The meaning of the phrase tearing himself loose as it is used in the passage is this: the men were so excited or enthusiastic that they could not contain themselves.
What is the meaning of the phrase?
The phrase "tearing himself loose" suggests forceful breaking free, implying an intense surge of emotion pushing against some kind of restraint. The description of the men being "excited or enthusiastic" also aligns with the image of needing to break free from something holding them back.
So, "tearing himself loose" involves physically breaking free from a restricting situation, like escaping a crowd or breaking through an obstacle. It implies emotional liberation, breaking free from negative feelings or limitations.