BTW I wish I could tell you guys what I do right, I never get cramps. I remember I had done the Zugerberg the day after my Inferno HM last year, as recovery run

What I do get is a dull ache and a feeling of leaden calves during the first 30-45 mins, but after that they work without complaint for several hours.

I do do a very thorough stretch once a week, not sure if that has a role.