Quarter horses have an extremely powerful core. They have an extremely muscular neck and can accelerate at an astonishing velocity. This structure is also an excellent foundation for a strong jump. The horse's powerful hind legs allow for a world-class leap with plenty of height and speed. A good jumper needs to be fast, strong, and flexible. A good rider helps the horse by being calm and relaxed in the box. She/he should not force the horse into a premature move but rather let it go when it is ready. A good rider also keeps his or her seat during the course of the jump. This shows that there is trust and respect between horse and rider. A bad rider forces the horse into unnatural movements which may cause injury to the horse or herself. Good quarter horses are usually found in countries where the sport is popular such as France, Germany, Spain, and America. There are many types of competitions for jumpers including local events, national championships, and international contests. In order to become better riders and earn higher scores, they must compete against other riders and their horses. The quality of the horse's breed does not necessarily mean better results; however, it does play a role. Quarter horses are known for their endurance so they must be able to stand up to long distances without getting tired. They are also required to have smooth muscles since they often jump over large objects.