Recently, I asked followers on Threads whether they had a preferred heel-to-toe drop. Some did. Others were less picky. Others still … well, they didn’t have a clue what I was talking about. Running shoes are seemingly becoming more complex each year. Not only do consumers have to consider the innumerable, often confusingly similar named foams, they also need to weigh up the importance, necessity, and impact of carbon or nylon plates that promise to help you keep up your pace with less exertion. One aspect that’s often overlooked is heel-to-toe drop. Despite drops differing by a maximum of approximately 12 mms, it’s (perhaps surprisingly) sufficient to alter one’s foot strike the impact on various joints. I’m by no means an expert in this field, but hopefully this guide provides a basic explanation of heel-to-toe drop to help inform future purchasing decisions.

What is Heel-to-Toe Drop?

The good thing is, heel-to-toe drop is quite simple to understand. Essentially, it’s the height difference between the heel and the forefoot thickness of the sole. So, if the stack height of your heel is 30 mm and the stack height at the forefoot is 22 mm, that’s a heel-to-toe drop of 8 mms. Simple, really. While minuscule height differences seem unlikely to alter your running strike or the load on joints, research seems to say it does. More on that later.

Do Brands Standardise their Heel to Toe Drop?

Running shoe companies don’t always manufacture their shoes with the same heel-to-toe drop. Some, however, do lean toward higher or lower (and even zero) drops. Others, such as Hoka, seem to favour 5 mm across the board (though I’ve not been through every single one of their shoes, so don’t quote me on this!) The intended purpose of the shoe (speed, daily mileage, stability, road, and trail) plays a key role in the decision behind heel-to-toe drop, though I’m sure there are other reasons for companies staying within a certain range (perhaps related to manufacturing costs).

When I initially discussed this topic on Threads and discovered that a good number of people were unaware of heel-to-toe drop, I knew it would be a good idea to provide a brief overview to hopefully clarify where different companies stand. It’s important to consider a shoe’s drop to ensure a shoe is ideal for your body. As I’ll touch on briefly toward the end of this article, these subtle differences may either help or exacerbate existing knee or ankle issues.

While it’s important we as runners do the work in strengthening the muscles around these joints (and I’m by no means suggesting a change in drop is going to miraculously cure an existing problem), heel-to-toe drop is definitely something you should consider.

The below list of running shoes is by no means exhaustive, but I’ve included some popular brands which cover an array of contrasting heel-to-toe drops.

Brooks

The Brooks Glycerin 21 utilises a reasonably large 10 mm heel-to-toe drop, with 28 mm in the heel and 18 mm in the forefoot.

Another popular shoe from Brooks, the Brooks Ghost 15, has an even higher drop, at 12 mm. 35 mm in the heel and 23 in the toe.

In the middle of the pack, Brooks’ max cushion trainer, the Brooks Ghost Max, utilises a 6 mm drop and is an extremely popular long run and recovery shoe. As with most Brooks shoes, they’re workhorses built to go the distance.

Hoka

In contrast to the norm of Brooks’ high drop, Hoka tend toward lower drop shoes. Hoka’s flagship road running shoe, the Hoka Clifton 9, the model’s ninth iteration, sports a 5 mm drop.

Even the company’s popular race shoe, the Hoka Rocket X 2, sticks to the 5 mm drop standard.

Altra

No article about heel-to-toe drop would be complete without including Altra’s lineup, a company dedicated to zero drop shoes. Despite being zero drop, Altra’s shoes are traditionally well cushioned – unlike the minimalist (or shoes (or barefoot) some runners opt for.

The Altra Via Olympus, with a midsole consisting of 33mm of Altra EGO MAX, is one example of their zero drop shoes.

In addition, Altra offer super shoes for those who prefer zero drops for races, notably in the form of the Altra Vanish Carbon 2, a shoe consisting of a stack height of 36mm of EGO PRO midsole foam and a full length carbon fibre plate.

You can also purchase the first iteration of the Altra Vanish Carbon at a considerable discount.

Why Do We Need to Consider Heel to Toe Drop?

Heel to toe drop is an important consideration. Yet, as with much running research, there’s a lack of it! Nonetheless, there are a few interesting studies I did find that demonstrate interesting findings.

Heel-to-toe drop is a prominent factor influencing lower extremity kinematics during running. Kinematics is the study of the motion of mechanical points, bodies and systems without consideration of their associated physical properties and the forces acting on them (thanks, Wikipedia).

In research by Zhang et al. (2021), eighteen habitual heel strikers performed trials wearing running shoes with four drop conditions: 15 mm, 10 mm, 5 mm, and zero drop. Results demonstrated “a greater foot inclination angle at initial contact and a lower vertical loading rate during the standing phase … when running in shoes with large drops compared with running in shoes without a drop.”

Additionally, “running in shoes with large drops, as opposed to without, significantly increased the peak knee extension moment, but decreased the peak ankle eversion moment.”

In simpler terms, the results of Zhang et al. (2021) suggest that shoes with higher drops (such as the Brooks Ghosts or Glycerin above), may have adverse effects for those with knee weaknesses, but may, conversely, be beneficial for those with ankle weaknesses.

Similar findings were observed by Richert et al. (2019), who compared a further four drop conditions: 4 mm, 8 mm, 12mm, and barefoot. As the authors note, “the results primarily showed that a 4 mm heel-to-toe drop led to increased vertical loading rate and maximum ankle moment and a decreased maximum knee moment compared to 8 mm and 12 mm.” In other words, the 4 mm drop shoe would be a better contender for those suffering knee weaknesses, confirming the conclusions of Zhang et al. (2021).

Conclusion

As noted above, there’s a great deal of strengthening that runners can and should be doing to address knee or ankle weaknesses (as well as muscular imbalances). If you’re anything like me, you’re likely not keen on lifting or on performing these additional exercises. I mean, we just want to run. Right? To help get you started, I’ll leave a link here from RebuiltPT. There’s a few really basic lifts and exercises that Nick recommends, and I think it’s a great place to start.

While strengthening the body is likely going to lead to longer term benefits, I nonetheless recommend considering the heel-to-toe drop of your shoes if it’s something you’re not already conscious of. If you’re currently running in high drop shoes and struggle with knee issues, why not try a reduced drop shoe? Similarly, if your issues are centred around the ankles, opt for a higher drop shoe and see whether that helps.