Saturday, July 31, 2010
Friday, July 30, 2010
Thursday, July 29, 2010
Bench Press, Part Six
Bench Press, Part Six
2.7 - The Sequence of Bar Movements Used in Raising the Bar
The differences in bar path used by the expert and novice bench press groups were found to be even more extensive than the horizontal shift of one relative to the other (as discussed in the previous section). The angles used to define the motion of the additional bar from instant to instant during the bench press provided additional insights into the lift. (Please refer to Figures 2 and 3 and especially Figures 10 and 11 of the last section). Note in Figure 11, in particular, the differences between groups for 3 (circled) and 4 (circled). The light expert group (as shown in Figure 11) moved the bar off the chest at an average angle of 60.3 degrees with the horizontal, while the novice subjects average 84.4 degrees for this same angle 3 (circled). This difference in angle was very significant statistically, and raises an interesting question. Does this rapid movement of the bar right off the chest (toward the head) serve to increase the capacity for force exertion when the bar is at the sticking point (by reducing the moment at the shoulder required to generate that force)? Note also in Figure 11 that 4 (circled) results are analogous to 3 circled. Table 7 presents this angular data on heavy expert lifters (from references 7 and 9, Section 1.4).
As shown in Table 7, he heavy expert group has a similar trend regarding the sequence of bar movements to that shown by the light experts. It is important to remember that the significance of the differences for 3 (circled), as well as 4 (circled), between expert and novice groups is magnified when you consider that this marked push toward the head occurs right off the chest (before the bar is but a few inches up!). The important point to remember here is to quickly begin the push of the bar horizontally toward the head right as the bar is first pushed off the chest. To not do so will result in a path not unlike the novice group. I am not saying that one should follow a specific angle off the chest, but rather that every bench presser needs to push MORE toward the head immediately off the chest. It was interesting to note that world class bench pressers I analyzed over time decreases 3 (circled) and 4 (circled) over the years as their lifts increased.
A final point of interest regarding the bench press and competition. It seems possible that a lot of lifters may forget about their technique in competition (or with new personal record attempts in the bench press) and mistakenly push up more than they normally would. From experience, I often find myself thinking more about "blasting" a record bench press weight off my chest than about following a better bar path. When any lifter in this situation sacrifices his technique and "blasts" the bar off the chest his path mimics more the one in Figure 11 for novices, and typically may result in a failed lift. Like in all sports, technique is actually MORE important in maximal, competitive situations. So, try to remember to follow the sort of bar path we've discussed when you're on the platform. It should help.
2.8 - Grip Spacing
In addition to bar path, two factors must be specified to completely describe the bench press technique. The first is hand position on the bar (i.e. grip spacing). The second is the rotation of the forearm and upper arm about an axis through the shoulder and the hand (which will be discussed in the next section, 2.9).
Any bench presser should increase the distance between his hands to further enhance his performance. Although expert lifters demonstrated no significant differences in upper body length relative to the novice lifters, their finishing bar position was significantly closer to the shoulder. The normalized average heights above the shoulder were 0.923 meters and 0.794 meters for the novices and light experts respectively (reference 7, section 1.4). If arm length is proportional to to body length this could occur only if the competitive lifter's hands were placed further apart on the bar than were the novice's. The benefit associated with the increased hand spacing is to help compensate for the increased tricep involvement required by the optimum path described earlier. If the bar is held fixed and the hands moved outward, the elbow moves closer to a vertical line through the bar. This motion reduces the elbow extension movement required. The required tricep involvement is correspondingly decreased. The lifter could conceivably reduce the shoulder torque requirements without affecting the elbow torque requirements by modifying his bar path and hand spacing in a coordinated fashion.
The large expert bench pressers also used grip spacings significantly wider than the novices and analogous to the light experts. For these larger lifters the mechanics of the bench press are affected b the rules of powerlifting. When a very tall individual bench presses competitively, the 32 inch grip width limit works against him since a wider grip would be more advantageous. For very big bench pressers this limit on width roughly approximates a smaller lifter having to "close-grip" his bench presses! Perhaps the rules on grip width can someday be amended to be proportional to shoulder width, height, etc.
As I have just mentioned, yes - I have said here that a wide grip is optimal for bench pressing. My major reasons for supporting this view came from a study that I did with Dr. Nels Madsen back in 1982 (reference 6, Section 1.4). We did a three-dimensional analysis of yours truly performing three types of bench press: (1) wide grip (31 inch), hitting high on chest; (2) wide grip (32 inch), hitting low on chest; and (3) narrow grip (shoulder width - 20 inch), hitting high on chest. (NOTE: the grip spacings here are the distances between index fingers (as in rules), and "low" on chest was base of pectoralis major and "high" on chest was 2 inches above that toward the head). A three-dimensional cinematographical analysis was performed as I did single lifts with 300 pounds using all three styles. In addition, a simplified musculoskeletal modeling approach was used, incorporating the pectoralis major (chest), anterior deltoid (shoulder), and triceps (arm) muscles. These three muscles are by far the major muscles involved in the bench press. Markers on the body and bar were used to track the arm and bar in space during my lifts. Forces required in these muscles to successfully perform the lifts were calculated in several ways using optimization techniques. However, of greatest importance here was the prediction of the maximum force that I could have exerted at my sticking point (or how much I could have maximally bench pressed using each style). We used a variation of the work equation for a fixed direction here, and predicted that I would be strongest in the wide grip styles by about 10 to 23%.
There are several final comments I'd like to make before we leave grip spacing:
1.) As anyone proficient in bench pressing knows, a little change in grip width can cause significant changes in muscle involvement. A wide grip involves the pectoralis major (chest) and the triceps (arm) less, and a close grip does the reverse. The largest muscle by mass involved in the bench press is the chest and it is logical to involve it more, using a wide grip, to lift ultimate weights.
2.) I find that those top bench pressers using narrow grips are few and far between, and more often than not they use a narrow grip because of a former pectoralis injury.
3.) From a mechanical work perspective, the wider the grip the less the distance required to push the bar to completion (and less work required as well). Bench pressers who break world records are typically endowed with (or have well-developed) large chests and short arms. Coupled with a wide grip these people are terrors in competition when when bench press time comes around.
4.) Obviously, a few people can excel in bench pressing with narrower grips, but just think what they could do with a wide grip if they gave it some time. It is important to realize here that narrow grip benchers are tricep and deltoid strong and pectoralis major weak. When switching to a wide grip it is necessary to give yourself some time to get the chest up to par (and for a while your maximum lift will possibly be less with a wide than narrow grip). It just takes some time.
2.9 - Angling of the Arms
The ideal arm position during the bench press is difficult to determine from a two-dimensional analysis. The necessary three-dimensional studies to determine this are presently underway. If the hand is fixed on the bar (which it is) and the bar is not allowed to move, there is still one degree of freedom in positioning of the arms. This freedom is equivalent to a rotation of the arm about an axis (or line) through the hand and shoulder. The range of motion of the rotation during a bench press is small, but critical. The location of the end of the bar and the shoulder cannot be used to determine the position of the elbow. Investigation of the optimal arm orientation during a lift awaits more three dimensional kinematic studies of the bench press.
The angle I have defined is most easily seen (Figure 12) at its maximum position, when the elbows have rotated as far as possible toward the shoulders. From my film studies I have found this to be the final position of nearly every bench presser who MISSES a lift. This also happens to occur at the (guess where) sticking point. What's really funny about this is that any hope of pushing the bar through the sticking point is dashed when the arms rotate to this position. Since the hands can't move outward along the bar, there is little the triceps can do here in extension. Also, the anterior deltoid is largely ineffective by this point, and the pectoralis major is also not at the greatest leverage here either. It would be better to rotate in the other direction (elbows more towards sides) to at least put the arm in a position where the tricep could help more.
This brings up an interesting point, that rotating the arms here is a very crucial timing skill. The narrower your grip also the more critical it is since a narrower grip shortens the pectoralis major and thus makes it less of a contributor to bench press force production (since the shorter a muscle the less force it can generate). Ever notice that the narrow grip bench press specialists have tremendous trouble locking out at the top? With this grip, once they rotate themselves out (as in Figure 12) there is even less help possible from the chest to lock the lift out. I have seen this in Kazmaier and others, and we also showed it in my narrow grip style lift in our three-dimensional study (reference 6, section 1.4). The triceps kill you once you rotate out. Narrow grip benchers and probably ALL bench pressers need to avoid this maximm rotation position until the lift's completion. It will be fun to explore this further and somday show how this rotation should be performed optimally in the bench press.
2.10 - Torques About the Shoulder
A torque (or moment) is a measure of the effect of a force to produce rotation, the "turning effect" of a force, if you will. It is the product of the force multiplied by the perpendicular distance from that force to the point of rotation. An approximation of the total three-dimensional torque required at the shoulder during bench presses was obtained by calculating the moment of the force exerted on the bar about the shoulder (references 7 and 9, section 1.4) All torques calculated i this way are two-dimensional approximations of the net torque actually acting on the shoulders .These torques are due to the total force provided by the lifter (i.e., both arms are included). This is felt to be a good approximation of the total torque about the shoulder, since our three-dimensional data showed this was by far the largest component of the total torque.
Despite the enormous difference in the forces applied to the bar by the light experts versus the novice bench pressers (reference 7, section 1.4), the shoulder torques (whether normalized or not) required by the two bar paths showed no significant differences at any of the characteristic instants (see, for example, Figure 11). In fact, at the sticking point the torque required by the novice lifters was actually less than that required by the light expert lifters was actually less than that required by the novice lifters (see Table 8). Torque requirements were typically of the magnitude of 200 NM for the light experts and novices, as shown in Table 8.
The light experts' path has allowed them to lift 79% more weight without increasing the torque at the shoulder their musculature is required to generate. The large horizontal component of the bar motion as it leaves the chest moves the bar considerably closer to the shoulder when the sticking point is reached. The torque required to prevent the force decrease associated with the sticking point is reduced to a level attainable even in this "worst" configuration. Although the change in bar path may place the muscles crossing the shoulder joint in a position of reduced mechanical advantage, the drastic reduction in torque required would seem to more than compensate. In light of the moment it can produce at a joint or joints, as shown here it is probable that differences in kinematics play a significant role in determining differences in performance between groups.
When heavier expert subjects were later analyzed (reference 9, section 1.4), it was discovered that the torques produced at the shoulder were larger than for the light experts and novices. A look at Table 8 shows that at all positions evaluated they are about twice as large as the the values reported for the two lighter groups. The heavier group did lift 30% more weight and had upper body lengths 9% larger than the light experts (.508 meters versus .466 meters). If geometrically and temporally identical identical bench press techniques were used by all groups, then an increase in torque of 42% would be expected for the heavier lifters. Obviously, a much greater increase occurred. For some unknown reason the larger lifters positioned the bar farther away from their shoulder, relative to their upper body size, than did the smaller lifters. What may explain this unexpectedly great increase is the restriction in grip spacing to a maximum of 32 inches, which may prevent the larger lifters from maintaining geometric similarity with the smaller lifters. With a narrower (relative to their body size) grip the larger lifters are faced with a choice of either increasing moment at the elbow by increasing elbow flexion or of increasing increasing shoulder torque by moving the bar path horizontally away from the shoulder. Apparently, most large lifters choose the second alternative. This leads to the intriguing situation that while the weight lifted does not increase as fast as the body weight, the shoulder torque, which determines the muscle loading, increases faster than body weight. It may be that the heavier lifter is trying to copy the technique of the smaller lifter as much as possible within the grip width limitations of the rules of powerlifting.
Probably the most critical result from the analysis of the heavier lifters is that torques about the shoulder can be expected to be greater for bigger athletes during bench pressing. There is a logical link here supportive of the need for possible additional training of the shoulder and tricep musculature, or greater emphasis on beneficial techniques (horizontal bar path position, etc.) discussed previously. For larger athletes, both of these would appear important to help them handle the larger shoulder torques. Specialized training and technique work is thus probably more important the larger you are.
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