This post is on moving our COM (centre of mass) during training and assessment.
During sport and many functional activities such as walking we are constantly moving our COM. Walking is about controlling the change in position of our COM that comes about from the bodies momentum carrying it forward once it gets moving! Try and throw a ball without shifting you COM from the back to the front. The same is true of throwing a punch or hitting a tennis shot. By transferring our COM we are putting the M (mass) in F=MA, Newtons second law of motion that deals with acceleration and ultimately force production. The more mass we can accelerate the more force we can produce. If we threw with just our arm that mass would be small. By moving our entire COM that mass becomes much larger and so does the force we can generate.
The question is do we use transfer of COM in our training and assessment??? A step beyond that is do we displace our mass in the horizontal e.g forward and back, rather than just in the vertical e.g up and down.
How many traditional gym exercises move COM. Well quite a few. Deadlifts and squats both do in the vertical (up and down). How many in the horizontal (forward and back) erm....not so many!! How many of the movements discussed above use forward and back COM transfer for power...all!!! So when we are training for sport really we should be looking to train COM movement away from just the vertical. Does that mean the clean and press is not going to help us punch harder or throw better??, I think that's exactly what it means! We have to examine the functional crossover of our exercises rather than just apply gym based exercises to any sport or function feeling they will have crossover to generic 'strength'
What is described as timing in sport such as when we hit a great shot in cricket or tennis is being able to move our COM at the perfect time in the right direction to impart the most force on the ball!!
Many times during assessment our clients will be able to translate their COM forward effectively on one side but use rotation on the opposite side as they are unable to decelerate the COM transfer in the hip or ankle joint. It is much easier to rotate in the sagittal plane into flexion using gravity and keep the COM central rather than moving the COM forward through translation. A simple test is to see whether a client can lunge forward effectively in the horizontal vector without sinking downwards towards the floor. This would show effective transfer of COM. If we do not look to move COM in assessment we cannot tell if the joints and muscles in question can decelerate our mass and resultant momentum vital to functional success.This deceleration will lead to effective acceleration as we eccentrically load the muscle for concentric force production.
In fact effective horizontal translation in the sagittal plane will increase motion in the transverse plane at the hips and therefore the feet and spine too!
Using 3 dimensional space will force our bodies to shift COM, decelerate and harness momentum for force production. Most traditional exercises keep us rooted to the floor!!
Think outside the box for functional success!!!