Muscle Stimuli that CrossFit Misses

I need to be careful. Looking back, it seems that there are many posts that one could construe as me mocking, criticizing, or scoffing at CrossFit. That is entirely not the case.

CrossFit gets a lot of things right. High intensity sheds fat. Using progressively heavier weights builds muscle. Having lots of metrics to focus on so that you always see progress somewhere is what keeps people hooked and happy.

The problem arises when athletes start using CrossFit as the only source of training outside another sport. Or even using CrossFit as their only type of training for CrossFit competitions. CrossFit does have its limitations and not becoming more well rounded in athletic development can lead to not achieving your goals at best, and serious injury at worst.


CrossFit tends to focus almost completely on one form of muscle use: concentric or the contraction phase.

Isometrics are where you hold static muscle tension under load. This one is occasionally touched upon by CF boxes when you have L-sit holds and planks. We often see isolations in core work, like in the previous examples. They gyms I work at also have their athletes practice other holds like partial push-up positions and chin holds.

Using isometrics just gives your training another dimension to help your muscles get stronger. And using them on muscles other than the core would be helpful. If you train for gymnastics at all, you'll see a lot of this for the upper body. I'd recommend visiting GWOD to learn how to implement some into your training.


Eccentric, or the extension phase, is a very important part of athletic development that is almost wholly  ignored by CrossFit. There are a couple of reasons that eccentrics are very important. First, a muscle can actually create more force (in lbs/ during the eccentric phase. That means you can load more weight into a system, cause more of the muscle damage stimuli that increases growth.

This has to be used with caution. It can help with injury prevent, because your muscles and tendons get used to the extra load used in eccentrics (think of how often hamstrings and achilles get injured in various sports). But you can also injure yourself using this. Have you have done a lot of pull ups and had T-rex arms the next day (can't straighten them out)? You can easily and quickly cause enough damage that you can't recover and end up with localized rhabdomyolysis.


When I talk about overload training here, I'm not talking about the go to exhaustion, then do a few more that a typical CF metcon has. Those are about endurance, cardiovascular and strength. I'm talking about methods that quickly allow the body to hit fatigue and do more. Or methods that allow more weight to be put on the system in advantageous strength positions.

For the first, using a combination of concentric and eccentric work, you can hit muscle fatigue in less than 10 reps. Ex: Have a partner push on your back while you do push-ups, and you have to resist on the way down, and push through on the way up. The partner pushes harder during the eccentric (down) phase, and just gives some resistance on the concentric (up). Done properly, the push-upper should reach muscle failure in 6 or 7 reps. Then the partner steps away, the push-upper goes to knees and reps out.

If you've ever dabbled in powerlifting and the Westside Barbell methods, you've probably played with bands, chains, and the Slingshot. These methods allow you to have more weight, either through band tension or Slingshot assistance, in positions where your levers are stronger, ie, past your "sticking points". This stimulus allows your connective tissues and central nervous system to experience heavier weights and can prep them for greater max lifts.


Most CF "kool-aid" drinkers are adamantly against isolations, otherwise known as "body building." I tell people, you know, if you're down with being asymmetric and accruing injuries, that's cool. Sure, doing some isolations can give your appearance a nice well rounded look, but also let's be frank, no one is perfectly symmetrical and as such we are all going to move a little wonky because of it. For instance, I tend to hold weight overhead in my delts, and I need to do extra back work to balance myself out and make sure those muscles and structure keep firing and are there to support me when I need them.

Isolations can also help with injury prevention, particularly when combined with eccentrics. Doing calf raise negatives (hold weight, raise up on an edge with both legs, lower with only one) can helo prevent blown achilles. My elbows hyperextend, so I'm doing extra bicep curls to protect them in ballistic overhead moves. Plus, biceps are sweet.

Partial Reps

This is definitely more of a bodybuilding technique, but it can also just help build foundational size in places like the shoulders and back. CF emphasizes full range of motion in all movements, which in the case of 95% of work should absolutely be the case. However, during the "dessert" part of a person's workout, doing partial reps keeps your working muscles under tension through the entire set, and also gets extra use out of the stretch reflex (alternately knows as the Stretch Shorten Cycle, SSC), a stimulus that promotes hypertrophy.