Even elite athletes with Parkinson’s have less of a mysterious exercise-linked protein in their blood than less active peers with the same condition.

The study linked in the post found that people with Parkinson’s who train like endurance athletes—think marathoners or triathletes—have noticeably lower levels of a protein called irisin in their blood than those with Parkinson’s who aren’t as active. That’s surprising because irisin is usually linked to the benefits of exercise, so you’d expect athletes to have more, not less. The researchers didn’t explain why this might be, but they did confirm the difference was real and consistent in their group. It’s a small, specific group of highly trained individuals, so we can’t assume this applies to everyone with Parkinson’s. Still, it opens a weird and fascinating question: is there something about extreme, long-term training that changes how the body responds?