There are four important angles that are key to correct riding. Those four angles include the elbow, hip, knee, and ankle. Using these angles effectively allows you to give subtle aids to communicate with the horse.
Physical Fitness
In order to move and ride well it is important to be fit. An effective rider has independent use of the arms, hands, and legs allowing effortless communication with the horse. Every joint should work like a smooth hinge. Luckily for us, riding in and of itself is a work out, however to be able to use the muscles you need for riding you must ride often, very often, which requires the use of multiple horses. For many riders this is not possible, but by sticking to an exercise regimen of running, weight lifting, stretching, Pilates, or Yoga you can receive a similar workout.
Elbow
The elbow is essential in controlling your horse’s direction, speed, and head carriage. How open or closed this angle is depends in part on your own conformation and what you are doing with your horse. This joint allows you to follow your horse’s mouth with your hands and arms. In the proper position your elbow will be relaxed, slightly bent, and held a little in front of your body. Your hands will be carried over and slightly in front of the horse’s withers. Your wrists should be straight so that the back of your hand is even with the top of your forearm, with your hands matching the slope of the horse’s shoulders. There should be a straight line from the bit to your elbow with a soft contact on the reins. Your arms and hands should be soft and following. Stiff arms equal a stiff horse.
Hip
The hip angle in english riding, especially jumping disciplines, is referred to as being open or closed. When sitting upright in the saddle, as you would at a halt, with your back straight in a vertical position your hip angle is open. The hip angle is closed when you lean forward at the waist. The most common times you would close your hip angle is when your are in a half seat and over jumps. When your hip angle is closed your upper body bends forward at the hip, placing your upper body about 30 degrees in front of the vertical.
Closing your hip angle will get your seat off the horse’s back, making it easier for him to move and allowing you to stay with the motion. Your seat should be out of the saddle with your upper body inclined forward when galloping. The horse will close your hip angle for you with the effort he makes while jumping. Other wise, at the canter and sitting trot your upper body should be slightly in front of the vertical, with your seat still in the saddle.