How Does Shoe Drop Affect Running? 8mm vs 4mm vs Zero Drop

Are you overwhelmed by the amount of information there is about what makes a good running shoe? Maybe you have seen or heard about the now somewhat infamous toe shoes that look a bit like something out of a science fiction movie, or at least more like something you would only wear while snorkeling. Ever since toe shoes first appeared on the market, there have been many arguments both for and against minimalist shoes with very few conclusive results.

Shoe drop affects running by either encouraging or discouraging correct form and preventing potential injuries to certain areas of the body. The primary difference between shoes such as toe shoes and common running shoes is the amount of drop.

In this article, we will discuss the advantages and disadvantages of zero drop, low drop and high drop shoes, the affect each type has on running form, the potential injuries to watch for, tips for acclimating to low drop shoes and which type of running shoe might be right for you.

What is Heel Drop?

Heel drop is the difference in heel height from the sometimes thickly padded back part of a shoe to the less padded front.

A 2016 study published by the American Journal of Sports Medicine focused on three groups of runners for a total of six months. The shoes each group wore were the same except for the drop: 0, 6 or 10 millimeters. Surprisingly, the injury rate was the same regardless of which shoe type they wore—approximately 25 percent of each group had an injury during the study.

The most important aspect of running is your form—as long as you learn how to strike with your midfoot or the ball of your foot first instead of your heel and find a shoe that encourages you to do that, the drop is not the factor with the highest level of influence.

What is Pronation?

Pronation refers to the amount and direction that your foot rolls while exercising, and there are three types: basic, overpronation and supination. If you are prone to basic pronation, your foot rolls inward to a normal degree.

The brunt of the force goes to the ball of your foot and a bit of the heels, which makes neutral, stable shoes that are lightweight the best choice. Neutral shoes are running shoes with less rigid arch support, and stability shoes include devices that help control side-to-side movement.

If you tend toward overpronation, your foot usually rolls inward too much. This causes the inside edge of your foot to take the most impact. In this case, more structured, supportive shoes with a high drop or even motion control shoes are a better choice. Motion control shoes often have stiffer heels, denser foam and reinforcements for the arch area.

Supination means that your foot is prone to rolling outward to an excessive degree. If the outer edge of your foot is receiving the greatest impact, neutral shoes might be the right fit for you.

12 mm vs. 8 mm Heel Drop

Most running shoes have at least a slight heel drop, which can potentially change your gait and contribute to why running is one of the activities with the highest level of injuries.

Normal running shoes have a drop of 8–12 mm, tilting your foot; the heel is sometimes twice as high as the front of the shoe. A 12 mm drop used to be the standard, but the push toward more minimalist shoes has led to a drop of 8 mm being more common.

Cushioning under the heels does help absorb the impact to your legs, but it also could promote heel-striking. The other downside is that having a thick platform under your foot causes more ground contact and a longer impact time and increases the risk for injuries from overuse.

However, there are some benefits to having a shoe with heel drop.

If you tend to put your weight on your heels while running or train on hard paved surfaces such as asphalt, a high drop (more than 7 mm) is ideal. Also, if you have leg-length discrepancies, problems with your Achilles tendon or you frequently wear shoes that have a higher heel, a high drop shoe is most suitable.

If you are already prone to striking with the middle or front of your foot, a low heel drop (from 0 to 6 mm) is a good choice.

What is a Zero Drop Running Shoe?

Zero drop means that the ball of the foot and your heel in a shoe are the same height, like going barefoot. Zero drop shoes were originally created to help runners with injuries, but became very popular with people who wanted to run more naturally.

There is still a sharp divide between proponents of zero drop shoes and people who staunchly oppose them, and there are several notable advantages and disadvantages.

Advantages
  • They can potentially increase alignment between your feet and body.
  • They focus the shock on the intrinsic muscles of your foot and distribute force more evenly, easing the impact on your joints and increasing the protection from injuries to the knees and hips.
  • They can increase stability.
  • They are lighter and require less energy.
  • They can possibly strengthen your feet and increase flexibility, although there is still debate on this.
  • Especially for people with wide feet, zero drop shoes will allow your toes to spread out adequately.
Disadvantages
  • They might increase the risk of injuries for your feet and lower legs in the process of protecting your knees and hips.
  • They do not give you as much traction in icy or wet conditions.
  • They could increase the risk of tendonitis in your Achilles tendon, strained calf muscles and metatarsalgia or stress fractures.
  • They offer less protection against jagged rocks or debris such as glass on the road.

Benefits of Low Drop Running Shoes

Young woman running

There are many benefits to a minimal shoe that has a bit more drop than a zero drop shoe. For an example, something in the range of 4–6 mm. These shoes are lightweight with a low amount of arch support. A shoe in this range offers a bit more support and protection from injury, while still strengthening and increasing the flexibility of your foot by encouraging good running form.

However, minimal shoes do muffle sensory information to a certain extent, which paired with the lack of motion-control support, could potentially lead to injuries for some runners.

Some people also prefer to use different drops for different activities, such as zero or low drop shoes for short speed events and a higher, more commonly used drop for long distances. Switching between drops (as long as you make sure to adjust to each safely first) also can strengthen different parts of your feet and lower body, making you a stronger runner overall.

This is especially useful if you frequently run on very different surfaces because that will affect the muscle groups you implement in order to run the most effectively.

“This is why kids who grow up in third-world countries are often successful runners,” certified running coach Sean Coster told Active.com. “By running barefoot, they develop a low arch and a stable foot. This is always going to be an advantage. Getting a lower heel to forefoot can help with dorsiflexion and plantar flexion.”

Improving your dorsiflexion and plantar flexion makes your entire foot more flexible.

Chris McDougall’s 2009 book Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World Has Never Seen is also a convincing case for low or zero drop running. He researched the Tarahumara tribe in Copper Canyon, Mexico, and found that they frequently participate in races that are more than 100 miles, even into their old age, wearing homemade sandals.

Furthermore, they did not encounter the typical problems of runners, such as shin splints, tendonitis and stress fractures. This example proves that form is the most important component of running, even if your footwear does not meet the standards Western shoe companies promote.

Further evidence includes the running careers of athletes Abebe Bikila and Zola Budd, who won the 1960 Olympic Marathon in world-record time and the 1985 and 1986 IAAF World Cross Country Championships, respectively—both runners completing the events barefoot.

However, both of these examples also illustrate the benefits of switching between drops and styles to be more effective for different situations, as Budd wore shoes to train on hard surfaces such as pavement, and Bikila also changed shoes for a different world-record win. In conclusion, the form of these runners is what made them successful, regardless of the drop or shoe type.

Below is a table to use as a quick reference for the advantages and disadvantages of each primary category of drop.

Zero Drop Shoes Explained

  • Pros: Lightweight; can be more stable and requires less energy; can provide more room for toes to spread properly; can help with alignment
  • Cons: Less traction and protection; not suitable for people with overpronation or recurrent heel-striking
  • Designed to: Increase the natural strength and flexibility of your foot by distributing force more evenly.
  • Risk of Injury: Feet and lower legs, such as the calves and Achilles tendon
  • Running Form: Promotes the proper form of striking with the forefoot or midfoot

4-6mm Shoe Drop Explained

  • Pros: Lightweight, requires less energy; can help with alignment; offers protection against rough terrain and debris
  • Cons: Muffles sensory information to your feet
  • Designed to: Improve running form while still providing protection.
  • Risk of Injury: Feet and lower legs, such as the calves and Achilles tendon
  • Running Form: Feet and lower legs, such as the calves and Achilles tendon

8-12mm Shoe Drop Explained

  • Pros: Good for people who tend toward overpronation; offers more protection for the feet and lower legs
  • Cons: Could lead to poor alignment and running form.
  • Designed to: Provide structured support and offer cushioning to protect the heel from impact and rough terrain.
  • Risk of Injury: Knees and hips
  • Running Form: Can lead to heel-striking

Tips for Acclimating to Zero Drop Running Shoes

  • Tip #1: try wearing them for short periods during the day, increasing the distance and frequency slowly.
  • Tip #2: avoid steep inclines at first and make sure to stretch your calves and feet before and after you use zero drop shoes.
  • Tip #3: perhaps start with an intermediate minimalist shoe in the 4–6 mm range.
  • Tip #4: practice your form by trying to strike gently with your midfoot instead of your heel.
  • Tip #5: run with short strides—use a metronome app to help you make around 180 strides a minute.
  • Tip #6: do not increase your weekly distance by above 10 percent.
  • Tip #7: to improve flexibility and strength in your feet, try physical therapy exercises such as towel scrunches, calf raises and tennis-ball foot massages.
  • Tip #8: be patient as it might take at least four to six weeks to adjust to zero drop shoes, if not four to six months.

A Word from Love At First Fit

Because there is not quite enough scientific evidence or research regarding shoe drop to make a conclusive claim about which type is best, the answer has to be more subjective, as every person’s foot and way of running is slightly different.

If you find that your feet often tend toward overpronation, it is important to have the cushioning and protection that a high drop shoe offers, unless you work to correct that tendency. Additionally, if you are prone to injuries in your feet and calves or frequently run on asphalt or other hard surfaces, high drop shoes would most likely be better than low drop shoes.

However, if you are a seasoned runner who already has the proper running form of striking with your midfoot or forefoot, or you are working toward that, zero or low drop shoes can help you toward that goal as well as help reduce strain on your knees and hips.

At the end of the day, the most important part of running is focusing on your form and making any drastic change to the type of running shoe you wear very slowly.