There has always been a strong connection between horse riding and fitness, after all horse riding itself is a form of exercise. Core strength is what’s required to really feel the connection between yourself and your horse. The stronger your core is the more correctly and effectively you use your leg, seat and hand aids to communicate with your horse, and the better he will perform.
Many riders don’t even realize that they’re unconsciously sending their horse confusing and contradictory signals and messages. Remember, horses are creatures of habit. Whenever you change how you apply an aid, it will take many repetitions for your horse to learn to respond properly to it. Similarly, your own body will need plenty of repetition to develop the muscle memory and strength required to perform these new skills correctly.
Yoga and Pilates are proven to dramatically improve your core strength and posture – both are ideal forms of exercise for any horse rider. Even if you don't practice yoga regularly, holding a few key positions, like the boat, half-boat, or warrior for a few seconds a day will help. Also, try holding the plank position even if it’s just for a couple of seconds to begin with, you’ll soon build up to a minute or two and you’ll notice a difference in your core almost immediately!
As an added bonus, doing these moves correctly can also strengthen your back and improve your posture. These also help open up the shoulders which is good for people who do a lot of slouching.
In order to have an effective working relationship with your horse it is necessary to have even toning all over your body so don’t neglect other muscle groups. Practice doing some upper body exercises such as push ups and the plank, and try using free weights as well - you can start light and work your way up. Many top level riders have a small set of weights which they will lift several times each day to maintain upper body strength.
There have been many studies into the benefits of yoga and core strength for horse riding, Charlotte Dujadin herself announced at Your Horse Live how integral it is for improving your seat on the horse, flexibility and stamina.
Finally, always remember to stretch before and after you exercise. Take time to warm up and to cool down. Focus on stretches that target your groin and thighs, such as the butterfly stretch, to stay flexible and reduce stiffness. Be sure you do all of your stretches slowly and carefully.