What if the reason you’re slowing down in the final miles has nothing to do with cardio—and everything to do with muscle fibers you’ve been completely ignoring?
What Is It?
Your muscles aren’t all the same. You’ve got slow-twitch fibers (marathon workhorses) and fast-twitch fibers (explosive sprinters). Distance runners lean hard on slow-twitch, but here’s the kicker: research from Dr. Phil Gollnick shows that around 60-90 minutes into a run, your slow-twitch fibers burn through their glycogen stores. When that happens, your body recruits fast-twitch Type 2 fibers as backup. If you haven’t trained them? You’re screwed.
Why Does It Matter?
This is why runners hit the wall at mile 20. Your primary engine runs dry and your backup engine—those fast-twitch fibers—aren’t ready to take over. But train them and suddenly you’ve got a second gear when everyone else is fading.
How To Do It
Three moves, stupidly simple:
- Strength work (2x/week): Squats, deadlifts, lunges. Heavy enough to feel hard.
- Strides (2x/week): 6-8 x 100m at mile race pace after easy runs.
- Plyometrics (1x/week): Box jumps, bounds, single-leg hops.
You’re not training to be Usain Bolt. You’re training so your fast-twitch fibers are ready when your slow-twitch check out. That’s the difference between falling apart and PRing.
