Running after brachytherapy

I'm a runner and wanted to get back to running regularly after my LDBT. My online search did not turn up any clear guidance on how long to wait, so I thought I'd post something that might help others in a similar position in the future. There was a thread in this forum from 2011 from a member who had a RP, but not a brachy patient that I could find. The most authoritative thing I found was from the Mayo Clinic and says:

You can resume normal activities when you feel up to it. Avoid strenuous activity, such as running, or activities that may irritate the perineum, such as riding a bike, until the area where the radiation was inserted is no longer tender.

Since I was feeling up to it last week (27 days after the procedure) I went running, actually a short, slow jog on a dirt path. I went a second time today. I had no problems with urinary incontinence or the prostate/perineum in general. I did have 3 problems on both occasions: 1 - the cold (to be expected in December); 2 - I'm out of shape; 3 - needed to take a BM. The second problem was no doubt due in large part to the sedentary nature of the last four weeks and was exacerbated by the fact that I had not run for a month before that due to an Achilles tear. I'm sure that will get better once I run some more. The third problem (frequent BMs) has been an unexpected SE of the brachy ever since the procedure. Of course I took care of all my toilet needs before going running, but even so, within about 5 or 6 minutes of starting out, I had an urgent need again. I run at a park. I barely got back to the parking lot rest room in time the first time. The second time it was about 8 or 9 min. in and I was near a rest room. I don't want to start a thread on this SE, so I'll leave it at that, but I wanted to warn any runners that they may want to run around the block or otherwise stay close to a toilet when you first resume running until you know the running isn't going to cause this problem.

My brachy was Cesium-131, so the radiation should be down to 13% strength or so by now. If you had another isotope, you may have SE's longer, so your experience may differ. There's been no problem with the physical trauma of the procedure, e.g. bleeding or pain, at least in my case.

I did start regular walks and light yard work (raking, etc.) after a couple of weeks and visited the gym twice a week for stretching and light upper body work, too, but that doesn't build up the aerobics enough for running fitness.

I played a round of golf the next day with no problem.

I continue to run (2-1/2 mos. after the brachy). The urgency for a BM is usually not there now, although it still happens sometimes. I can tell the rectum has still not fully recovered because my farts are still loud, meaning there is excess mucus there. A new side effect has started - a pain the shaft of my penis. It's a sharp pain in the sense that it comes on very suddenly like a pinprick, but it is not at all severe, maybe a 2 on a scale of 10. It happens once or twice a minute while running. It also happens sometimes just walking around the house, too. It never happens when I'm sitting down or standing still. It's located on the left side just below the head. I haven't heard of this before. I see the uro in a couple of weeks, I'll ask about it. I am now off Flomax. So far so good.