2 Gym Mistakes Runners Make That Can Ruin Your Marathon Training

Estimated read time: 3 minutes

Hey! - Performance Nerd Jonah here.

You probably think that lifting weights will automatically make you a faster marathoner.

It’s not that simple.

Most runners I see are doing gym work that hurts their marathon training more than helping it!

Let’s dive into 2 major mistakes runners make in the gym and what you can do instead.

Enjoy this week’s guide, the nerdy question, and my favorite sciencey finds.

Mistake 1: Lifting Light Weights 🏋🏽‍♀️

Your favorite running influencer has told you to lift light weights for 20-30 reps. But lifting light weights for high reps is a terrible idea for runners.

Data shows that gym exercises that improve your lower body strength and power lead to the best gains in running performance.

You don’t get strong and powerful from light weights for 20-30 reps.

You get strong by lifting heavy weights for low reps and you get powerful by lifting moderate weights as fast as possible!

Sets and Reps for Strength and Power:

• Strength: 3-8 reps with a weight that is 8/10 effort (80% Max)

• Power: 2-5 reps at 6 /10 effort moving the weight fast

Mistake 2: Lifting to Muscle Failure

Sept 20th, 2014. The day I almost died.

Picture this: I was in my hometown gym trying to set a new bench press record. I just completed 4 reps with 225 pounds on the bar (humble brag cause I’m the strongest runner you know).

Then came my moment of reckoning.

As an overconfident 18 year old nerd, I went for a 5th rep. Spoiler alert: it was an awful idea.

I lowered the bar. I pushed with everything I had. No budge. My muscles were exhausted.

Live look at 18 year old me thinking I’m killing it in the gym:

This is called lifting to “muscle failure” or to the point where you can’t complete any more reps because your muscles are too tired.

Lifting to “failure” puts a lot of tension on our muscles, telling them to come back larger. So, like we talked about, doing 5-20 reps and getting close to failure is a great way to build bigger biceps. 💪

Big biceps are cool, but they won’t win you any marathons. (Until I prove science wrong 😉).

But lifting to failure causes muscle damage and soreness that lasts several days. This soreness can ruin the quality of your running.

Science has proven that lifting to failure doesn’t improve gains in strength and power.

So, lifting to failure doesn’t cause adaptations that improve running but can lead to extra muscle damage you want to avoid. 🤔

Sounds like a worse idea than when my dog, Augie, decided to chase a skunk. All the air fresheners in the world can’t fix the smell in my 400 square foot apartment.

Instead you should stop all your sets when you could still complete 3-5 more reps safely.

I’ll spare you the details of how that story ended. But I don’t think I’ll be invited to that gym’s annual holiday party any time soon.

Practical Summary

• Focus on muscle strength and power

• Stick to 3-4 sets of 3-8 reps in the gym per exercise

  • Heavy weights (8/10 effort) for strength

  • Moderate weights (6/10) lifted as fast as possible for power

• Stay away from muscle failure

  • Stop sets when you can still perform 3-5 more reps safely

• Some muscle soreness will occur any time you start a new lifting program and that’s okay!

Don’t forget: You + Science = AWESOMENESS 😎

Yours in science,

Jonah

Please email me directly if you’re interested in references for this week!