I just signed up for a mud run... I didn't even think about having to grip things with muddy hands... Oh man, I gotta lot of prep work to do...
Burpees mate. I've done a few and if you can manage 50+ burpees a day, it will help you so much, did with me anyway.
Hey, if you go onto spartan race website there are workouts of the day. Tough mudder and spartan race are very similar.