Pendulum swing 


When on the apparatus we can develop angular momentum in a fashion similar to the “tripping effect.”  The major difference is that instead of a horizontal force initiating movement, a vertical force is responsible.  That vertical force is gravity.  It acts the same on all bodies regardless of size or weight.  By virtue of a downward force (gravity) and fixing the hands or some other part of the body on the apparatus, we can create a force couple.  Because the hands or other part of the body become fixed that becomes an axis about which the rest of the body (which is free to move) will rotate.

We create what we call a pendulum swing.  It is possible to swing back and forth continuing to build a bigger swing or it is possible to rotate completely around a piece of apparatus.  In either case, we are rotating during this time.  We have angular momentum.  In order to take the greatest advantage of gravity we lengthen our bodies on the down swing.  This allows the center of gravity to fall a greater distance which will give it a greater velocity at the bottom.  We must decide whether the individual has the strength to maintain the fixed contact with the apparatus.  In other words, because of an increase in angular momentum as a result of an increase in angular inertia (either because of large mass or increased length of body), the body will need an increased ability to control the increase in angular momentum.  In order to reduce the inertia at any time, but in particular, on the up swing, we shorten the body the same as we would in the air.  This will increase our angular velocity and help us achieve a complete revolution if desired.  By utilizing the same principles which governed learning to swing on the playground swings when we were youngsters, we can learn to “swing” our bodies on gymnastics apparatus. 

Pendulum Swing is jiu jitsu escape for the competitor from the north south position.

By gripping the belt and pressing upward while simultaneously swing your legs side to side in a pendulum motion. With the constant use of pushing and swinging the oppenent hips will become further away.

 The amount of space created with the pendulum motion will give the defender a chance to escape and recover a dominant position or at least a scramble.

Theoretically, a person could continue a pedulum swing indefinitely without any more effort at the level they started out.  However, friction would continuously reduce the height of the swing until the person came to a stop.  Air resistance might also be a negative factor.  What is it then which causes the person to be able to swing higher?  Since the only force that is available is the effect of gravity, the objective is try to put the body at a higher level in order that gravity has a longer time to act.  In this way the body will have a greater velocity at the bottom of the swing (which is, theoretically, the greatest velocity point during the entire arc) and will rise to a higher point on the up swing.  The only way this can be done is to reduce the angular inertia so that the angular velocity is increased.  The increase in angular velocity will result in a higher peak of up swing each consecutive time until it is possible that a body will attempt to make a complete revolution (something virtually impossible on a playground swing because the chains are not rigid and would collapse after rising beyond a horizontal position).  Since the angular inertia of the pendulum consists of its mass (weight) and its length and, since we can do nothing practical to reduce the body weight itself we have to work with the length of the pendulum.  We reduce the angular inertia by shortening the radius of rotation (bring the body closer to the axis of rotation) on the up swing.  By the same principle then, in order to maximize the effect of gravity on the down swing, we should do just the opposite, i.e., lengthen the radius of rotation by moving the body weight further away from the axis of rotation.

When learning any skill involving swing we should first be concerned with developing the skill pattern with the least amount of swing possible.  The appropriate changes of shape of the body and the correct timing of those changes of shape should be learned first.  As the essential characteristics of the skill are learned, more force can be added to the skill by moving the center of weight further away from the axis of rotation on the down swing.  Since this will produce more angular momentum, there should be a concern for the safety of the individual and a preliminary judgment of whether the individual is capable of maintaining their contact with the apparatus at the bottom of the swing.  Every skill involving swings becomes a process of learning the basic movements with a minimum of swing and then adding swing in order to increase the amplitude of the skill keeping in mind that the more the body is lengthened on the down swing the greater will be the total momentum of the body at the bottom of the swing.

Pendulum Swing