After doing three 5k all grass runs including the race for life last week , my legs feel heavy & stiff , I haven't felt like this since the early days in October . I was supposed to be doing park run tomorrow , but I'm thinking maybe I'm going to give it a miss . Did 5k on weds. No problems but don't want to risk injury . What do you lot think ? Is it coz I'm not used to grass running ( what I won't be doing again ) I hasten to add ? They feel as stiff as boards ! Any advice gratefully accepted .