Although some evidence suggests that running on softer surfaces reduces stress on your body, but there isn’t a conclusive body of research to support that running on a softer surface is better for your joints and muscles.
Body - Physical Training_d
Although some evidence suggests that running on softer surfaces (such as grass) reduces stress on your muscles and joints, there isn't really a conclusive body of research to support that running on a softer surface is any better for your joints and muscles. Your risk for knee and injury pain might not be related to whether you choose to run on grass or concrete at all. One explanation is that your body automatically adapts to the surface you're running on. So without realizing it, when you're running on softer surfaces, you probably have a harder foot strike, and when you run on harder surfaces such as asphalt and concrete, you instinctively strike a bit softer.
How you feel when you run on different surfaces is just as important. If your body tells you it feels better when you run on softer surfaces, then you should listen to it. This 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.
One thing to consider when you're running on softer surfaces such as trails, grass, or sand is that these surfaces 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 training practices. Gradually increasing the intensity and duration of your running can help you avoid injury too.