Here are a few of my favourite exercises for getting your horse supple and stretching his back out. These exercises are what I use for both my showjumpers and can be done as a warm up in walk and trot for younger horses as the main focus of a flatwork session.
Turn on the forehand
This exercise entails riding a square where the corners will be where you do your turn on the forehand. For your first few corners halt, ask your horse to bend to the inside while holding your outside rein so as to prevent him from just turning in. Put your weight on your outside seat bone (put more pressure on your outside leg) and bring your inside leg back ask your horse to move his quarters around into your outside hand so that you are facing the next side of your square. Do this slowly if you’ve never done it before, going one step at a time is fine! make sure your leg and hand pressure are enough for your horse not to move forward or back, or around with his front legs. Later progress to just slowing your horse down in the walk into the turn on the forehand.
This exercise is most effective in canter as it really stretches your horses back out but progress from the walk first. Start with a 15-20m circle. For about half the circle ask your horse for an outside bend keeping on the circle. I say half a circle but it should be until he softens into the bend. Release the bend so that he isn’t bending in or out and then ask for a normal inside bend. Repeat this a few times until it starts becoming easier.
Circle in, Leg yield out
The name is pretty self explanatory. Start by riding a 20m circle in the walk (later in the trot or even canter) getting a good inside bend around your leg. Circle in to as small a circle as you can, usually about 6-8m, keep on the smaller circle until your horse has softened with a deep inside bend. Once your horse supple’s, leg yield, slowly, back to the 20m circle track by putting your weight on your outsides seat bone, applying your inside leg and keeping your horse straight. For younger or stiffer horses straighten after a few steps of leg yield so as not to push your horse causing him to evade your aids.
Leg yielding a square
This exercise combines the turn on the forehand and leg yielding. Ride your squares as in the turn on the forehand exercise but instead of walking straight along the edges of your square ask for one or two more steps in your turn on the forehand and then continue along the ‘straight’ in leg yield at a 30/40 degree angle keeping your weight on your outside seat bone.
With all these exercises start slowly giving your horse time to straighten after each exercise but never let him get too long and disorganized between exercises otherwise it’s difficult to pick things up again. Be patient and always urge your horse to soften into the exercise, no extreme force should be involved no matter how frustrating things get.