06/08/2026
“I run five days a week. My heart rate is great, and my weight is under control. Why would I need to change anything?”
I’m not here to tell you running is bad. It’s not. But let me ask you something: when you say your heart rate is great, what are you comparing it to? Because cardiovascular health isn’t one number; it’s a full picture. And if the only thing you’re training is your aerobic system, you’re getting one piece of that picture. A pretty good piece, sure. But one piece.
“What am I missing?”
Your body has three ways to produce energy. The phosphagen system for short explosive efforts, the glycolytic system for moderate-intensity work, and the oxidative system for sustained aerobic efforts like your runs. Most people think “cardio” means training the third one. CrossFit trains all three. If you’re only running, you’re only training one energy system, and the other two are quietly deteriorating…
See you in the gym…
