Pre-Loading Muscles

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busupshot83

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On pg. 9 of the NSCA-CSCS Essentials textbook, the concept of pre-loading is presented: "[when] high tension is devloped in a muscle even before movement occurs... because the weight must be supported isometrically." By "isometrically," are they referring to "isometric muscle contractions?"

Still, I find the textbook's explanation to be unclear. Can someone explain the concept of pre-loading in their own words? Thanks.

bus
 
Preloading is based of the the fact that a muscle exerts more force
before the contraction. Often the best examples used to describe this is a jump.
You are going to squat (pre-loading your hamstrings, quads, etc) and then you will release that brief isometric hold into a forceful power driven jump. This is the storing of elastic energy, like a rubber band you are going to shoot at someone.
 
Leigh P said:
Preloading is based of the the fact that a muscle exerts more force
before the contraction. Often the best examples used to describe this is a jump.
You are going to squat (pre-loading your hamstrings, quads, etc) and then you will release that brief isometric hold into a forceful power driven jump. This is the storing of elastic energy, like a rubber band you are going to shoot at someone.
Click to expand...

Thanks for the description. Would doing dumbbell chest presses be considered pre-loading? The reason I state this is because prior to the contraction of the exercise, your muscles are under tension as they hold the dumbbells above your chest. In comparison, a machine press which utilizes hydraulic systems does not force you to hold the weight isometrically prior to the contraction, and therefore, is not considered pre-loading. If this is incorrect, can you please give me another example of pre-loading (I love examples)?
 
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busupshot83 said:
Thanks for the description. Would doing dumbbell chest presses be considered pre-loading? The reason I state this is because prior to the contraction of the exercise, your muscles are under tension as they hold the dumbbells above your chest. In comparison, a machine press which utilizes hydraulic systems does not force you to hold the weight isometrically prior to the contraction, and therefore, is not considered pre-loading. If this is incorrect, can you please give me another example of pre-loading (I love examples)?
Click to expand...

Preloading is most often used during explosive movements. The best example I can give for pre-loading is plyometrics. Specifically, the box jump. To perform a box jump, you must first bend at the knee, which places the utilized muscles in under tension, and then almost immediately you contract your muscles and explode out of you preset stance to jump on top of the box. The basis of preloading is that your muscles are able to produce the most power at about midway through their range of motion, based on tension-lengthening curve. Chest press really isn't an example of preloading. All the muscles involved at the begining of a chest press are lengthened fully, and the tension, to which you refer is more of a stabilizing effect. An example of a preloaded chest exercise would be the clap-push-ups, because you must move into a preloaded, bent arm position when you begin the exercise, and have to "catch" yourself, returning you to that preloaded position at the start of each rep.
 
I think the preloading they are referring to is best illustrated by a biceps curl. When the arm is completely straight you can completely relax your biceps so it is exerting no force. Then when you get ready to start the curling movement, you begin to flex your biceps, but the eblow joint does not begin to move yet. You can think of it as holding your arm motionless and trying to pull the tendon from the insertion point in the forearm. You should feel a kind of stretching feeling in the area where the tendon connects to the end of the biceps. Eventually you will generate enough force to allow the curling movement to begin.

There is some conjecture that that stretching feeling you feel is actually micro-abrasions being caused in the muscle which become the stimulus to muscle growth. So the theory is that by accentuating that feel you are enhancing the effectivenss of the exercise. The interesting thing is that if you watched 2 people doing a biceps curl you probably could not tell which one was doing that extra mental exercise to get that feel and which one was not.
 
illiniphase4 & dswithers:

That makes sense, thanks a lot!

bus
 
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