The truth is that the jury’s still out on whether running on a softer surface has less impact on joints and muscles. Some research suggests it might not actually matter, and the forces that impact your lower body on various surfaces such as asphalt, concrete, and grass don’t increase knee pain or injury risk. One explanation is that your body automatically adapts to the surface you’re running on. That means you’ll instinctively strike harder on softer surfaces, and strike softer on harder surfaces. On the other hand, some evidence suggests that running on softer surfaces (such as grass) reduces stress on your muscles and joints.
“But it feels better when I run on soft surfaces,” you might say. That difference in feeling is likely due to the different kinds of muscles, or stabilizers, you use when running on softer surfaces, which creates a sensation of less impact, although the overall impact on your body is the same.
That’s not to say that you shouldn’t run on soft surfaces if it makes you feel better. Feeling better on a run goes a long way. However, softer surfaces such as trails, grass, or sand tend to be more uneven, which can pose a greater risk of strains and sprains.
When it comes to injury prevention and recovery, it’s also important to consider other factors such as wearing the right running shoes. And be sure to increase your running intensity and volume gradually to help avoid injury too.