In Genghis Khan's army cavalry archers were trained from childhood to hold on horse by strength of legs (must be hip adductors) on high speeds, so their arms were free to shoot, when it's even hard for many people to hold on horse with all the equipment, so I ask how strong all those tiny muscles like shoulder rotators, foot eversion muscles, hip abductors or tibialis anterior can become?
Also one guy I know did some arm wrestling training, and after that he was able (in judo wrestling) to loosen opponents' grip on his wrists and sleeves by turning his arm inwards (with strong shoulder and wrist rotation muscles) which gives him time to get rid of the grip completely and do other actions. Also, "low kick" in martial arts is propelled for a big part with hip and foot rotators. Those equilibrists walking on thin ropes under circus ceiling, or holding on many indo boards at the same time, etc must be having strong foot eversion and inversion muscles and many others.
I know that some train these muscles as "prehab", even in American football teams, so is there a reason to train these muscles at least for injury prevention while training martial arts, in gym etc?