Referred to as an “equestrian triathalon”, three-day-eventing is an extreme sport that tests the talent of both horse and rider, including three phases: dressage, cross-country, and stadium jumping.
DRESSAGE is on the first day of the competition and is very important to the three-day event horse. It helps to develop the muscular strength and suppleness needed the other two days of competition, endurance day and show jumping, where the horse must be unbelievably fit and strong, and able to lengthen and shorten stride at a gallop. The rider has to memorize a prescribed test, according to their competition level, and perform with the horse in a dressage ring that has letters marked around it. At these letters, the test will tell what movements to perform, and the judges give a score of 0-10 on each individual movement. The scores are added up, then subtracted from 100% to give u a score that portrays your penalties, so you want to achieve a low score. The purpose of the dressage test is to demonstrate the level of communication between the horse and rider and display the power and grace required to perform each movement with balance, rhythm, and suppleness. Due to the demands of the sport, the three-day event horse is extremely fit, and only strong and tactful riders possess the skills needed to harness and direct that energy into a both polished and powerful performance.
The CROSS-COUNTRY test on the second competition day proves the speed, stamina, courage, boldness and jumping ability of the horse and the rider’s knowledge of pace and use of the horse across country. The cross country course is over natural terrain a few miles long, depending on competition level, including massive natural obstacles. Cross-Country is straightforward – the horse and rider either clear the obstacle or they don’t, and they either come in under the galloping speed optimum time or they don’t. Horses galloping at speed over massive solid obstacles, virtually flying over ditches, leaping up and down banks, and dropping into water prove examples of athletic prowess, and trust between man and animal, that can be seen in no other Olympic sporting event. While the rider walks the course beforehand, the horse doesn’t see any of the course until it leaves the starting box. The object is to keep your dressage score the same, adding no penalties to it. This is accomplished by coming in under the optimum time, and having no jumping faults (running-out or stopping at a jump is an extra 20 penalty points each time). If the pair has 3 stops at a fence, or 4 stops total on course, they are eliminated, and also if the horse or rider falls, the pair is eliminated and must exit the course immediately. 
SHOW JUMPING in an arena on the third day comprises a series of colored fences usually made up of lightweight rails that are easily knocked down. The test takes place in an enclosed ring and the course must be negotiated in order for the horse and rider to successfully complete the event. This final phase tests the stamina and recovery of the horse after the endurance phase and shows that it is fit enough to continue work. The courses are designed to test the horse’s and rider’s ability to negotiate a variety of fences of differing heights, widths, and technicality. This requires the horse be balanced and supple for tight turns and short distances between fences. He must be able to lengthen or shorten his stride in an instant. A single rail knocked down can make the difference between winning and finishing far down in the placings. The object is to not add any penalty points to your previous dressage and cross-country scores, by coming in under time and not knocking any rails, or having any stops at the fences. Every stop or rail knocked is 4 penalty points, if a horse has two stops they are eliminated, and if a rider falls, it is elimination.
