"My biggest training tool is the pull-up," says Joe Moravsky, Ninja Warrior pro and TV personality. It helps with every single obstacle that uses your upper body, he says, notably the salmon ladder, doorknob arch, and the invisible ladder, which require serious strength in your biceps, triceps, and lats. To work those pull muscles from a variety of angles, try his combination of pull-ups and pull-downs.
First, do a maximum number of pull-ups.
Next, do 10 Pull-downs: Stand on a bench, and get into the top of a pull-up position, head and neck above the bar. Slowly lower down until you're hanging with arms straight; repeat.
Don't rest between moves. When you master the the pull-down, try it with one arm.