horses reluctant to trot , horses act smart in the track

Question
hello madam,
1)why few horses are reluctant to trot when they enter into the track during workouts. how badly the rider is forcing the horse to move, still he walks, not trots. then, what should the rider do to trot the animal??

2)madam, another doubt, few racehorses try to act smarter and play with the rider when they enter into the track in the morning workouts. may i know why??

Answer
1. the horse is more then likely sore and does not want to run. it should be rested. racing is very hard on their legs
2. the horses are bored with the routine. would you want to run in a circle everyday??. try to mix things up and keep the horse busy with new things