In many parts of the world, hobby horses are for women, work horses are for men. To get an estimate of the sex composition of any discipline, get out your pencil and count the number of males and number of females you see in Google Images when you search for various words or phrases.
To see if women own the world of hobby horses, search for “pleasure horse” and “work horse” in Google Images. Rider sex is not evenly distributed across disciplines. Disciplines such as dressage, show jumping and trail riding differentially draw males and females.