Last saturday, I went on a hike to summit a 10,000ft mountain. Started out at about 7800 ft, but descended to about 6500ft. All in all is was about 8 hours of hiking over very rugged terrain with thin oxygen. That was last saturday and it's now Thursday and my calves are STILL so sore that it's hard to walk up stairs. The other muscles in my legs were sore as well, but those recovered within 2 days. But I really must have ravaged my calves on that mountain adventure. I know it was one of the most physically exhausting things I've ever done.