A doctor explains why a spin class or similar can result in blood all over your panties from anal bleeding.

Have you ever gone to the restroom following a spin class, pulled down your underpants, only to nearly have your eyes pop out at what you saw—fresh blood smeared all over your underwear?

“Spin class or intense prolonged use of a stationary bike may cause anal bleeding through direct and indirect mechanisms,” explains Steven Fleisher, MD, chief of gastroenterology at the Center for Digestive Disease at MedStar Franklin Square Medical Center.

“Direct mechanisms would include irritation to the anal, and peri-anal skin through prolonged pressure, especially if one remained in the saddle for prolonged periods of time.”

Anal bleeding once happened to me.

It wasn’t a spin class, but I was on a stationary bike doing high intensity interval training.

By the time I was done, the bike had moved a few feet along the floor.

I hadn’t used a stationary bike for an extremely long period of time. I made a trip to the john, pulled down my white panties, and lo and behold…red blood stains all over the inner portion of the garment. I immediately connected the dots.

This is the only time I’d ever experienced anal bleeding from cycling, and I believe it was due to a combination of not having been on a stationary bike for a very long time, and the fact that this particular machine jostled quite a bit as I pedaled.

Prevention of Anal Bleeding from Cycling

Dr. Fleisher explains, “Here, using the correct apparel such as riding briefs with a chamois may be important.

“In addition, any pre-existing peri-anal conditions such as warts, or hemorrhoids, may be further inflamed, and bleed.

“Indirectly, prolonged sitting is one of the factors that predispose to hemorrhoid formation, which in turn may cause bleeding.

“There are several theories about how hemorrhoids actually form that include changes in tissue integrity, increased anal tone, and swelling of the hemorrhoidal cushions (veins).”

Dr. Fleisher was named a 2015-2018 “Top Doc” by Baltimore Magazine for gastroenterology.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.