Many golfers, baseball players, tennis players, and other athletes who must swing an implement or throw an implement for distance or force believe that rotation of the hips shifts weight onto the forward leg. However, rotation of the hips, trunk or total body does not shift weight. It can only redistribute the amount of weight supported by different parts of the feet.
The reason for this is that when you rotate with the axis in the spine you have as much weight moving backward as there is moving forward. Thus the amount of weight remaining on the left or right leg remains basically the same. If you rotate the hips (and shoulders) using the spine as the axis of rotation, you will not get forward weight shift, but you will produce force to hit the ball.
Weight shift is a very distinct action and contributes additional force. When sequenced with hip and shoulder rotation, it produces much greater force to hit the ball — up to 20-30% further. To shift your weight forward you must move the pelvis (the hips) forward since this is where your center of mass is located, i.e. , the point where all your weight is considered concentrated.
When you put this body part into motion, your body is considered to be in motion. You can have as much force generated in moving the hips forward as when you move your entire body forward as a unit. This is a tremendous amount of force that can be produced with a relatively simple action – right hip joint abduction for the right-handed athlete.
Shifting the hips forward to move your weight onto the front leg is also important for setting up a new axis for rotation of hips. When the axis is in the front leg, the entire hip rotates forward, creating twice the amount of force generated by the hips when the axis is in the spine.
By first shifting the hips forward and then rotating the hips in sequence you will be able to generate much more force than simply rotating the trunk without the weight shift. This action also helps set up a smooth transition into the remaining body actions in the total kinetic chain.
To learn and to improve the weight shift action to generate more force in the swing or hit, do the hip abduction exercise with Active Cords. In this specialized strength exercise the hips are in motion to duplicate the action of shifting the hips forward as occurs in a swing or throw.
However, you need Active Cords to duplicate this action. The cords have a nonslip belt that allows you to attach the resistance directly to the hips and execute the weight shift in the same manner as it occurs in execution of the swing or throw.
In addition, you can also improve the strength of the hip rotation muscles by doing specialized strength exercises with the Active Cords that duplicate hip rotation. When each of these actions are mastered you can then do a specialized exercise in which the weight shift and hip rotation are combined in sequence as occurs in the total throw or swing.
To learn more about the weight shift, hip rotation and hip abduction actions read Build a Better Athlete, Explosive Golf and Biomechanics and Kinesiology of Exercise.