More Cushion, More Problems? New Research: Running Shoe Stack Height, Running Form & Injury Risk | Find Your Stride | Edinburgh Podiatrist

The modern running shoe looks a little like a moon boot these days — thick foam slabs, springy carbon plates, and marketing promises of effortless speed. But does more cushion always mean better performance and fewer injuries?

A new study from researchers at the Karlsruhe Institute of Technology (Kettner et al., 2025) suggests the opposite might be true: those towering “super shoes” could be changing the way you run — and not necessarily for the better.

The modern running shoe looks a little like a moon boot these days.

👟 The Study in a Nutshell

The researchers tested 17 experienced male runners wearing three pairs of shoes that differed mainly in stack height — that’s the thickness of the sole from footbed to ground:

• Low: 27 mm

• Medium: 35 mm

• High: 50 mm

Using a 3D motion capture system, they analysed how each shoe affected running mechanics and stability at two speeds (10 km/h and 15 km/h).

📊 What They Found

1. High-stack shoes change your running style

Runners in the 50 mm shoes showed longer ground contact times and lower step frequency, suggesting a more “sticking” stride. They also bounced more — greater vertical movement of the centre of mass, which usually means less efficient running.

➡️ Translation: You may feel bouncy in those thick midsoles, but your body is actually working harder to control the motion.

2. Stability takes a hit at 50 mm

The highest-stack shoes caused runners to spend longer in an everted foot position and showed less control at the hip. Both changes point to reduced stability and raise concern of greater injury risk, particularly around the ankle and pelvis. Interestingly, the mid-height (35 mm) shoes performed best for overall balance and control.

➡️ Translation: Somewhere around 30–35 mm might be the “sweet spot” — cushioned, but not so high that you lose feel and control.

3. Speed didn’t really matter

These biomechanical effects were seen at both speeds. So whether you’re out for an easy run or chasing a PB, your shoe’s stack height will likely influence how stable you feel and how efficiently you move.

⚕️ Why This Matters for Runners and Clinicians

For podiatrists, physiotherapists, and coaches, this research adds to growing evidence that too much shoe can be a bad thing — particularly for runners who already struggle with stability, balance, or previous lower-limb injuries.

• Longer eversion time and reduced hip stability are linked to overuse injuries like shin splints, Achilles tendinopathy, and ITB pain.

• The increased vertical bounce seen in high-stack shoes may also impact running economy, meaning you’re burning more energy to achieve the same pace.

• From a regulatory point of view, the study supports World Athletics’ 40 mm limit — the 50 mm shoe tested here exceeded that and clearly compromised control.

🔍 A Few Caveats

Like all good research, this one had limits:

• It only included 17 male runners, so results might differ for women or beginners.

• The highest shoes also had carbon rods, which may have influenced the results.

• All running was done on a treadmill, not outdoors on variable terrain.

• The study didn’t directly test running economy or injury outcomes, just the biomechanical patterns that often precede them.

Still, it’s one of the most comprehensive looks yet at how stack height alone can alter both running mechanics and stability.

🦶 The Takeaway for Your Feet

• More cushion ≠ more protection. Beyond a certain point, extra foam can dull proprioception and delay your body’s natural reactions.

• Balance is best. Shoes around 30–35 mm seem to offer a good compromise between shock absorption and stability.

• Match the shoe to the runner. Those with a history of ankle instability, hip control issues, or overuse injuries may fare better in moderately stacked or traditional shoes.

So before you reach for the tallest “super shoe” on the wall, remember: the best shoe isn’t always the one that makes you taller — it’s the one that allows you to move naturally and stay injury-free.

Find Your Stride!

Citation:

Kettner, C., Stetter, B., & Stein, T. (2025). The effects of running shoe stack height on running style and stability during level running at different running speeds. Frontiers in Bioengineering and Biotechnology, 13, 1526752. https://doi.org/10.3389/fbioe.2025.1526752