question about the biomechanics of the press

[nazgulnarsil]

I asserted that the strict press was superior to the push press for shoulder activation and it sort of snowballed.

I was under the impression that a muscle generates the greatest force from a position of being stretched. So for example the pecs provide greatest force at the bottom of a benchpress, the anterior delts the greatest at the bottom of the press.

Wikipedia on the biomechanics of the military press: "The deltoid muscle has a dynamic activation to about 90–120 degrees of abduction. After that it has an almost static function the rest of the lift. The rest of the movement is mainly due to contraction of Trapezius muscle pars acendens, Serratus anterior muscle and trapezius pars decendens. They work together to tilt the Scapula to a position that make the glenoid cavity point superiorly enabling the last degrees of abduction of the shoulder."

Which indicates to me that the deltoid activation is isotonic in the first half of the lift and isometric in the second half, with the triceps providing most of the force in the second half of the lift.

Now this paper: http://www.ncbi.nlm.nih.gov/pubmed/2779404

says: "electromyograms produced by the prime mover muscles (sternal portion of pectoralis major, anterior deltoid, long head of triceps brachii) achieved maximal activation at the commencement of the ascent phase of the lift and maintained this level essentially unchanged throughout the upward movement of the bar."

And I don't know enough about how EMG readings related to isometric and isotonic contraction to really settle the issue. I had always assumed that the sticking point in benching was at the point of "handoff" between the pecs and the triceps.

My assumption WRT to the press was that the push press, by using momentum to get out of the bottom of the lift easier, is essentially skipping over the part of the lift that has the greatest deltoid activation. Is this true? My opponent countered that if such was the case we would all be doing partial reps for maximum gains, to which I pointed out arnold presses. At this point though I'm not sure what to think.

Any input would be most appreciated.

[Mark Rippetoe]

I think your conclusions -- "the strict press was superior to the push press for shoulder activation" / "a muscle generates the greatest force from a position of being stretched" -- are correct. I don't really pay any attention to/assign any value to EMG studies, since many of them have shown that the hamstrings are not involved in the squat. This assertion -- "the deltoid activation is isotonic in the first half of the lift and isometric in the second half, with the triceps providing most of the force in the second half of the lift." -- is probably correct. This -- "the push press, by using momentum to get out of the bottom of the lift easier, is essentially skipping over the part of the lift that has the greatest deltoid activation" -- is certainly true. Partial reps do not yield maximum gains because the whole ROM is not trained, and deltoids are obviously not the only muscle group in the movement. This -- "if such was the case we would all be doing partial reps for maximum gains" -- sounds like bodybuilder talk, gains being equal to mass improvement for his favorite muscle group.

But really, I don't think I understand your question.

[Eyzteinn]

We learned at school that a muscle is neither strongest when it it stretched the most, nor when it is shortest.

Also, I seem to recall that (some?) muscles, or, more precicesly, the muscle tendon, (can) store tensile force; for instance, running, you'll "save" some energy in the gasctocnemius when your foot hits the ground, which may be used when your foot leaves the ground. I guess the same logic can be applied to the bottom (chest) position of the (overhead) press?

And pr your quotation "The deltoid muscle has a dynamic activation to about 90–120 degrees of abduction."; unless my English grammar is completely fucked up, doesn't that mean it has it's greateast strength from 0 to 90-120 degrees? At which point it becomes a static muscle, contracting isometrically, to help stabilize the scapula/glenoid cavity/arm?

[Mark Rippetoe]

Might I also suggest that there is as much if not more shoulder flexion as there is abduction during the press?

Yes, there would be using our correct technique, since elbows are anteriorly positioned.

We learned at school that a muscle is neither strongest when it it stretched the most, nor when it is shortest.

That is probably true of a fusiform muscle much more than the deltoid. More sarcomeric overlap would result in better contractility, but my impression is that the delts never really stretch out in the start position of the press.

Also, I seem to recall that (some?) muscles, or, more precicesly, the muscle tendon, (can) store tensile force; for instance, running, you'll "save" some energy in the gasctocnemius when your foot hits the ground, which may be used when your foot leaves the ground. I guess the same logic can be applied to the bottom (chest) position of the (overhead) press?

This would require a rebound off the bottom. We're coaching the press now from a dead stop so we can involve the hips more in the drive up.

And pr your quotation "The deltoid muscle has a dynamic activation to about 90–120 degrees of abduction."; unless my English grammar is completely fucked up, doesn't that mean it has it's greateast strength from 0 to 90-120 degrees? At which point it becomes a static muscle, contracting isometrically, to help stabilize the scapula/glenoid cavity/arm?

I don't know how this could be precisely measured.

[hbriem]

I have a somewhat distantly related question that I thought I'd ask here instead of starting a new thread.

A friend of mine, a rather strong presser, has been doing press lockouts with ~10% over his press 1RM.

I myself, have trouble locking out even my mediocre 77.5kg press, yet I have no trouble locking out a 135kg bench press and I've even done 160kg shirted bench and 170kg bench lockouts.

Now, supposedly the lockout in both lifts is all tricep, while the start involves the pecs (and ant. delts) in the bench and the traps and lat. delts in the press.

So if both lockouts are "the same" why is the press lockout much, much harder (about twice as hard in my case)? I'm just wondering about this, the answer isn't important as such. One does what one can.

[Mark Rippetoe]

The lockout in the press is traps and triceps, and this is radically different than in the bench. The last part of the press lockout is a trap shrug that rotates the scapulas medially and superiorly, and this is why no impingement occurs in this position. Triceps lock out the elbows and traps support the load overhead. In the bench, the scapulas are pinned together against the bench in a retracted position and do not move at all -- shouldn't anyway.