Nazggul

Yes, your muscles need oxygen when you are working out. That's just one more reason to not hold your breath.

As always you need to consider what your goals are. Personally I don't lift in order to build bulk, I work on muscular endurance (lower weight, very high reps). However, the one constant no matter what you are doing is that you exhale while exerting and inhale on recovery.

Even in the power lifting example stated above you will note that these guys are always letting out a loud yell especially on big lifts. Well, that in fact is exhaling on exertion. Harry is right on the mark with his comments.

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