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If you need a little extra motivation to get out the door in the morning, a cup of coffee helps—especially one made for runners. ☕️🏃‍♂️We’re excited to partner with Long Run Coffee for this issue of The Hammer—check them out below!

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For those of you curious about sport science, you’re in for a good read! Today’s newsletter is brought to you by performance coach Jonah Rosner, who breaks down the science of a unique running metric called Leg Spring Stiffness.

But that’s not all, Jonah is also offering a FREE Foot & Calf Gym Plan to help boost your performance!

👉 Download it here: Foot & Calf Gym Plan

About Jonah:

• Former NFL sports scientist with experience across all major U.S. pro sports.

• Partnered with Nike to launch the Nike Running Performance Lab in NYC, using tools from NFL athletes.

• Runs the Marathon Science newsletter and a marathon training program integrating tech, AI, and performance testing.

The Secret Running Metric That Could Slash 10 Minutes Off Your Marathon

Hey - Jonah here. 💪

Want to run faster with less effort? Here's the secret.

Ever noticed how elite runners seem to glide effortlessly while others struggle with every step? The difference might be a little-known performance metric: Leg Spring Stiffness.

Research shows that optimizing running stiffness can boost your efficiency by up to 8%. 

For a 3-hour marathoner, that’s over 10 minutes shaved off your time—without running an extra mile.

Let’s dive into what Leg Spring Stiffness is, why it matters, and how you can harness it to transform your performance.

The Secret Spring in Your Step

Imagine two rubber bands: one stiff, snapping back instantly when stretched, and one loose and floppy, slowly returning energy.

Your Achilles tendon works in much the same way. A stiff Achilles quickly bounces back with every step, efficiently handling impact forces. 

This rapid response means your muscles don't have to work as hard, conserving energy and improving your running economy.

Here's something wild: A recent study found that improving leg stiffness boosted running economy by 4%—the same improvement you get from those $250 super shoes!

 Except this upgrade works in every shoe you own.

Two Types of "Stiffness" That Matter

1. Vertical Stiffness: The Bounce Factor

Elite runners glide with minimal up-and-down movement. This is called vertical stiffness. The less you bounce, the more energy you conserve for forward motion.

2. Leg Stiffness: The Spring Effect

Think of your legs as racing springs. Better springs mean faster running with less energy. Optimizing leg stiffness is like upgrading from old bedsprings to high-tech racing shocks.

Here are some of my favorite watch metrics to assess your spring quality:

1. Vertical Oscillation

   • Measures wasted vertical motion

   • Lower numbers = more efficient running

   • Elite runners consistently minimize bounce

2. Ground Contact Time

   • Tracks how long your foot stays on the ground

   • Lower ground contact time over time might show improvements in your natural spring (stiffness)

Level Up Your Leg Springs 💪

Running alone won't optimize your springs. You need two proven methods to improve leg stiffness: heavy strength training and plyometrics.

Heavy Lifting: Building Premium Springs

Tendons respond best to heavy, controlled work. Follow this science-backed protocol:

1. The Isometric 4% Protocol:

   • 4 sets of 4-second heavy isometric heel raise holds 

   • Keep heels elevated throughout the set

   • Research shows this improves running economy by 4% (hello super shoes)

2. Power Builder:

   • 3–4 sets of heavy calf raises

   • Lower for 3–4 seconds

   • Increase weight weekly for gradual progression

Plyometric Power: Teaching Springs to Bounce

Plyometric exercises bridge the gap between strength and running explosiveness.

1. Quick Power Work:

   • 3–4 sets of 5 max-effort jumps

   • Full recovery between sets for quality

2. Spring Drills:

   • Quick pogo hops focusing on minimal ground time

   • Start with 2 sets of 10 seconds, increasing gradually

Your Fast-Track to Better Springs

✓ Measure your baseline metrics

 ✓ Add 2 heavy lifting & plyo sessions weekly (30–40 minutes each) 

✓ Track weekly changes in stiffness metrics and running economy

 ✓ Build gradually over 8–12 weeks to avoid overload

Want to Start Seeing Results in the Next 8 Weeks?

Here's the truth: every day you run without optimal leg springs is a day of wasted training potential. Elite runners know this secret—now it's your turn.

My 8-week Calf and Foot Training Plan has helped hundreds of runners slash their PRs. Last month alone, three athletes knocked 8+ minutes off their marathon times.

Download your free plan now and unlock:

• 📅 8 Weeks of Training: Two full foot and calf gym sessions, repeated over 8 weeks to build strength and endurance

• 📹 Instructional Videos: Easy-to-follow YouTube videos for each exercise, so you can see exactly how to perform them

• 🏠 Flexible Options: Tailored exercises for both the gym and those working out at home—no gym equipment? No problem!

• 📈 Targeted Details: Precise sets, reps, and weight recommendations specifically designed for distance runners

• 💪 Clear Instructions: Step-by-step guidance for every exercise ensures you perform them correctly and maximize your results

Don't leave minutes on the table in your next race. Don’t wait! Grab your free plan now and start seeing results in just 8 weeks!

👉 Download it here: Foot & Calf Gym Plan

P.S. The sooner you start, the sooner you'll see results. Download your plan now and join hundreds of runners who've already transformed their running economy!

Don’t Forget - Free Travel Set for The Hammer Subscribers!

Switch to Long Run Coffee and feel the difference in your training. Your legs will thank you.

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