Crossfit has become immensely popular in the last 5 years, with several million participants and over 10,000 Crossfit affiliates.  The exercise science and research community has been slow to respond to this trend and is just now starting to publish research that examines what factors are related to Crossfit-style training.  In this article, we will look at which factors the exercise science community has traditionally associated with fitness, and what factors matter most for those excelling in Crossfit.

Crossfit is defined as exercise at high intensities across broad time and modal domains.  I’ve always thought this sentence was as clear as mud so lets make it a little more accessible.  Crossfit is defined as activity at high intensities across various types of exercise: lifting, running, gymnastics, olympic lifting, etc.

These types of exercise have been around for awhile, but Crossfit’s real innovation was combining them in such a way that would increase fitness in all areas, not one narrow domain.  Traditionally, if you were a specialist in one of these areas, say, power lifting, for example, you would produce very high 1 rep max squat, bench, and deadlift numbers, some outrageously high.  See the video below showcasing a 1026 lb raw squat.

Now Eric Lilliebridge is perhaps the strongest squatter in the world, but if you’d ask him to run a half mile you’d see soccer mom’s passing him because he is so specialized in his domain.  Crossfit’s goal has been to specialize in all domains, but this leads to an interesting problem. How do you train for everything? What factors matter most?

Most Crossfiters would tell you that the WOD (workout of the day) always leaves them gasping for air, muscles burning, making sweat angels on the floor.  As a consequence you might think that aerobic ability would be key for Crossfit.  Well, you’d be wrong.  What about anaerobic ability producing even more power in the absence of oxygen?  Nope, only indirectly related.  So what matters most?  Drum roll please…….absolute strength.   Outrageous!  Crazy!  I don’t believe it!  Let’s examine the evidence.

Study 1

This study was interesting for a variety of reasons.  First, they recruited very high level Crossfit athletes.  All had participated in the Crossfit open (an annual online Crossfit competition with over 200,000 participants) and some having done well enough in the open to move on to their respective regional competition, putting them in the top .2% of Crossfit Athletes.  See the table below for characteristics.

Particpant Characteristics

These 14 CrossFit Open or Regional athletes completed, on separate days, the WODs “Grace” (30 clean and jerks for time), “Fran” (three rounds of thrusters and pull-ups for 21, 15, and nine repetitions), and “Cindy” (20 minutes of rounds of five pull-ups, ten push-ups, and 15 bodyweight squats), as well as the “CrossFit Total” (1 repetition max [1RM] back squat, overhead press, and deadlift), maximal oxygen consumption (VO2max), and Wingate anaerobic power/capacity testing. The VO2 max test is performed on a treadmill that increases in speed and incline as time goes on, while measuring oxygen usage rate with a face mask.  The Wingate test measures anaerobic power with a 30 sec all out sprint on a stationary bike. See table below for performance on these tests.

Experienced Crossfit Performance Data

The researchers determined that while anaerobic capacity and VO2 max were related to Crossfit performance, they were not predictive of workout outcomes.  Only whole body strength could predict performance in both Grace and Fran.  Strangely enough, they found no significant predictor for Cindy. See Charts below.

CFT and Grace chart


CFT and Grace



Now we can see that Crossfit Total has a huge impact on both Grace and Fran.  Basically, the higher your total, the stronger you are, and the quicker you can complete these workouts.  Anecdotally, this fits with what I have seen in various Crossfit gyms.

I’ve seen tons of folks come into the gym with many different workout backgrounds.  The people that generally do the best for first time Crossfitters are always those with a significant strength backgrounds.  I’ve yet to see a very good endurance athlete do well their first time.  So we know that strength matters for experienced Crossfitters, but does this hold true for novice Crossfitters?

Study 2

This study compared physiological markers and actual workout experience for Experienced Crossfitters and people that had never participated in Crossfit, or Naive Crossfitters as they are labeled in this study.  See table below for characteristics

Naive Experience Crossfit Characteristics

This study had them complete standard V02 max tests and anaerobic power tests as the previous study did.  All participants were males and the Experienced group contained some regional level athletes as well as athletes who had competed in local competitions.  The Naive group had not participated in Crossfit previously, but based off of their physiological markers they were recreationally active.

The first WOD they completed was an AMRAP (as many rounds/reps as possible) in 12 min of 12 Wall Balls, 10ft target with 20lb ball, 12 Swings with 35lb kettlebell, 12 Burpee pull ups.  Workout two was 21-15-9 of sumo deadlift high pull, 24in box jump, and a 40-meter farmer’s walk gripping two 45lb bumper plates. Researchers used the same Wingate and VO2 max protocols described above to measure oxygen usage and anaerobic power.


As you might imagine, the Experienced group did much better on both workouts and had better physiological markers.  However, there was only one physiological marker that predicted performance in both groups, maximum oxygen usage rate, or V02 max.  Surprisingly enough, the anaerobic power, Wingate Test, was not associated with Crossfit performance.  See chart.

V02 and Crossfit


As study 1 pointed out, there was a strong relationship between VO2 max and Crossfit Performance; however, it was not as strong a relationship as overall strength was.  Study 2 seems to demonstrate that V02 is a much better marker of Crossfit performance than anerobic power as measured in the Wingate Test.  I believe that these results are somewhat skewed due to the workouts they chose to study.  These two WODs are very light weight by modern programming standards and would not require a huge amount of strength to complete.  They also included a farmers walk gripping 45lb plates which is almost exclusively a measure of pinching grip.  This should not have been tested as it is too specialized to predict general Crossfit performance. So it seems that the real take away from study 2 is that light weight workouts require a higher V02 max to complete successfully at all experience levels.

Now that we know what markers are associated with those who are participating in Crossfit, what kind of improvement can we expect in these important measures of performance.

Study 3

Participants in this study underwent 6 weeks of Crossfit Training.  They were recreationally active, college age males and females, with no previous Crossfit experience.  See table below for characteristics

Crossfit Improvements Personnel Characteristics

The researchers measured numerous variables, including: 500m row, 1 rep maxes, Fight Gone Bad, Max height jump and various physiological factors.  See chart for details.

Crossfit Newbie Improvement

 This study was quite comprehensive, measuring numerous factors.  It should be noted that these values are averages for the 8 women and 4 men.  This shows that in just a month and a half, these participants lost 3% bodyfat, maintaining their weight which means they actually lost fat and gained muscle at the same time, 6lbs of muscle brah.  Their strength markers increased approximately 12% and their anaerobic conditioning values increase a whopping 25%-31%.


This research demonstrates that there is a lot of room for improvement for those new to Crossfit.  Anecdotally, most experienced gym members would call this beginner gains, but whatever you call it, it’s still impressive.  This data shows not only that concrete performance markers can improve, but so can other factors related to disease, such as high blood pressure, obesity, etc.


The studies that we examined provide us with an invaluable insight into what previously was unverified gym knowledge.  We have seen that, due to the varied nature of Crossfit,  a variety of factors can have a significant impact on performance.  We further have verified that absolute strength is the key factor for those looking for improve their Crossift scores.  Likewise, anaerobic power and VO2 max seem to be relevant depending on the type of Crossfit task being accomplished.

Physiological Crossfit Factors

Training Recommendations 

Based upon the findings in these research papers we, as Crossfitters, should place emphasis on developing maximal strength levels first.  The next order of business would be to develop our anaerobic energy system, as this will bleed over to our cardiovascular system without having to spend huge amount of time participating in aerobic only activities (jogging bleh).

Remember that this is advice is directed at your average Crossfit Athlete.  If you are already very strong i.e your Crossfit Total is 1200lbs or more, you should not waste your time trying to get a 1250lb total as that will take a huge amount of time away from developing your weaknesses.  Likewise, if you are a good runner or swimmer, you would be better served not to practice things you are already good at.  If you want to excel in Crossfit shore up your weaknesses.