38 year old female age group triathlete. Decent-to-good runner, for a 38 year old age group triathlete. I spent all last year injured so I've spent the past 6 months clawing my way back, and I've been happy with my progress. For a while now I've been consistently running tempo miles at a 7:13/mile pace. So somewhat challenging for me, but totally doable for long stretches.

I also have glaucoma, and it currently is not as controlled as my doctor or I would like. As I wait for her to return from vacation to do a laser procedure, she put me on 500 mg of Diamox 2x a day. This started last Tuesday (9 days ago) and since then my runs have gone to shit. I did my first run last Thursday, and I could barely hold the 7:13 for 2 12 minute sets. I did it, but I felt like I was going to die and I had to take a walk break in between. Similar issues for my run on Saturday and my brick on Sunday; I did it, but it felt so, so, so hard. Today was even worse. I gave myself a long warm up, but couldn't make it through my 30 min set and had to drop my pace twice, then take a walk break. I finally threw in the towel after 20-some minutes and ran out the rest at a super easy pace.

I am wracking my brain for why I suddenly cannot hold a pace I literally did the weekend before for 3 miles straight at the end of a 9 mile run. The only thing I can identify that has changed is the Diamox, but I don't know if I'm just making excuses and I should be looking at my training plan or nutrition or something else. I googled but most articles are about Diamox effect on performance at altitude, and I'm at sea level, so I thought I'd turn to the collective experience, knowledge and expertise of slowtwitch. Anyone else experience this or have any insight?? I know I can ask my doctor on Tuesday, but she's an ophthalmologist and doesn't know or care anything about endurance sports.