I had to turn around on a long (5000ft) glacier route last week because one of my ankles had really begun to hurt. The ankle was so fatigued after 1000ft that I doubted my ability to safely finish the remaining 4000ft, and the descent. I had decent double plastic boots, and had no problem kicking steps up soft snow the day before, but cramponing up a long, 25-35°, solidly frozen slope was apparently more than my ankles could handle.
Is there a training regimen for foot and ankle strength?