Horseback riding is one of the oldest sports in the world and fulfills every definition of sport, yet it is often perceived as an easy activity, not a sport. This could be because the only exposure most people have had to equestrianism is television and movies. What the average non-rider doesn't see is the hours of practice and the sore muscles, bruising, and chafing—not to mention the mental challenge—that riders undergo to make it all look easy.
The Australian Sports Commission defines a sport as “a human activity capable of achieving a result requiring physical exertion and/or physical skill, which, by its nature and organization, is competitive and is generally accepted as being a sport.” By that definition alone, there is no doubt that horseback riding is a sport. Let’s look at how it fulfills that definition.
Sport often means there is a competitive side to an activity, and horseback riding definitely provides the opportunity for that. Even if it appears that the horse is being judged, the horse is rarely better than the trainer or rider who prepared it. It still takes hours of human physical activity until a horse is competition ready. There is a huge list of competitive disciplines in the horse world, and success in one doesn't mean a rider will be good in another, any more than a downhill skier could automatically expect to be equally skilled in cross-country skiing. However, all require a level of fitness and skill.
Sports require and build fitness: muscle strength, balance, flexibility, agility, and overall body awareness. Even after a short ride, non-riders will notice certain muscles will be quite sore. Riding requires a few muscles that aren't often used in other sports. The control it takes to use rein, leg, and seat aids to influence a horse requires refined body awareness somewhat similar to a gymnast. While it's not necessary to be a bodybuilder to ride, dealing with an animal many times larger than yourself does require some physical presence.
Skill, strategy, reasoning, memory, and confidence are required in most sports, and it is no different for riding. Memorizing dressage tests and jump courses, following trail maps, choosing the safest route on a trail ride, deciding the most effective way to handle a horse that is exhibiting unwanted behaviors sometimes requires split-second timing, Always being aware of what your horse is thinking requires strenuous mental exercise. Football players may spend weeks memorizing a play. Riders also memorize how they will ride a particular course or cue a horse for a specific move, often within minutes of competing. However, they also need to be mentally flexible enough to change course instantaneously if the horse misbehaves or spooks, or if somehow the playing field suddenly changes.
Trot a few circles, and you'll also find that horseback riding is an aerobic activity. Very few riders just solely ride horses. Ancillary equine caretaking activity such as grooming, stall cleaning, and carrying hay bales, water buckets, and feed bags all require some physical exertion.
Rules and Regulations
Sports are often governed by strict rules and may be played at an amateur or professional level. Open the rule book of any equestrian discipline and you'll likely find a very strict set of regulations that not only outline the rules of the game but also may include rules about clothing, saddlery, bits, the size or type of horse, and many other details.
If you're still not convinced horseback riding is a sport, you should take a riding lesson with an instructor who understands your opinion. After a very short time, you might agree that horseback riding does indeed fulfill the definition of a sport.
"What Is Defined as a Sport?" Australian Sports Commission, ASC recognition.