I'm at Wk3R6 so 25 mins running and my calves are really starting to get tight. I'm surprised I've not had problems before this week, even with the 20 mins run in W5 (but that was on a treadmill and the runs now are on hilly terrain). I stretch well when I get in for 10mins or so and then have a nice warm shower or bath. I feel like I'm going to have to have two days off when I normally only have one. Any ideas to help the problem?