Hand movements while stuttering & asthma-related?

Hand movements while stuttering & asthma-related? My girlfriend stutters but recently I realized when she stutters on a word she shakes and flails her hands quite noticeably and tilts her head. Is this common among stutterers? Also, she tells me that when she is on oxygen, meaning when she puts on a mask to inhale her asthma medication she doesn’t stutter at all afterwards. Is this also common?