How to do it:
Shorten the straps on your TRX so that, when you sit beneath the handles, you can just about reach them.
Holding the handles and with your legs out straight in front of you, bend your arms and pull yourself up. Allow your wrists to rotate naturally.
Extend your arms and repeat.
Supercharge this exercise by keeping your legs locked in place and lifting them off the floor. This is called an L-pull-up.