Attached is a video of a very common fault I see many athletes do on Bar MU. I call it an overreach in the arch position. This overreach causes an off tension/on tension event has a trickle down effect on the rest of the connectivity as the athlete kips from the arch to hollow position. I see this often on the first rep on Bar MU as athletes feel they must "reach" for more distance, in-turn, yielding more power. It actually does just the opposite. Many people will say that the first Bar MU in a set is the hardest because they can maintain theirconnection as gravity pulls them into succesive reps, but as fatigue sets in this habit will resurface!
Movement Spotlight: Bar MU/overarch from Power And Grace Performance on Vimeo.