Tuesday, August 10, 2010

Bench Press, Part Seven





2.11 – Changes Over Time in Top Bench Pressers

I first began taking high-speed films of Senior National and World Championship powerlifting meets ten years ago at the 1974 Senior Nationals (with the generous help of John Pettitt), and over the past decade I’ve been able to collect cinematographic records (using Estar-AH film, which is archival) of many top lifters at different points during their careers. Some lifters, like Mike Bridges, I’ve been able to film every year over five years.

I’ve recorded a number of other top lifters as they have also moved through several weight classes (usually up!) over their careers. Although I am still waiting for the sample of lifters I have over time to increase, there are some interesting trends I have noticed in the results I have to date (unpublished data). High-skilled bench pressers who increase their over time do typically change their bar path significantly over the years. For example, the horizontal position of the bar path is displaced more toward the shoulder and in particular the angles 3 (circled) and 4 (circled) especially (see Figure 11) decrease significantly. Their bar acceleration data also follows the trend to reduce over time as discussed in Section 2.2. Related to the bar acceleration data, the force application to the bar at the sticking point typically increases dramatically over time, even though there is not significantly more force exerted off the chest. As discussed in Section 2.4, it seems that over time the high-skilled bench pressers preferentially get stronger at their weakest (or sticking) point more than they get stronger at their strongest point off the chest. They develop this improved performance at the sticking point certainly by better technique (as we have documented) and possibly by specialized training.

I have seen, for example, lifters like Bridges work the sticking point region using paused singles with overload poundages at a position only a few inches above the chest (remember Figure 8, Section 2.5!). Whether technique or specialized training is the cause, it is clear that these skilled lifters’ capacity at the sticking point increases over time.

Figure 13 typifies the changes that occur over time in the better bench pressers. Note in this figure that the solid line (which represents Bridges’ vertical bar acceleration during his 446 lb. world record bench press in 1979) is much flatter than the dotted line denoting a 386 lb. attempt a year earlier. The most important thing to note here is how much more positive the bar’s vertical acceleration is at the sticking points of these lifts (compare the positions of instant (7) in both curves of Figure 13). Newton’s laws indicate the Bridges’ was exerting considerably more force at his sticking point in his later lift in 1979. It can be seen also in Figure 13 that he took much more time to lower the bar (see difference in points of chest touch), which is another trend evident over time (as in Section 2.2, Table 3). I have documented similar changes in other top bench pressers over time besides Bridges, like Kazmaier, Gaugler, etc.

The real value of analyzing lifters’ performance over time is to document what changes in technique are associated with greater poundages lifted. Conversely, it can also work to help those not progressing in bench press poundage to identify what technique changes they need to make. For example, the lifters I have tracked over time who have not progressed significantly also did not have the technique changes typical of the successful lifters. One superheavyweight, the great P. Wrenn, had nearly the same technique each of the years I analyzed his performance using the same poundage of 524 pounds. Perhaps if he had made the technique changes we’ve discussed he could have pushed his lift up even beyond this respectable poundage.

It would certainly be valuable to analyze our top powerlifters every year, six months, etc. in order to help identify their technique development and suggest any needed changes. Perhaps between the Senior Nationals and the World Championships our U.S. team could be analyzed in this manner. The United States Olympic Committee funds this type of biomechanical analysis for most Olympic teams at their meets throughout the year. For example, the men and women track sprinters were analyzed at many top meets over the past three years prior to the Olympics, and biomechanical changes in their technique calculated and pointed out to their coaches. There’s no reason in the world why we can’t do the same for our lifters (at all levels). This is a good way to objectively diagnose the effects of different training programs over time. In any case, I will continue to collect films whenever possible in order to keep developing our database on bench press techniques.


2.12 – The “Pause” in Competition

In powerlifting competition, the lifter must “pause” at the chest during the bench press before pushing the bar up to completion (see Section 2.1). At this position the bar must be momentarily motionless as the lifter waits for a signal from the referee signaling that he may begin pushing the bar. Like any powerlifter, I have experienced quick pauses in competition as well as some that seem an eternity (you’re just sure the referee has gotten up and gone on a break!). On the average, the “pause” lasts about two seconds.

Although the major reasons for the pause in the competitive bench press are undoubtedly to insure consistent and fair judging of the lift and even to reduce potential injury from excessive bounces . . . it sure doesn’t help bench press poundages! As most powerlifters are well aware, a paused bench press is a lot harder to do than a “touch-and-go” or slightly bounded lift. Personally, it occurs to me that we could make the pause less devastating on bench press poundages, more consistent than possibly even the best judges, and make it more like the touch-and-go lift we all enjoy more . . . if technological changes are made in the pause signal procedures. I hope to present these at some point to the governing bodies of powerlifting.

But, why does the “pause” hurt bench press capacity? First of all, let’s examine the concept of “elastic energy”. Let’s look first at a scene where we have a powerlifter on a pogo stick bouncing along the road. Each time he lands on the road, energy is stored in the pogo stick’s spring and this energy is subsequently released during the elastic recoil as he takes off again. This suggests that in a similar manner energy might be saved if springs were somehow built into the human body. These springs which store the energy and release it again when required would allow our powerlifter to bounce along using much less power and this time without the pogo stick. Kangaroos, for example, are so good at this that they require less energy the faster they hop!

There is, in fact, evidence that a good deal of energy in human motion is saved by elastic structures in the body (used much like the spring in a pogo stick). One such study (reference 1) showed convincingly that energy is stored by elastic structures in human legs. The oxygen consumption of men was measured while they performed squats 20 times per minute. In some of these experiments the subjects “bounced” at the bottom of the squat and in others they stopped at the bottom for one second to avoid any rebound effect. On the average, the subjects used 21 to 27% less oxygen when using the slight rebound at the bottom of the squat! Apparently, the rebound saved a good bit of energy. Indeed, other studies verify this finding and show that a rebound at the bottom of a squat or vertical jump can increase the upward force applied by as much as 20 to 30% (reference 2, reference 3).

The mechanisms by which this phenomenon occurs has been studied more recently (reference 4, reference 5). It has been found that if a muscle is stressed (during an eccentric contraction – as when going down in a bench press), almost immediately before the muscle shortens (during the concentric contraction – when coming up in the bench press), then there will be more energy available to the upward motion. This means that there will be more weight lifted in the bench press. In other words, one needs a count movement followed almost immediately by the movement desired. Note that in terms of timing the eccentric phase must be followed very quickly by the concentric phase. Hence, a rebound at the bottom of the bench press is very helpful in getting more weight lifted.

It has also been found that the velocity of stretch of an active muscle (during, for example, the rebound or “bounce” at the bottom of the bench press) determines how much storage and utilization of this elastic energy actually takes place (reference 2, reference 3). There is an optimal amount of speed in this rebound (or “bounce”) at the bottom of the bench press that each powerlifter should use. Obviously, many factors (like bar momentum, the physical condition of the lifters, etc.) determine how much of a rebound load each individual powerlifter can beneficially tolerate in bench presses. This could possibly be determined for each lifter through biomechanics research.

In the research that I have done on the squat, I found that bar momentum must be controlled on the way down during the squat until perhaps a few inches or so above parallel. Typically after this point is reached, the top lifters then begin to increase the velocity of the descent before starting to drive up out of the bottom. Less skilled squatters were found to let bar momentum get out of control early in the squat and typically reach the bottom with higher rebound velocities (or “bounce” than the better squatters. It seems logical that less skilled or beginning lifters are less able to tolerate these greater rebounds than top lifters can! This is mainly because training has been found to help increase the ability to store and retrieve elastic energy. It has also been shown that males can usually handle greater rebound loads than females (reference 5).

Where is all this elastic energy stored? Since we don’t actually have springs embedded in our bodies (although one can’t always tell what the Soviets, the East Germans, etc. will do next), the energy must be stored somewhere in the body before being used later. This energy is stored in the body primarily in the tendons and to a lesser extent in the elastic components of the muscles themselves.

Now, my discussion so far has been about how elastic energy is stored briefly in the body by a counter movement before being retrieved to help the movement start. I have discussed the squat in particular, although this also explains why bench press repetitions are easier with either a bounce or touch-and-go than when paused. We lose virtually all the elastic energy during the second(s?) we are holding the bench press pause while waiting for the referee’s signal. From what we’ve seen so far, it does make sense for a lifter to try to “anticipate” the referee’s signal and try to minimize the time of his pause as much as possible. Biomechanically, letting the bar sink in briefly after a pause before pushing the bar up (or “heave” as it’s often called) doesn’t make much sense either, since:

1.) letting the bar sink into the chest increases mechanically the work necessary in the lift; and
2.) there is probably not much chance to “restore” significant levels of elastic energy to be of much help off the chest.
Rather, it seems better to keep the bar from sinking in and try to “anticipate” the end of the pause. It’s hard to tell whether as much elastic energy is stored during a bench press as in a squat, but I doubt it. Nevertheless, keeping the pause as short as possible will decidedly help the bench presser’s performance. Regarding training for the pause, it seems much safer to NOT use pauses extensively in bench press training. If done, the ability to store elastic energy will not be trained, and consequently it may end up that on a “shorter” pause in competition someday you’ll miss out on what could have possibly been a successful lift if “touch and go” style bench pressing was mainly done in training. It has been my personal experience that pause bench presses leave me “flat” (or feeling as if I’m without possible elastic energy storage ability!). However, I DO think techniquewise that “touch and go” pauses are smart to do prior to a bench press competition. I do not believe that excessively long pauses are valuable, whether it’s after a few seconds or an hour on the chest, the elastic energy transfer is lost anyway.


References

(1) Thys, Hl, Saraggina, T. and Margaria, R., Journal of Applied Physiology, 32, 491-494, 1972.
(2) Cavagna, G.A., Dusman, D. and Margaria, R., “Positive work done by previously stretched muscles”, Journal of Applied Physiology, 24, 21-32, 1968.
(3) Komi, T.D. “Neuromuscular performance: Factors influencing force and speed production”, Scandanavian Journal of Sports Science, 1, 2-15, 1979.
(4) Asmussen, E., and Bonde-Petersen, F., “Storage of elastic energy in skeletal muscle in man”, ACTA Physiologica Scandanavia, 91, 385-392, 1974.
(5) Komi, T.D., and Bosco, D., “Utilization of stored elastic energy in leg extensor muscles by men and women”, Medicine and Science in Sports, 10, 261-265, 1978.

No comments:

Blog Archive