Is it safer/healthier to run on grass than concrete? I like to run laps on a soccer field near my apartment rather than on city sidewalks so I don't have to deal with traffic. But I seem to be the exception in my neighborhood. I see tons of people running down the streets, but nobody running on grass. I assumed that a softer running surface would create less impact on my joints and prevent injury and reduce wear and tear on my body. But I could be wrong. Just curious.
Completely depends on how you run. The trend I see is that everyone thinks running on hard surfaces incurs more impact, but that isn't necessarily the case.
Dredged that out of my memory from a couple years ago.
Heel strike - Effective mass is approximately the foot plus the lower leg, which equals 6.8% of total body mass.
Forefoot strike - Effective mass is the forefoot and some portion of the rearfoot and leg, which equals 1.7% of total body mass.
"We have found that even on hard surfaces (a steel force plate) runners who forefoot strike have impact forces that are 7 times lower than shod runners who heel strike. Rates of loading are equal to or less than rates of loading for shod runners."
Probably depends on how you run. If you're a forefoot striker, running on asphalt is probably better than running on grass, because the vast majority of the impact will be absorbed by the calf/foot muscles. The danger from stepping in a hole or tripping over an object hidden in the grass probably outweighs the minimal increase in impact from running on concrete (not that either of these should actually be a significant danger).
On the other hand, if you're a heel striker, the reduction in impact might be worth it. Stomping on concrete with your heels sends a lot of force through your ankles and knees.
