In all probability, you’re already using a medicine ball in your gym or training facility. You’ve probably got some basic drills, plus you just like to have fun throwing the thing around. In most settings, med balls are used for core conditioning, but there are actually many ways to use them.
hard ball
This most obvious use is for no-nonsense strength conditioning; we might call this macho med ball. The goal is to build power in your torso, arms and legs. Use a heavy ball and heave it at your partner with as much power as he or she can handle. On the receiving end, take the throw straight on and absorb the energy with muscle. Be strong and tough. Work from a good stance and feel the power in your hips, legs and abdomen. Then return the throw. This is good work.
oblique ball
Oblique ball is also a strength event, but now you’re working diagonals. Your arms are acting as lever arms that transmit power to and from your torso. The whole idea here is to work your abdominal obliques. The basic move is similar to the woodchop. Look for a diagonal throw to your partner and squeeze your abs on both the throw and the receive. If you’re doing it right, your torso will get pumped.
soft ball
Aiki ball is an entirely different kind of movement. The goal is not to exercise power, but to practice the subtle art of non-resistance. Receive the throw, but without conflict. Blend with the pass. Catch the ball, but create an arc that redirects the energy and returns it back into your throw. Specific instructions are difficult because there are so many possible adjustments and arcs; you'll just have to try it. (This practice is best conducted outdoors and well clear of obstacles. It takes some time to learn the trajectory of your return throws, so be ready for errant passes)
the aikido connection
You can even imagine that the med ball is a punch attack or a knife strike. The first priority: get your body off the line, get your torso out of the way. Receive the attack by making the movement your own. Get inside the path of the attack and adjust its trajectory to meet your needs.
This type of med ball practice won’t build fitness in the conventional sense. You won’t really build core strength or power. But you will increase your physical intelligence, especially your sense of position and your total agility.