In this video I break down the most common reasons your thumb hurts when you bowl, and almost all of it comes back to fitment. The big one I see is nail damage—white striations or bruising under the nail. When that’s happening, it’s usually a span that’s too long or pitches that are too far under, which loads your nail bed with pressure. I also talk about side rubbing and that pressure point on the back of the thumb. Most thumbs aren’t perfect circles, and a round thumb hole can leave too much room front-to-back, which makes you grip the ball to hang on. That’s why I’ll often suggest an oval thumb hole so you have room on the sides, but the front and back can be a little tighter—less grabbing, cleaner release. If you only rub on one side, pitching toward the rub area can help relieve that pressure. Finally, I cover bevel and sharp edges at the top of the hole, plus the classic “poop thumb” bruise on the thumb pad. That one is almost always from squeezing—your thumb is getting yanked across the top of the hole on the way out. If any of this sounds like you, go talk to your local pro shop operator and get the fit corrected the right way.