Google AI Overview says:
Marathon categories include distance variations (Full 42.2km, Half 21.1km, Ultramarathon >42.2km) and runner classifications based on age, gender, and ability. ...

Runner Categories
Elite/Professional: Top-tier competitive runners.
Age Groups: Typically divided into 5 or 10-year increments (e.g., U20, 20-34, 35-44, 45-54, 55-64, 65-74, 75+).
Gender: Usually Male (M) and Female (F), with many events now including Non-binary categories.
Para-Athletes/Wheelchair: Specialized categories for para-runners.