For my whole life my bum has been cold. Like really really cold. I have joked with my family that I have "poor circulation in my ass" and I will make my husband fell what an ice cube I am carrying around in my pants to confirm I'm not crazy. This has been as long as I remember. I've even told my doctors about it - I mean it's really really cold!

Now with all the reading here and elsewhere after my AF, I find that the constricted IS reduced blood flow and causes the AF to form. Wonder if it's just a coincidence or if there is a connection.

I think normally the internal sphincter becomes hypertonic after a fissure is formed - thus preventing healing by constructing blood flow. Some people may be more prone to fissures though if they have a tighter than average sphincter to begin with - easier to tear during a large bm. Whether that's due to anatomical features or circulation I couldn't say.

When you say your butt is cold - do you mean your glutes/butt cheeks? I would check out foam rolling, it's like self massage. I'm a weightlifter and have really tight hamstrings and glutes. In order to loosen them up and wake them up so they would work properly, I used a trigger point foam roller and also rolled on a lacrosse ball and it certainly helps with both tightness of those larger muscles and circulation.

I do mean my muscles. But it's the whole bum.

My first AF was over 2 decades ago. At this point I can't recall if I had the cold bum before or only after.

Ok!

Well our bodies generate heat when we use our muscles (muscles use up energy, burning the energy in that area causes heat to be released, to put it simply). You could also think of it as a person with tons of muscle mass will burn more energy (calories) and produce more heat on a daily basis than one with little muscle mass. If you're very tight in that area or don't have good muscle development in the glutes or hamstrings, you may have poor circulation there. I bet the foam rolling along with some glute focused exercises (like old school Pilates clamshells!) would make a world of difference.

This is pretty interesting to me as I'm a personal trainer and physio student haha...and good glute activation and circulation is important fissure or no fissure - I would say it's the most common cause of low back pain, at least from what I've seen.

Sorry if that's too much info, I do enjoy being a nerd about this stuff!