Flexor's Guide - Effects of bench press grip width on fibre contraction and damage

[Flexor]

Recently I've been thinking of chest development and I thought I would share a few of my thoughts based on the research I have done. I wrote this mostly from study memory but I did consult with a few references and hopefully it will give you a little more insight into your chest workout. This isn't an official article, but I think you will agree that I have done my research. Bare with me as I explain, it will become more obvious towards the end

Effects of muscle fibre shortening on fibre damage

When a muscle fibre shortens, the myosin cross bridges involved with binding to the actin within the fibres, becomes disrupted. This reduces the strength of the muscular contraction as the fibres shorten beyond their 'sticking point'. The sticking point is where the muscle fibres shorten to a specific point where maximum force can be produced, but this will not mean maximum force is produced mechanically because leverages will vary. Anyway, as the fibres go past this sticking point as it is called, tension decreases across the length of the fibre and if tension decreases, force is reduced and less damage can be done to the fibres.

Effects of muscle fibre lengthening on muscle damage

When a muscle fibre lengthens under contraction, or in other words it contracts eccentrically or negatively, the situation is different. The greater the stretch in the muscle fibres, the greater the tension developed and therefore more force can be produced leading to increased levels of fibre damage.

These principles applied to chest development

If you bench press with a narrower (i'm not talking close grip here, rather a medium grip) rather than wider grip, you are getting more or less the same fibre recruitment (Clemons & Aaron. 1997. Effect of grip width on the myoelectric activity of the prime movers in the bench press. J. Strength Conditioning). However, the wider grip allows a greater stretch in the fibres at the bottom of the rep which means more force can be developed (Hall. 1995. Basic biomechanics. Mosby). The fibres also contract horizontally in the direction that they run across the chest, which creates maximal levels of force in the fibres by removing the angular element of the contraction (mechanics in a straight line is always superior to angular mechanics).

If you think about how much the fibres contract though, obviously with a wider grip you have a lower range of motion at the top of the movement because of hand spacing, which does limit fibre shortening. This effect is conteracted though, by the greater stretch at the bottom of the rep. Consequently, between a narrower and wider grip there is probably a similar level of overall fibre contraction. Contraction however is just a general term, because the wider grip will be allowing a greater stretch and the narrower grip allows more shortening at the top of the press.

To conclude, the greater stretch of the wider grip will increase force production and therefore damage, whereas the narrower grip will develop both less force because of no stretch and also because of maximum fibre contraction at the top of the press (due to interference of the myosin cross bridges and a reduction in tension). This makes the wider grip better for force development and damage, but will increase the chance of shoulder damage.

Differential non-uniform, localised fibre contraction

It must also be considered that the fibres will stretch more in the outer regions of the pectorals because they are stretched over the sides of the ribs. The inner portions of the fibres will stretch horizontally and therefore less overall. Hence, the wider grip will develop more force in the outer regions at the stretch and these will ache more due to greater damage (numerous people will have felt this). The narrower grip will theoretically develop your chest more equally but slower at the outer chest, and the wider grip will develop the outer chest before the inner. Eventually though, overall development of the chest as a whole will bring the inner pec out just fine as the outer chest becomes limited by genetics and the inner chest is still to fully reach its potential.

I used to believe that it was a myth that the fibres were recruited differently in the inner and outer chest. Now I know it is no longer a myth, if you are doing a wide grip. Does anyone have any thoughts on this subject, I would appreciate them because it took some time to write this, it was fun though...

And yes, I did write this, it is not a rip off in any way

[24labor]

good post flexor I always like to read how things work scientifically and such

[24labor]

I used to do wider grip myself but I havent in a while I do more of the traditional narrower grip. I'd have to so when I did wider grip I was more sore than my normal set

[S.P.G]

Exultant post flexor, well explained to, the sliding filaments theory isn’t the easiest thing to get your head around, I think your research is coming along nicely....

What exact grip, in trams of wildness would you recommend? just past shoulders width?

what do you think is to wide?

I no it can be potentially dangers to go to wide, the acromioclavicular joint is vulnerable to injury in collision with heavy wide bench press along with overhead motions.

Do you think the same recruitment and behavior will apply for other muscle groups?

again good post bud

[Flexor]

Exultant post flexor, well explained to, the sliding filaments theory isn’t the easiest thing to get your head around, I think your research is coming along nicely....

What exact grip, in trams of wildness would you recommend? just past shoulders width?

what do you think is to wide?

I no it can be potentially dangers to go to wide, the acromioclavicular joint is vulnerable to injury in collision with heavy wide bench press along with overhead motions.

Do you think the same recruitment and behavior will apply for other muscle groups?

again good post bud

The best way to think of sliding filament theory is as a ratchet mecanism, like a zip on a jacket. That is how I have always heard it explained in a simpler way.

I would personally recommend just wider than shoulder width, allowing the elbows to flare out slightly from the body. Not tucked in, but not far out. I think too wide is probably when your lower arms are vertical at the bottom of the rep with the bar across the chest and when the elbows are seriously far behind the back so that you have a full posterior delt contraction.

Yeah the AC joint is what gives me problems when I do flyes, because the upper arms are flared out so much. I have always bench pressed with a medium grip until the last three months because I wanted to accelerate my chest growth. It did that, but I've returned to a medium grip and I prefer the overall feel and the increased shoulder recruitment. That way less overhead presses are required for my front dels, as my shoulders really don't like them much either.

I think this type of behavior will apply to any muscle group that can be stretched at the bottom of the rep. E.g. incline dumbell curls will stretch the bicep at the bottom and increase force and damage. However, I think the very specific behaviour of the localised areas of stretch in the bench press only applies to the traps and no other muscle. The top trap fibres are recuited differently to the mid fibres, and differently to the lower fibres even though there are common insertions. The long head of the triceps can be stretched with overhead presses, but I believe there is a uniform stretch throughout the head, unlike the traps or pecs. This kind of localised stretching will only occur in muscles with huge areas, perhaps the glutes or lats as well.

The stretch of course does not meant the fibres are recruited any differently, its just that it causes more damage because of increased tension. Thanks for your input SPG.

What grip do you currently use and how do you feel about its various merits etc?

[*Narkissos*]

I like your approach Flex...and despite what you think... you HAVE written an article.

[*Narkissos*]

The greater the stretch in the muscle fibres, the greater the tension developed and therefore more force can be produced leading to increased levels of fibre damage.

I think this is a self-limiting hypothesis. Yes...the above-mentioned is true..but there exist more variables than just width as a determinant of stretch..and, consequently, a gauge of tension.

I think the narrower (i.e. shoulder width) grip has a greater range-of-motion. An increase in R.O.M. is equal to an increase in distance travelled...which in turn is increases time under tension. Increased time under tension will result in greater muscle damage. Correct?

Your theory does not investigate arm placement (i.e. elbow allignment) in regard to stretch... Elbow allignment is an important determinant. e.g. Flared elbows increase the stretch...do you see where i'm going with this?

[*Narkissos*]

Differential non-uniform, localised fibre contraction

It must also be considered that the fibres will stretch more in the outer regions of the pectorals because they are stretched over the sides of the ribs. The inner portions of the fibres will stretch horizontally and therefore less overall. Hence, the wider grip will develop more force in the outer regions at the stretch and these will ache more due to greater damage (numerous people will have felt this). The narrower grip will theoretically develop your chest more equally but slower at the outer chest, and the wider grip will develop the outer chest before the inner. Eventually though, overall development of the chest as a whole will bring the inner pec out just fine as the outer chest becomes limited by genetics and the inner chest is still to fully reach its potential

I think localised development is a myth.

The body is not an asymmetrical mechanism. Indeed, experiences point to the contrary.

e.g. If you're doing a barbell bicep curl and are consciouly contracting only one arm...BOTH arms will grow. I won't delve deeply into this thoery... but here's a study done on stroke victims. It illustrates that when motor function was lost in one arm, the most effectice recovery protocol was bilateral work...as opposed to unilateral work: http://www.clinicaltrials.gov/ct/gui/show/NCT00108680

This strays some from the point, as it is not the study i was trying to find, but it illustrates that the body is not an asymmetrical machine... thus i believe your hypothesis, regarding to the wide grip activating the outer fibers to a greater degree being a determinant of growth, is flawed.

Sorry i couldn't be more indepth. I've got an exam in the morning i'm here trying to study for.

I loved your approach by the way.

Tweak it... and you've got and article.

~Nark: Awaiting more.

[Flexor]

Hey Nark, thanks for the post.

Yes I had not considered the TUT in relation to the increased range of motion, thanks for the point. I have heard TUT is even more important than the range of motion, so if reps are done slowly and through a full ROM surely these would be the best.

I deliberately left out elbow alignment because I didn't want to overcomplicate the ideas I was trying to make, but again, very good point. A narrower grip will automatically bring the elbows in, and I covered this somewhat when I said about the contraction of the fibres at an angle, rather than at a straight line.

With regards to the outer fibres, I said that there may be a greater stretch there, not greater activation. The stretch will therefore cause more damage in the outer fibres and then more growth. I know that the activation of motor units is uniform across the muscle, but I wasn't sure about whether the stretch was uniform. The only reason I believe the stretch may be non-uniform in the pecs and no other muscle, is because the elbows go behind the back and it seems as if the outer fibres are stretched more. Maybe an elastic band would help to find out. What is your view on this? Maybe when you have time away from studying you could post...

Thanks for your input, you are making me reconsider my ideas and that is always a good thing