Does Running Surface Influence Injury Risk?

Nick Gornick, PT, DPT | October 22, 2023

When it comes to optimizing performance and preventing injuries in running, there are many factors to consider. One debate among runners revolves around the impact of running surface on injury rates. While many believe that pounding the pavement might lead to more injuries compared to running on grass, the truth isn’t as straightforward as you might think.

Let's take a closer look at the available data to determine whether your running surface really matters for your injury risk.

What We Know About Running Surface and Injury Rates

1. We Alter Our Leg Stiffness to Match the Running Surface:

Leg stiffness refers to how rigid or flexible the leg is upon landing during a run. For instance, on harder surfaces like concrete or asphalt, runners tend to land softer, i.e., decreased leg stiffness. This is the body’s way of decreasing the impact due to the harder surface. Conversely, on softer surfaces, leg stiffness increases because the surface absorbs more of the impact. These findings show that the impact on the leg remains relatively constant regardless of the running surface (Edwards 2009).

When moving between surfaces, the body adapts very quickly. A group of researchers measured the biomechanics of runners as they ran across different surfaces. What they found was that runners changed their leg stiffness to match the surface type after just one stride (Ferris 1999).

This same phenomenon happens when running in different shoe types. With the advent of maximal shoes, researchers have investigated how maximal cushion influences loading rates. When running in a maximal shoe, runners alter their stride and land up to 25% harder/stiffer compared to a neutral shoe (Pollard 2018). Much like running on a softer surface, runners naturally alter their loading rate in response to the cushioning in their shoes.

2. Studies show conflicting data on the topic

Two studies have found a correlation between injuries and running surface, but they were both retrospective studies. While one of these studies found that running on concrete surfaces correlated with a higher injury risk in women, it didn't show the same correlation in men (Marti 1988). The other study suggested a connection between running on hard surfaces and back and thigh injuries (Wen 1997). We currently don’t have any other information to help piece this puzzle together, as both of these results are incidental findings in studies that looked at many different factors.

3. Plantar Pressures on Hard Surfaces:

Plantar pressure refers to the amount of force exerted on the sole of the foot during running. Research indicates that plantar pressures are indeed higher on harder surfaces (Wenxing 2023, Tessutti 2023). This suggests that the force on the bottom of your foot is increased when you land on a hard surface. However, we don’t see this increase in stress higher up the leg in the knee or hip, likely due to our body adjusting leg stiffness as described above.

Missing Data:

We don’t have any randomized control trials on this topic. To really get a better picture on this topic, we need some more research. Specifically, we need to take 2 randomized groups of runners and have them run on soft vs. hard surfaces for a training block. From this data, we could better determine if running surface matters, because the groups are randomized at the start.

Key Takeaways:

• Running surface might not matter as much as we thought based on the current research.

• The human body is incredibly adaptable, and our ability to adjust leg stiffness indicates we are equipped to handle various terrains.

• There are a couple of studies that find a correlation with running surface and injuries. We need more prospective data to learn more. No large-scale, high-quality studies have looked closely at whether running surface significantly impacts injury rates.

• We need randomized control trials on this topic.

Runners might be better off worrying less about their running surface and focusing on other variables, such as sleep, nutrition, mileage, training intensity, and recovery. These factors have more substantial evidence supporting their impact on performance and injury prevention.