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Coach Justin "Mertz" Mehrtens

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July 21, 2025

Intensity vs Efficiency: Case Study from Novice to Prescribed

Hi there, I am your lone case study, Mertz. This is my record of the trials and tribulations of growth from an intermediate athlete to advanced, and the pitfalls of intensity vs efficiency. During this blog I will show my experience of what it takes to go from recording your scores as Intermediate to Rx and the absolute best way to get there.

Early on in my CrossFit journey, I looked up to the Rx athletes doing their ring muscle-ups & slinging heavy barbells, probably just like you. I was self aware that at that moment I couldn't do what they were doing, but I knew I would be that Rx athlete eventually. Now, “my” eventually meant I wanted it sooner rather than later. I would torture myself trying to push harder & heavier to get to that point.

Rich Froning is a 5 time CrossFit games champ that ruled the CrossFit Games during the years when I first walked into a CrossFit box. I emulated him to a point that I grew a beard, wore the long lifting shorts, and threw on a Rogue “Junk” headband. Hell, I even started going bald on the top of my head to be like him! I’m not saying I had the grandeur of winning the CrossFit games, but I knew that in order to be top of my box I had to replicate what the top dogs were doing.

Now what did that mean for my development as a hard headed, ego lifter? Trouble. Sure coaches would tell me to lighten the load, mainly because my form was shit. What I heard was “take a few pounds off and try again.” Keep in mind, my form was probably still shit, but it allowed me to move a bit faster. Coaches 15 year ago were really at a disadvantage compared to today’s coaches. And now we can find YouTube videos and mentorship programs to help develop us. For the most part all we had was mimicking our own coaches, who had faults that we didnt even know about at the time.

The Level 1 Seminar teaches us the groundwork of the CrossFit methodology. During this two day seminar, there is a lecture about how an athlete progresses in a particular movement. First, teach sound Technique, second is showing Consistency, and third is bringing the Intensity, in that specific order. I would love to tell you I knew to a T what those 3 phases looked like after I took the L-1, but coaching is an art form that takes years to truly understand at depth.

Knowing and understanding are two totally different things. I know that E=mc2, but I don't understand it. New coaches have to develop their understanding well after taking their L-1. Continuing education courses, reaching out to seasoned coaches to talk shop, and reading literature are all great ways to better understand the physiology of the human body. Even then it takes years to develop the understanding of the nuts and bolts, like VO2 max, lactate threshold, biomechanics, anatomy, etc.

Now I know technique is important and intensity is the biggest driver of adaptation.

However, Moving faster with bad form is worse than moving slower with good form. Your bodywill build that into a habit, and a bad habit is hard to break. Eventually you will hit a plateau that seems insurmountable because you are trying so hard your body can't take the volume.

That bad habit and lack of developmental skill work will break something in your body.

That usually looks like tendonitis, inflammation, joint pain, which could develop into arthritis, and worst case Rhabdomyolysis. Rhabdo is muscle tissue that breaks down to a point where your blood becomes toxic and damages the kidneys.

I am dealing with those past bad habits today with different types of injuries that I want to save you from. This is the crux of why we, at X7 CrossFit, teach good movement standards and correct you. It's not to limit yourself, but to limit the injuries that bad movement will cause. Now good movement also pairs well with a nice glass of movement efficiency.

Efficiency is defined as “the state or quality of being efficient: greater energy efficiency.”The key word is energy. The more efficient we perform the movement, the less energy our bodies use. As we hone our skills and by listening to the coach correcting our forms is the healthiest way to eventually perform the workout as prescribed and mark “Rx” next to our scores.

Also once we are able to start writing Rx on the board, that doesn't mean we are done with the skill work that brought us there. That skill work laid the foundation of your body movement and to become more efficient in a higher skill movement, one must become more efficient in the skill work.

After this many years in the biz, I still unlock new ways to move more efficiently. Whether it's on a barbell, a rig, rings, or even on the rower. Learning how to use less energy is the art of body awareness that can be harnessed by doing what 2 things? SKILL WORK and LISTEN to your coach! Mastery in the craft of CrossFit relies on training these undervalued “sub” movements. And guess what happens when you become more efficient in your movement?

More intensity! Which equals better fitness!

F=I (S+E) ; Fitness = Intensity x (Skill work + Efficiency)

Coach Justin “Mertz” Mehrtens CF-L3 USAW