Is your training working? (Part 3: Metabolic testing)

Full disclosure: Metabolic (MET) testing isn’t particularly pleasant. You progressively increase your work intensity (on the bike, treadmill, or erg) while breathing into a mask. But the information you receive in return is gold: a snapshot into how cleanly and efficiently your body burns fuel.

Over the next two weeks, we’ll look at different athlete profiles, their MET testing results, and how those results were utilized to individualize the athlete's training and nutrition.

Athlete profile #1:  
Female, Cat 1-2 cyclist, mid-30s (Yes, this is me. Of course I'm going to test this on myself before encouraging others to try it, that's only fair). 


A healthy eater overall, but often craves sugar, chocolate and appreciates a tasty beer after work. Over the last six months, she’s experimented with reducing gluten and wheat from her diet while increasing intake of healthy fats and proteins (side note: she’s experienced significantly less joint pain since this dietary change, and recovers more quickly from workouts). Average carbohydrate intake averages between 1-2 cups of nutrient dense carb per day, in addition to as many veggies as she can possibly consume. Protein and fat intake is primarily from pasture-raised meat and diary, or cold-water fish.  

This athlete has a history of over doing it from time-to-time. Because of this, she has been uneasy about high volume or high intensity training for risk of overdoing it again. 

Here’s a look at the rest results:


The good news:
This is a healthy profile. You can see that her “crossover” point (the point at which she starts burning more carbohydrate than fat) is far to the right. That means she’s an efficient fuel burner, which is not surprising given her healthy eating habits. With this profile, she is able to work all the way up to a moderately high intensity without tapping into precious (and limited) carbohydrate stores. She’s an efficient, clean burning engine.

The bad news:
Her ceiling for high intensity work is low. Once she crossed over into primarily carb-burning metabolism, her rate of perceived exertion and heart rate elevated rapidly, and she didn't last long before having to terminate the work.

What we learned:
This athlete needs high intensity interval workouts to raise her tolerance for high intensity efforts and race pace work. But remember her history of overdoing it? This is where the testing data is a gold mine: we now know the exact wattage and heart rate where this athlete needs to work; by dialing in her interval training to just under her crossover point, we can progressively elevate her tolerance for hard work, without risking overworking her.

Exercise prescription:
The work: “MEP” intervals 1-2x per week at a wattage just under her MEP crossover point. Starting easy with 2-5 minute intervals, then extending that interval time through the weeks up to 20-minute intervals. 

Rest intervals: 2 minute R/Is to begin with, bringing her HR back down to an efficient, fat-burning intensity. 

Total volume of work: because this athlete has overdone it in the past, we need to test the waters to see how her body tolerates this moderately high intensity work. We’ll start with just 20-30 minutes of work at the MEP point, then gradually increase that volume through the weeks, up to 60 minutes or more. 

To wrap up this series, we'll look at two more athletes profiles to show just how real metabolic testing gets real with you if your daily nutrition is not meeting your body's needs.