Monday, August 23, 2010

Bench Press, Part Nine

Chris Confessore



2.18 – Relationship of Bench Press Capacity to Weight

The quest for relationships between bodyweight and muscular work is an old one. The argument that has been used is the past for relating weightlifting ability to bodyweight is the assumption that the lifting ability of a trained athlete is proportional to the muscle cross-sectional areas participating in the lifting. If ‘d’ is a typical cross-sectional dimension of the body such that muscle cross-sectional areas are proportional to d*d, then lifting ability is proportional to d*d, or :

Lift ~d*d

Since one’s bodyweight is proportional to volume (or d*d*d) then the lift is proportional to the bodyweight in the power law relation of the form:

Lift~(bodyweight)²

Where a/~ is the exponent of the power law relation and equals (2/3). Therefore, by this line of thinking a person’s lift should be proportional to their bodyweight raised to the 2/3 power, or:

Lift~W⅔

If this is true then man’s lifting capacity in weightlifting competitions should show this relationship. In 1956, Lietzke (reference 1) found that a plot of the 1956 world record totals in the classic found that a plot of the 1956 world record totals in the classic Olympic lifts (3 lifts) versus bodyweight was indeed linear on a log-log plot with a slope of approximately (2/3), hence confirming this power law relationship.

Lietzke suggested that in the future weightlifting totals would probably increase, but the slope of the line drawn through the points of weightlifting totals versus bodyweight (plotted on log-log paper) should continue to be approximately (2/3). It was Lietzke’s results that motivated me to investigate the applicability of power relations to different lifts, especially powerlifts like the bench press, to see if these arguments were applicable to such different lifts.

Analysis (reference 2) of the relationship of (3 lift) Olympic lift totals from 1952 to 1972 (using Olympic records) found that this relationship did still hold, with the exponents in the power law still equal to (2/3). Probably this increased relationship between bodyweight and lifting capacity for the current (2 lift) Olympic lifts has to do with the greater proportion of muscle mass participating in the two remaining lifts. The stats show an even greater relationship exists between bodyweight and powerlifting ability (reference 2).

A look individually at the three powerlifts (and totals) was next undertaken. It was quite interesting that in order of ranking, THE BENCH PRESS WAS MOST RELATED TO BODYWEIGHT, followed closely be the squat and then the deadlift (which was only related by an exponent (a) of about .86). What this helps explain is why many of us who bench press have noticed a loss in benching strength with even small decreases in our bodyweight. A loss of bodyweight thus typically will affect bench pressing poundages more than, let’s say, it will limit your ability to do the same deadlift maximum. Or conversely, this also explains why a gain in bodyweight typically seems to help increase your bench press (as well as squat) more than it affects deadlift poundages. This knowledge can be helpful to powerlifters or athletes who lose or gain great amounts of bodyweight quickly, in terms of rough selection of the proper weights use in the three powerlifts after experiencing the bodyweight change.

Further work on the relationship between the bench press and other powerlifts could lead not only to being able to predict future records, but also possible in generating a more valid and equitable method for determining the best lifter pound-for-pound in Olympic lifting or Powerlifting than current methods (Hoffman, Schwartz, Malone, etc. Formulas). In any case, if your bench press goes down, you at least now have another excuse (and you can claim it’s due to a loss in bodyweight)!


References

(1) Lietzke, M.H. “Relation between weightlifting totals and bodyweight”, Science, 124:486, 1956.
(2) McLaughlin, T.M. and Lardner, T.J. “The theoretical relationship between bodyweight and man’s lifting capacity”, research paper in preparation, 1984.


2.19 – The Importance of Chest Size

If you look at the physiques of most champion bench pressers, they typically have either a huge chest, short arms, or usually both. With a fixed arm length and grip spacing, the higher your chest is above the bench the less mechanical work you have to do. Work as defined here is the product of the force acting on the bar and the displacement of the bar in the direction of the applied force, which roughly is vertically upward in bench pressing. If you put some towels or rubber pads on top of your chest during bench pressing you will see that with the same grip spacing on the bar you can probably lift more weight. Consequently, developing the size of your chest is important to bench press performance and a reason why the bench press was shown to be so highly related to bodyweight (in the last Section, 2.18). It appears helpful to develop and maintain chest muscle mass to get and keep a big bench press. In fact, if you lose a lot of bodyweight and, let’s say, the height of your chest is reduced by even 1/4 of an inch – then the mechanical work you have to do will increase.

What’s interesting also is that letting your chest size diminish causes the bar to go down lower than normal (an extreme case would be to even allow sinking of the bar into your chest). When this occurs the key muscles involved in the bench press at the bottom (in particular the pectoralis major and triceps see 3.1) must work at muscle lengths they are not typically accustomed to. Consequently, the maximum force you can generate may be reduced.
Years ago, the great world champion bench presser and powerlifter, Larry Pacifico, visited the National Strength Research Center and in a workout showed me his version of getting the body optimally positioned for the bench press. Basically, the idea involves positioning the body to get the chest as high above the bench as possible. This is exactly what you need to do to reduce mechanical work and hopefully push up more weight in your bench press. It also makes sense, from a work perspective, to avoid letting the bar sink into your chest. Finally, as I mentioned in Section 2.8, a wide grip will also help reduce the mechanical work you have to do.

When I’ve taught weight training classes to novices I’ve always noted that the long-armed and small-chested “basketball” physique types had problems in bench pressing much weight compared to more amenable body types (larger chests, shorter arms lengths). Although obvious, keep this in mind. If I were of the long-armed and small-chested body type I would:
(1) work hard to increase muscle mass of my chest;
(2) use the widest permissible grip spacing;
(3) position myself to get the chest as high as possible off the bench; and
(4) not permit the bar to sink in at chest impact.

In fact, all of us need to follow these suggestions to help optimize our bench press.

No comments:

Blog Archive