Had the opportunity to film a few videos showing different techniques for improving your power endurance, with support from Metolius. The first one is based around the use of a campus board, except with your feet on the board at the back. The other three all use finger boards, which is great is you have limited space (one with feet on and the other two without).
The first two are shown below. By using your feet to reduce the weight on your arms, allows you to hang on for much longer, generating a much bigger burn. I get the best results from the one based around a campus board.
The remaining two ,shown below, have all your body weight on your arms. As a result the load is greater on your arms and fingers, leading to improvements in your finger strength. The small amount of time between the sets, ultimately leads to improvements in your power endurance as well, but not to the extent of the feet on work.