Crossfit 101: Pros, Cons, and Catchphrases

A deep dive into the good, the bad, the pros, the cons, the science, and the catchphrases of the fitness movement known as CrossFit.

Brock Armstrong
10-minute read
Episode #348

Will it work?

Well, CrossFit does have its plusses for sure. It is fun and satisfying to work that hard and congregating at the Box is a nice way to meet people who have a similar penchant for self-punishment. Plus the workouts are freakin’ tough, involve doing some cool moves, and you will see results if you stick to it.

But I want to dig into a 2009 paper called Molecular responses to strength and endurance training: are they incompatible? from RMIT University, which found “combining resistance exercise and cardio in the same session may disrupt genes for anabolism.” Which is a fancy way of saying that combining endurance and resistance training impaired muscle’s ability to fully adapt to either.

Which is a fancy way of saying that combining endurance and resistance training impaired muscle’s ability to fully adapt to either.

The study also found that doing cardio before resistance training suppressed anabolic hormones such as IGF–1 and MGF, and on top of that, doing cardio after doing resistance training actually increased muscle tissue breakdown.

Several other studies found similar outcomes. A study called Concurrent strength and endurance training: from molecules to man, found that “activation of AMPK by endurance exercise may inhibit signaling to the protein-synthesis machinery by inhibiting the activity of mTOR and its downstream targets.” Other studies from the Waikato Institute of Technology, and the University of Jyvaskyla (Finland), agreed that training for both endurance and strength simultaneously impairs your gains on both fronts.

Does this mean CrossFit won’t do anything for your strength or endurance? Well, no. Any workout with some intensity, combined with the right amount of rest, will certainly benefit your fitness level. But if you truly want to Hulk up (yes, I worte Hulk not bulk), or if you want to really max out your aerobic capacity, science says that CrossFit is not your first choice. Science says that the most effective way to both build strength and improve aerobic endurance is to separate your weight lifting from your cardiovascular exercise.

Now how does CrossFit’s mission statement stack up now? Well, let’s try another rewrite: “The CrossFit protocol can elicit a substantial neuroendocrine wallop if you have the self awareness to push just hard enough and, if done correctly, packs a catabolic punch that elicits an anabolic response that can put on some muscle but not as much as you would if you weren’t also maxing out your cardiovascular system.” Wow! I think I have a hit on my hands.

Back home at the ranch...

A couple weeks have passed now since my first CrossFit workout and I am waiting for an introductory session to start. There is a mandatory 10 class intro period where you learn how to do all of the various workouts safely and effectively. The presence of this mandatory training session again helped allay the injury fears I had for all those years I spent avoiding CrossFit. I had the choice to do the 10 sessions in a one-on-one setting or with a group and I chose the group because sweating your butt off is always more fun with other people - am I right?

In preparation for my sessions, I am studying some olympic lifts and I went out and purchased a jump rope. Embarrassingly enough, doing 100 jumps was the most vomit inducing part of the workout for me. And that will not stand!

Like many things in the fitness world, skipping has a lot to do with efficiency and I was clearly not being efficient. Luckily, humans are masters of efficiency. Due to our inherent laziness (and I don’t mean that in a particularly bad way in this instance) with pure repetition and little else, our bodies will automatically find the most efficient way to do something. So I have been skipping rope a few times a week now and I can nearly do 100 without feeling my breakfast sneaking back up from whence it came.

Since I am more interested in learning something new than I am in bulking up more or ever trying to recreate my marathon PR of 5 years ago, I will go forward with my CrossFit plans and check back in with you once I have a few months of CrossFit under my belt.

My Approach

I have to admit that I am already planning to take more days off than the normal CrossFitter might and if I don’t see the gains I am hoping to, I will likely add in some heavy lifting days. And if my 10k running time starts to falter or my hill climbing ability on the bike starts to wain, I will also add in some sport specific workouts. For those of you who are interested, it will likely look like this:

Day 1: Crossfit + easy recovery run

Day 2: Crossfit + short swim or bike intervals

Day 3: Rest (foam roll or maybe a massage)

Day 4: Lift Heavy (no cardio)

Day 5: Cross fit + easy recovery run

Day 6: long aerobic run or bike + swim drill workout

Day 7: Rest (maybe light yoga)

I will also strive to be the guy at the back of the class who is more preoccupied with form than reps, equally focussed on recovery and WODs, and I plan to never look like the unofficial CrossFit mascot “Pukey the Clown” if I can help it. Given my current jump rope prowess, I make no promises. 

If you are a diehard CrossFit fan or have more questions about whether CrossFit is right for you, head over to Facebook.com/GetFitGuy or twitter.com/getfitguy. Also don't forget to subscribe to the Get-Fit Guy podcast on Apple Podcasts, StitcherSpotify, Google Play or via RSS.


All content here is for informational purposes only. This content does not replace the professional judgment of your own health provider. Please consult a licensed health professional for all individual questions and issues.

About the Author

Brock Armstrong Get-Fit Guy

Brock Armstrong was the host of the Get-Fit Guy podcast between 2017 and 2021. He is a certified AFLCA Group Fitness Leader with a designation in Portable Equipment, NCCP and CAC Triathlon Coach, and a TnT certified run coach. He is also on the board of advisors for the Primal Health Coach Institute and a guest faculty member of the Human Potential Institute.