Take the 2-minute tour ×
Biology Stack Exchange is a question and answer site for biology researchers, academics, and students. It's 100% free, no registration required.

Just a random question, would a sharp object pierce your muscle more(stabbed with the same amount of force) when the muscle is flexed or when relaxed?

share|improve this question
    
I would say that it would depend largely on the muscle. –  Rory M Feb 28 '12 at 19:41
    
lets say any large muscle, abdominals, hamstrings, shoulder, etc @RoryM Edit: or are you talking about the muscle density? –  stackErr Feb 28 '12 at 19:44
    
Depends on the stabbing force and how sharp the object is. –  kmm Feb 28 '12 at 21:11
    
I suppose in theory the density of the tissue has increased during contraction if you stab in the middle so (preparing for a possible physics disaster) that would mean less penetration for constant force from an identical object –  Rory M Feb 28 '12 at 22:36
add comment

1 Answer

up vote 6 down vote accepted

Well, if we look in very basic detail at how muscle contraction works within a myofibril of the sarcomere:

Animation of muscle contractions

N.b. this isn't on a loop and only plays through seven times

The red lines represent actin filaments whilst the blue lines represent myosin filaments. During muscle contraction the filaments move over each other:

Relaxed myofibril

Partially Contracted myofibril

(Over)Contracted myofibril

As shown in the above diagrams the "more contracted" a muscle is then the smaller the size of the H zone (the area where there are just myosin filaments).

So if we consider a penetrating impact that went through a plethora of identically aligned sarcomeres (obviously this is not the case in nature) then we could presume that (et ceteris paribus) the object would not penetrate as deeply into a contracted muscle as it will hit more tissue on its route than in a relaxed muscle.

share|improve this answer
2  
Thanks for a very detailed and clearly explained answer! Pity i didnt take Bio during high school...interesting stuff –  stackErr Mar 25 '12 at 12:16
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.