My Sore Bum

I ran today. Not particularly far, but a bit quicker than I have been. It was a good run. I tried pushing myself and it felt good. My heart rate averaged around 146, but by the time I was nearing the end of my run, it was up around 166. But it's not my legs, or my heart for that matter, that is sore. It's not my arms or my core muscles.
It's not even my back; not the muscles that work at holding me upright. They're called "erectors" for a reason. But my back feels fine.
Nope.
It's my butt.
Isn't it strange how that works?
...My butt muscles hurt!
I mean, I know why that is. I went to massage therapy college  for 2200 very,  long hours. If I didn't know how muscles worked together and all that I wouldn't have, or at least shouldn't have, graduated. But, it's still funny to me to see my schooling be related to my real life.
Muscles work in sets, or at least that is the easiest way to explain it without going into a whole bunch of anatomical jibber jabber. They work to counter balance each other, to support whatever muscle needs supporting. Actually, the human body is an interesting and wonderful thing, but it doesn't change that my butt hurts.
I know it's probably that there are certain muscle groups that need stretching; more specifically my glutes. Realistically, my hamstrings could probably use a good stretching as well. Hamstrings are a huge muscle group and actually attach right to the bones that you sit on. In massage college those bones were nicknamed your "sit" bones, but in reality they're called your "ishiel tuberocities.""
You make sure you remember that, K?  ? Especially since I spelled it wrong.
 If my  hamstrings are working hard and pulling on my "sit" bones with every step, then it's no wonder my butt is sore. I guess I was just taken aback when I started walking around today after my run, only to discover that it was my bum that was giving me grief and not other areas.
When I was training for swimming, I had some pretty sore muscles; upper traps, Lats, Pecs. Most of which were shoulder/back related. I got that, but not once did my butt hurt or an area that I hadn't directly worked. This is all new to me, but I guess I am training in a way I haven't before. I'm sure there will be some other surprises down the road. It's just really inconvenient when your butt hurts! Do you know how much you use those muscles to do every day tasks?!