An exercise apparatus comprising: a frame; first and second vertical guides coupled to the frame; first and second carriages carried on the respective first and second vertical guides, each of the first and second carriages having an upper carriage portion, a lower carriage portion and a carriage locking mechanism operable to lock and release the lower carriage portion to a selected vertical position along the first and second vertical guides; and an exercise bar coupled to the upper carriage portion of the first and second carriages, the exercise bar operable to translate or rotate to actuate the carriage locking mechanism.