i have heard opinions going both ways, what is the truth then? should run on sand ?
I heard it can make you slower.
The mechanics of running on sand are much different than running on hard surfaces.
We used to do LONG distance runs in Dive School on soft sand (6+ miles) and one of my instructors once told me to "run like an Elf".
This meant I kept my hands open and relaxed and I thought about barely touching the sand with my feet. Doing this, I can usually outrun/distance people that are used to running on pavement.
So, the big question is really about your goals. What are you training for?
make sure you have good running form before you try runnign a long distance on sand