When I was somewhat heavy, with a BMI of about 28, I could bring on AF when bending over to tie my shoes or when putting on socks, even. I attributed the response to tonal change in the Vagus nerve (you should research this issue), but I think that change was due to visceral fat encroaching on internal organs. Bending over to tie shoes does put a heckuva strain on one's innards if it is replete with visceral fat.