Impact is the point at which the potential energy/speed generated by the body during the backswing, transition, and downswing is transferred into the golf ball. Impact with the ball occurs for approximately half a milli-second. (Fleisig, Biomechanics of Golf) The purpose of impact is to hit the ball in the correct direction with the chosen amount of force. At impact, weight transfer is complete and shear forces from both feet are towards the intended target. The clubhead and ball at impact are in contact for approximately half a millisecond (0.0005 seconds). Any error in timing, positioning of the kinetic chain, sequencing of the swing, or positioning of the clubface will directly affect the impact position, ball flight, speed, and direction.
Biomechanically at the impact position the counterclockwise rotation of the feet is complete. Research indicates at impact the left foot (right-handed golfer) is supporting 80% to 95% of the golfer’s weight. (Fleisig, Biomechanics of Golf) In addition to the percentage of weight shift, research has found the lower handicap golfer had their weight supported toward the heel of the left foot, whereas the higher handicapper supported the weight in the middle of the foot. (Richards, J, Weight transfer patterns during the golf swing) The hypothesis behind this differentiation at impact between the lower and higher handicapper was the skilled golfer obtains more counterclockwise rotation during the swing.
Maximum clubhead speed is intended to occur at the impact position. Higher handicap players due to biomechanical inefficiencies and or physical dysfunctions loose speed prior to impact resulting in a loss of distance and potential ball flight direction.
Execution of the impact position requires the release of the hands with correct timing for the transfer of speed to the club head. In order to perform the wrist release, weight shift correctly, sequence the transfer of energy through the body, and release speed into the golf ball, all phases of the golf swing leading up to this point must be executed correctly. Errors in the kinematic sequence or phases of the golf swing caused by physical limitations, poor mechanics, or improper equipment will affect impact. Physical dysfunctions in terms of mobility, flexibility, stability, strength and/or power development will “show up” at impact relative to ball flight, distance, and direction.