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 the pull had great significance with respect to the amount of force the athlete could generate against the support. He reportedly observed that former Soviet lifter A. Rappaport (110 kg class, 202.5 and 232.5 kg results) would atypically execute this part of the lift. Rappaport would cease to straighten his knees in the first phase of the pull, briefly stop; then, in a motion so fast as to be invisible to the naked eye, slightly straighten the legs further before the knees would shift under the barbell in the "explosion".
The so - called "stretch reflex" is an innate mechanism which enables the athlete significantly elevate the power out - put from the muscles involved in executing quick ballistic movements. This phenomenon has been well documented in the literature (7,8,11,15,18). However, making optimal use of this innate mechanism is not well understood in the practice of weightlifting.
Coaches even at the international level implore their athletes to fully straighten the legs and the trunk; and, "shrug" the barbell up. Presumably, the lifter is to execute this action long after, and long past the point of diminishing returns, i.e., after the barbell has already achieved maximum velocity (6).
In the approximately one second it takes to execute the snatch, for instance, it is impossible for the human organism to effectively focus on any such action. When a lifter actively attempts to fully straighten the legs and trunk, rise onto the toes and shrug the shoulders in order to lift the barbell higher, the very nature of this action is detrimental to the lifter's actions which have preceded it and to those which must follow.
According to Zhekov (6), "During the formation of technique, the lifter will find ways to increase the speed of the barbell by making repeated use of the 'already' working thigh extensor muscles". This is why the relative strength of the hamstring muscles, and indeed that of the other muscles of the thigh which flex the knees, is so important. The speed with which the athlete switches from straightening the knees to bending and, once again, straightening, then bending the knees during the snatch and the clean has a profound affect on the technical efficiency.
Research of muscle antagonist pairs and speed of movement
A high correlation was found between the strength of the hamstrings and the vertical jump results of weightlifters. Furthermore, the vertical jump results of weightlifters have a high, but inversely proportional connection to the speed with which the knees shift under the barbell. The stronger the hamstrings, the higher the vertical jump of weightlifters, the faster the knees shift under the barbell in the "explosion" (4).
The faster this reaction takes place, the more powerful the "explosion", the higher the results.
Research into improving the speed of joint motion has shown that the relative strength of the antagonist muscle in an antagonistic pair can affect the speed of movement (1). The hamstrings are the antagonist muscles to the quads. These muscles act as a "brake" for the quadriceps during the extension of the leg. This is to keep the joint from being straightened faster than it can be prudently stopped.
According to the research in this area: " When the agonist is stronger than the antagonist, the neuromuscular system limits speeds to that the antagonist can safely brake, even if the agonist can make the joint move faster" (1).
Consequently, the recommendation "To make an athlete move faster, training must emphasize the antagonist"(1). In all probability this is the reason for the practical observation in weightlifting that "A lot of squats adversely effect speed"(16). A significant disproportionate strength development between the quadriceps and the hamstrings is, apparently, the reason behind this observation.
The key role the hamstrings can play in weightlifting technique revolves around the so - called stretch reflex and the positive effect the action of these muscles can have on the vertical forces produced by the quadriceps. In the approximately one second it takes to execute the snatch, the hamstrings are stretched and subjected to significant tension as the legs initially straighten when the barbell is lifted from the floor. Then, in virtually the same instant they come into play to flex the knees as they shift under the bar. Finally, a fraction of a second later, the hamstrings flex the legs for the squat under the bar.
According to N.A. Bernstein "The movement of the body is more economical, and consequently more rational, the greater degree to which the organism utilizes the reactive and external forces and the less reliance on recruiting active muscles" (6).
In weightlifting, the technically proficient athlete makes full use of the extra force he is able to generate from the stretch - reflex. The athlete actively coordinates the body's movements to take advantage of the elasticity of the bar. The internal forces referred to by Bernstein are produced by the stretch - reflex. The extra power produced from this mechanism is coordinated to take advantage of the external forces - the elastic rebound of the bar.
If the lifter focuses on the most effective element of lifting technique, rapidly generating force into the platform, he will be able to make better use of the so - called "reactive" forces.
Weightlifting technique has evolved over time as a result of the practical experimentation of the athlete and the changes in the technical rules of weightlifting competitions. Even the physique of today's elite lifters is a reflection of the shift in emphasis to the muscles of the lower extremities and away from that of the upper extremities.
The rule change of 1964 in particular, allowed the athlete to fully exploit the innate physiological mechanisms (the stretch reflex), heretofore, not unknown, but unrealizable within the limitations of the old technical rules.
The strength of the hamstring muscles relative to that of the quadriceps plays an integral role in technical efficiency. The faster the athlete is able to switch from straightening, to bending, to once again straightening and instantaneously bending the legs during the execution of the snatch and the clean, the more effective the technique.
All thing being equal, the most effective method of ensuring the harmonious development of the quadriceps/hamstring antagonist pair for weightlifting technique is do the classic snatch and the classic clean and jerk. However, one should consider devoting a portion of the training time to strengthen the hamstring muscles, because of the natural overloading on the quads that comes from squats.
Here one should emphasize movements where the feet push - against the support, i.e., mimicking the actual way the muscles are used in the lifts.* Johnny Schubert, the famous coach of two - time Olympic champion Chuck Vinci, even went so far as to recommend that lifters should do one repetition of hamstrings exercise for every repetition of squats (19).
In the pull phases of the snatch and the clean, focus on pushing down as hard and as fast as possible throughout the movement so as to create the best conditions for the "explosion" phase and the squat under the barbell.
A powerful, initial effort from the floor and subsequent maximal - effort to accelerate the barbell sets up the advantageous chain reaction of a rapid stretch/tension in the hamstrings, triggering a rapid flexing of the knees. This in turn causes the knees to flex under the bar with less amplitude, which, in turn, triggers a faster more powerful straightening of the legs with the resulting greater force against the support (4).
It has been suggested that elite lifters lift the barbell from the floor slowly, on purpose. This technique allows the lifter to reserve his maximum effort until the beginning of the "explosion" at which point the barbell will be in a position for the lifter to be able to generate the greatest force. Presumably, the barbell must be moving at relatively slow velocity in order for the lifter to have the time necessary to generate a large force against it (15).
This should not be considered the optimum technique, because it reduces the automatic utilization of the so - called "reactive forces" and divides the pull phase into separate efforts to lift the barbell. Purposely waiting until the bar passes the knees in order to save one's maximum effort for this positioning of the body's levers, wastes time and mechanical advantage. Consequently, the subsequent effort needed to generate the large force now required because the barbell would be traveling at a lower velocity on purpose, would be excessive relative to the overall coordination structure of the exercise.
*This does not include the so - called "Romanian deadlift". Let it be known, that there is not now, there never has been, and there never will be a "Romanian deadlift". In all probability deadlifts were invented long before there were Romanians on this planet. So, whatever, variations are possible, each one does not deserve a special name which by its very nature would seem to indicate that it is some special innovation relative to what is merely a bending and straightening of the torso.