taking peak flow reading

Ok i'm sure I really should know better by now, but when doing your peak flow, should you be blowing out with just your lungs, or should you use your stomach muscles too? My pb is 550 bit I'm only getting 350 at the moment even though I feel fairly ok so I'm not sure if I'm doing it right! Can't really ask nurse now, she'll think I'm daft! LOL

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Probably not the one to ask as I am terrible at PF technique, but since you're supposed to breathe from the diaphragm I kind of assume you're meant to do PF from there as well?

Just tried it, readings all over the place as usual but I was using my stomach muscles/diaphragm...

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I have always been told that its a short sharp breath, i have been trying since i read your post and i cannot do it without using my stomach muscles so i guess either you do use your stomach as well or i have been doing it wrong for 8 years!