Ask the 8a Coach #9: How to get better lock-off power?

How to train my biceps in a fun way to get as good lock-off power as the boys? Just doing pull-ups is dead boring! Yuji Hirayama once told me that one of his best training exercises was simply to lock-off and count to five on every move also on easier Routes or Boulders. You can actually make it a game with your friends when Bouldering indoors. However, do not overdo it the first few times in order not to get an elbow injury.