The most common cause of rucking failure? Feet problems. Now, I’m not primarily referring to 1-2 hour rucks, even though these apply. What we’re looking at are 4+ hour rucks.
It’s important to toughen your feet without creating callouses. How do you do that? A lot of rucking and walking barefoot (take your shoes off at home), and there is the option of chemical tougheners.
But really, at the end of the day the best way to toughen your feet is a lot of rucking in the same pair of shoes or boots. Your feet have to get past the bruising, tenderness and strain of being under constant weight; and they will.
A combination of 3 things create blisters: heat, friction and moisture. Remove one of those and you won’t get a blister.
The first step is good fitting shoes/boots that breathe and drain water easily. For this reason, don’t get anything Gore-Tex. Make sure you have ample room in your toebox, and that your heel never even hints at slipping. The author of Fixing Your Feet recommends an extra 1/2” of room in your toe-box, allowing swelling-room and eliminating toenail friction.
Keep your toenails trimmed. It should go without saying, but overly long or ingrown toenails create problems. Period.
Next step is killing friction. Using the right product will eliminate friction and keep you from blistering, even when your feet are soaking wet and hot. Trail Toes is my preferred poison and worked great for me, Jonathan and Zac through our first Goruck Challenge. Some folks like Bag Balm or just plain old Vaseline.
Bottom line: spend time under your ruck and use the same equipment you plan to use for your endurance event.