Warriors need serious grip strength. For many obstacles, it's what is supporting your entire bodyweight. That's one big reason why rock climbers like Caldiero have crushed the course. Head to a rock climbing gym and do the following on a hang board, or what Caldiero calls "a pull-up bar on steroids."
Do the first 10 percent of a pull-up (so you're pulling up only a couple inches) and hold as long as you can. This will engage your muscles without relying on your skeleton for support. Drop down when you're tired; rest one minute. Repeat once in each hand position. Start with at least three increasingly difficult hangs for six total sets.
The idea is to work varying grips. This will give you contact strength, or the ability to grab onto a bar, ring, ledge, or handle in an obstacle with 100 percent force so you don't drop, says Caldiero. Start by using bigger grips — like holding on with your full hand — then gradually progress to smaller grips, like a two finger hold or hanging by the tips of your fingers only.
Can't get to a rock wall? Use the pull-up bar at your gym, working from a full-palm grip to finger tips.