>>76124116yes i do all my "easy" days so that about 60-70% of the session is on grass (and significant portion of a hard session in fact)
i still do get some niggles especially because i have some pretty big long runs on concrete
but if i try to do everything on concrete with my mileage, my body breaks down
grass is so much easier on the body and i need it to run big miles or else i have to take rest days or slow down some sessions too much