you know there is plenty of anaerobic work with the all-out intensity and muscular endurance often required. But the reality is that the aerobic system provides most of the energy for efforts lasting beyond 90 seconds and since most Crossfit events are much longer than this – from 7 to 25 minutes – your aerobic system will be a key player.

Unfortunately, there is not any scientific research on competitive Crossfit as of yet. But, we can look to similar time domain sports to see how top athletes actually train. What you see over and over are large volumes of low to medium intensity work to develop the aerobic system, with just a small dose of very hard efforts (often as little as 5% of total training). 

The aerobic system is important and it will be referred to as your “engine”. In order to build a big engine, you cannot do it by going all out every time or even frequently. It is observed by coaches and researched by academics that the aerobic system adapts differently at different training intensities. All of the different aerobic system adaptations are desired if you want the biggest engine possible.

One of the adaptions from proper aerobic system training is Eccentric Cardiac Hypertrophy. This results in the heart pumping more blood with each beat and resulting in greater efficiency. It also develops the vascular network throughout your body to improve oxygen delivery to the muscles.

These adaptations do not happen well at higher intensities. A more common term for this adaption that is used in cycling and running is “base building” . Having a large base allows you to use high intensity methods later on with much better results.

Many Crossfit athletes have never developed their engine in this way unless they did an endurance sport prior to Crossfit. Since your engine can not produce energy at a high efficiency and rate, you are forced into going anaerobic too much and too early in your workouts. The anaerobic system is great for producing power quickly but is not efficient and burns out quickly.

You literally burn out as the acidity rises in your blood, you can not use your muscles, and you have to stop. No one is immune to this physiological eventuality. Not you or Rich Froning are going to prevent this shutdown from happening when you hit the anaerobic burn button too early in a workout.

Medium intensity aerobic work is used to improve the anaerobic threshold (to delay the burn from happening early). This threshold is the divide between humming along in a workout with your engine versus hitting that burn button. As the intensity of an effort increases (and the heart rate rises), there is always a point where the anaerobic systems will have to take over and the burn starts.

If you train correctly, you can improve this threshold and delay it from kicking in too soon. This allows you to go longer and faster in a workout with just your engine and not reach for the burn button.

This is what Rich and CrossFitters better conditioned than you are doing. The major difference between you and Rich Froning’s engine running at 100% is that he will be moving way faster than you. However, the fatigue, perceived effort and discomfort that you and Rich feel are the same!

They are not working harder than you. They are not extending their anaerobic system longer than you can. They are not mentally defeating physiology. Their engine is just more efficient with more output.

If you always train at a high intensity, you will not raise the threshold. Yes, you may make some progress as your system gets better at tolerating acidity, but these improvements are pocket change compared to properly making a bigger engine.

One of the adaptations from high intensity training is your heart walls thicken and strengthen. This is called concentric hypertrophy, and it is an important adaptation. If you train in this method without increasing the size of the heart with lower intensity methods, the heart walls thicken and become more difficult to enlarge in the future. It is like building a powerful but small engine and your capacity will always be limited from that.

Another problem with high intensity training is lactate from high intensity methods can damage or reduce mitochondria and aerobic enzymes. This will limit your long term development. Lower intensity training increases mitochondria and aerobic enzymes in the muscles This is important, as they help you to actually use the oxygen in your blood to increase output.

I know Crossfitters as a rule like to thumb their noses at conventional practices, but you can not deny physiology.

It is easy to believe that established and time-tested training methods do not apply to us because our sport is CrossFit. It is easy to think that because CrossFit workout movements are different from day-to-day that this does not apply to you. But your engine does not care, it does not know the difference between a kettlebell swing or a burpee, and it simply does its job.

Going all-out on workouts week in and week out will take a toll on the body. It is not only taxing on the cardiovascular system, but also the central nervous system, metabolic and hormonal processes, and more. Maximal efforts can be very effective on occasion but should not be overused. 

By the way, elite CrossFit athletes do not do CrossFit. No one is going all-out every time, following the mainpage, or cherrypicking random workouts and hoping to get better. Nearly all of them have a structured strength program and include many workouts at submaximal aerobic levels.

If you are seeing steady progress on your current training program, keep on it. However, if you are not seeing measurable improvement***, feeling worn down from the constant pedal to the floor approach, or developing injuries, there is a way forward.

Our Competition Program will be approaching engine development with the above thoughts in mind. For a more detailed plan for you, contact us for a private consultation.

*** Many CrossFitters do not even realize their conditioning has plateaued. Often, you are not improving conditioning when you PR in a workout with many different movements. It is really just improvements in strength, skill, or experience.

If you really want to see how your engine is doing, look for accurate assessments that actually test your conditioning – 2k row, mile run, 7 min AMRAP Burpees are just a few examples. WODs where strength or skill are not an issue can also be accurate.