Every week, I review the latest sports nutrition and exercise research, looking beyond the headlines to understand what the findings actually mean for athletes. This week, a new review looks at how we could measure and compare the physical work done in CrossFit and other high-intensity functional training workouts.
The study
One of the challenges with CrossFit and HYROX-style training is that no two workouts are quite the same. They combine different exercises, weights, movements, and workout structures, making it difficult to compare how much work athletes actually do.
This review by Mangine, Doese, and Jajtner proposes a standardized way to estimate the mechanical work involved in common exercises.
The authors developed equations using simplified models of human movement, published exercise standards, and average body measurements.
The review covers five types of movement:
- Weightlifting
- Plyometrics (jumping and explosive movements)
- Calisthenics
- Gymnastics
- Monostructural exercise (running, rowing, cycling, and other cardio-machine work)
The authors also provide examples showing how to estimate total work and work rate across sample workouts.
The results
The review provides a framework for calculating positive external mechanical work: essentially, the work your body does to move a weight or move itself through space.
This could give coaches and athletes a more consistent way to compare the physical demands of different workouts.
However, there are important limitations:
- The equations have not yet been validated against direct measurements of force and movement.
- They estimate mechanical work, not the total energy your body uses.
- Metabolic work (the energy your body expends to complete a workout) cannot yet be reliably calculated using this approach.
So, this is a proposed measurement framework, not a validated tool for calculating exactly how demanding a workout was.
Why it matters
In CrossFit and HYROX, it's easy to compare workouts based on time, rounds, reps, or weight lifted. But those numbers don't always capture how much physical work a session involved.
A standardized way to estimate mechanical work could eventually help coaches and athletes compare sessions, track training loads, and make programming decisions with more objective data.
It could also help explain why two workouts that look similar on paper can place very different demands on the body.
My thoughts
I like that researchers are trying to solve a real problem in functional fitness: how do you compare training when the workouts are constantly changing?
But I wouldn't start calculating joules for every WOD just yet. This is a proposed method, and it still needs to be validated.
For now, there are simpler ways to track how training is affecting you:
- Session RPE: How hard did the workout feel?
- Recovery: How well are you recovering between sessions?
- Benchmark workouts: How are you performing when you repeat the same workout under similar conditions?
The goal isn't to collect more numbers for the sake of it. It's to understand your training load well enough to make better programming decisions.
The same applies to your nutrition approach. Don't just add supplements for the sake of it. If you're an older athlete or struggle with recovery, taking HMB daily can help. If your conditioning includes longer, harder efforts, then dietary nitrates like a beetroot juice shot 2–3 hours before can help.
It's about systems, not stacks.
