Key Muscles for Weightlifting
Andrew Charniga, Jr. Do not reproduce or republish in part or in whole without the expressed consent of the author. © 2001
Changes in the technical rules affect the evolution of technique

Key Muscles for Weightlifting
Andrew Charniga, Jr. Do not reproduce or republish in part or in whole without the expressed consent of the author. © 2001
Changes in the technical rules affect the evolution of technique
In 1924 the International Weightlifting Federation altered the competition protocol by excluding single arm lifts and introduced the three - lift program. This lasted until 1972. With fewer exercises to practice, a gradual evolution in weightlifting technique took place. Consequently, accompanying this evolution, the relative role of the strength of the major muscle groups involved in lifting the barbell changed.
The efficiency of lifting technique evolved from the "splot" and split method of descending under the barbell to the deep squat. Accompanying this evolution, the relative importance of the muscles of the upper extremities in the technique of lifting diminished; those of the lower extremities increased.
In 1964, the technical rules were changed to allow the bar to touch the thighs during the lift, i.e., the thigh brush became legal. With this change, the importance of the muscles of the legs dramatically increased. The final rule change effectively reducing further the importance of the muscles of the upper extremities was the elimination of the press in 1972.
With the rule change of 1964 permitting the barbell to brush the thighs, lifters were able to focus on fully utilizing the body's strongest muscles (the extensors of the legs and trunk). Subsequently, the technically proficient athlete would be able to lift a heavier barbell to a lower height, with less reliance on the weaker, bio - mechanically less adept (for lifting maximum weights) muscles of the upper extremities.
The enhanced role of the hamstring muscles in technique
With this in mind it is appropriate to consider this well made point: "All one needs to understand weightlifting is Newton's third law of motion"(12). Simply put, Newton's third law states: for every action there is an equal and opposite reaction. For the weightlifter this means it is necessary to push against the floor with a force that is significantly greater than the weight of the barbell. The resulting "reaction" from the floor is transmitted to the barbell.
The muscles most important to accomplish this effectively are undoubtedly the quadriceps. However, the strength of the hamstring muscles is crucial to fully exploit the strength potential of the quads and ultimately the vertical force that the athlete is able to impart to the barbell.
The hamstrings play a crucial role as antagonists to what must be recognized as the main muscles used for weightlifting - the quadriceps. It is essential to understand how the hamstrings are involved in the execution of the snatch and the clean to best exploit their potential. Since these muscles cross over two joints they perform two basic functions: to extend the hip and to flex the knee.
The hamstrings are initially brought into play as the shins assume a vertical position during the first phase of the pull. As the shins move from an inclined to a vertical position in the second phase of the pull, or the preliminary acceleration (13), the hamstrings are lengthened and subjected to a growing tension. This is because much of the stress of lifting the barbell shifts from the muscles in front of the thighs to those in the rear.
When the shins have ceased to straighten, the hamstrings function to stabilize the hip and briefly act to straighten the trunk. It is against this back-drop (assuming hamstring strength is sufficient) that the lifter is able to create conditions for the most effective execution of the next phase of the lift - the final acceleration, or the "explosion".
According to R. A. Roman (14), as a result of the growing pressure along the thighs (due to the extension of the legs), the knees subsequently shift forward and down. The hamstrings are strongly involved in this action performing their main function - to flex the knees (4,11). This shifting of the knees forward and down under the bar is a reaction.
The growing tension on the hamstrings, combined with the quick lengthening of these muscles as the shins straighten, facilitates the subsequent shifting of the knees under the bar. Indeed, the faster the hamstring muscles are stretched the faster and more powerful the subsequent contraction. This in turn means the quadriceps will be subject to a rapid stretch, which results in a more powerful and faster contraction from these muscles. The end result is a larger force generated against the support (2,4,6,18). The rapid switch from stretching to contracting also produces more power in the jerk from the chest, "the faster the switch from stretching to contracting, the more powerful the force produced" (10).
Hamstrings muscles and the "stretch reflex"
Alexander Lukashev (3,17), believed the lengthening - to- increasing - tension of the hamstrings which occurs in the first phase of t