Training and conditioning with the Keystone Concept can be very beneficial.  In order to get the most out of your D-Balls, please read this section on how to prevent injury and different ways to use the D-Balls to build power and strength.
How to Prevent Injury
Never lock knees because it destabilizes a body in motion and leads to weaken power or possibly injury.
To prevent risk of injury when a ball is thrown to you, do not catch the ball. Instead, allow the thrown ball to land on the ground or do a semi-bounce before picking it up.
Ways to Train and Condition with D-Balls
Holding a D-Ball:  Grip the D-Ball with palms at the 4-ridge circumference and hold continuously away from the centerline of the body and hold continuously away from the centerline of the body. Any other hand placement or elbows locked at sides reduces the workload on the shoulder and core group. Gripper is held with palm down and elbow slightly bent.
Squatting and Moving:   From a squat position, hold ball in front of toes off the ground to engage core and lift hips and ball as a unit. Hold ball in front of toes off the ground to engage shoulders and core. The body’s motion during the lift is exactly that of free weights. Use hips to lift ball from low squat position. Hips and ball move together as one unit: the hips and core do less work when hips come up to a ½ squat position and then ball is lifted.
While standing hold Keystone ball at arm’s length < 90 degrees out from body, holdthe 2x Key D-Ball with elbow bent and the 3x Key D-Ball at arm’s length very close to the body.
Single arm and leg drills balance right and left side strength and stabilizer muscles. As an example of a Super Set: hip flexion / extension with the Keystone ball on leg by knee or with a Gripper D-Ball in each hand tracing the alphabet, circles and fly’s.
Throwing Drills: the most difficult exercise to do with a medicine ball is to catch it, especially when another person throws it. The faster the throw speed the more dangerous it is. Throws are initiated with the hip muscle group like the push press.
Slamming Throws: start with a D-Ball behind your head and have elbows pointing towards ceiling, then throw the D-Ball straight down.
Ballistic Throws:   Using an Orange D-Ball which has a user-friendly semi-bounce, do a hard throw which will result in a good semi-bounce. All the effort can be put into this type of throw because the semi-bounce back is slower, therefore, catching isn't a self-defense priority.
Plyometric Throw / Catch / Throw:
IMPORTANT: Allow a ball to land on ground before catching because it is safer and will prevent injury.

1. Catch and lift
2. Step down
3. Catch and lift
4. Jump down and catch
5. Jump up and lift
6. Hold out from chest,
7. Jump and lift