I just finished the book, Static Contraction Training by Peter Sisco and John Little (BTW - every book I have read of theirs has been awesome). The book is a very good read above and beyond teaching the fundamentals of SCT! I thought this was an excellent way to describe muscle contractions:
Muscle contraction begins with an electrical signal from the central nervous system. When the current arrives at the muscle, it is immediatly transferred up and down the length and depth of the muscle through a relay system of tubules. When the message reaches each one of those thousands of receptor sites, it drops of a little shot of calcium. Calcium inhibits the noncontractile proteins tropin and tropomyosin, which, until calcium showed up, had been doing there job of keeping the actin and myosin proteins seperated. The calcium has the same effect on tropin and tropomyosin that kryptonite has on Superman - it takes away their power to seperate actin and myosin, inhibiting their ability to function - and their function, of course, is to keep the contractile proteins from contracting.
Further analysis reveals this process even more clearly when we look at the sarcomere, which is simply one individual unit of actin and myosin. At each end of the sacromere is a rather broad anchoring structure called a z-disc. And extending inward from each z-disc are thin strands of actin that just manage to overlap the much thicker strands of myosin that reside smack-dab in the middle of each sacromere.
Myosin protein strands have little receptor site that emanate outward from either side of their main bodies that resemble something of a cross between little hooks and the strands of a feather. Technically, these receptor sites are called cross-bridges, as they serve to bridge or connect actin and myosin.
Once the electrical charge for contraction arrives via the nerve cells from the brainto the muscle, the nerve cells drop off a little packet of calcium that immediatly severs the leashlike effect of the troponin and tropomyosin. With the leash removed, so to speak, several rather phenomenal actions take place involving the now free-floating actin and myosin:
When many of these sacromeres shorten simultaneously, the muscle fibers - and then the muscle itself - contract. And, although some textbooks may tell you that the shortening of the sacromere is caused by the release of energy caused by the breakdon of ATP (adenosine triphosphate), this is not the case. In fact, the process of contraction will occur automatically whenever calcium enters the picture, thus inhibiting the restrictive function of the troponin and tropomyosin proteins. ATP is required, however, for the cross bridges to release and return to their "resting" position until their required to contract again. An example of this can be seen if you flex the biceps of in your upper arm. This is the result of thousands of contractions and (if you extend your forearm) releases by the cross bridges, with the contracting portion precipitated by the presence of calcium and the release fueled by the energy generated by the breakdown of ATP.
- The cross bridges rotate and in so doing draw the actin filaments and z-discs inward ever so slightly.
- The cross bridges begin to attach to the actin protein strands.
- The proteins themselves undergo a change in shape.
- The sacromere shortens as both z-discs are drawn inward.
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Maybe if I muster up the typing skills one more time all post that as well... pretty informative on hat sup manufacturers can say, can't say and hat they do say... otherwise get the book...
Originally Posted by Warrior
) - as you probably already know, there are three types of muscular failure... 1) concentric failure - simply means you can't lift the weight again. 2) static failure - your muscles are so wiped out that you can't even hold the weight statically at any point in the range of motion. 3) eccentric failure - this the point where you can't control the weight as you lower it, regardless of what tempo you're using. Going to static failure places a greater demand on your body (a greater training stimulis), rather than simply stopping when you can't push or pull anymore. Here is part of their argument... the authors of SCT say negatives are not as good as static holds because there really is no way to judge improvements (training progression) - you don't know how much force you are exerting per workout. For example - when doing slow negatives you may be pushing 405lbs with anywhere between 315-400 pounds of force output... with static holds you are holding 405 - when you can't hold it anymore the set is terminated. You know where to measure improvements for next time.
