The work Accomplished by Muscles.—For practical uses this should be expressed in kilogrammeters. In order to reckon the amount of work which a muscle can perform under the most favorable conditions it is necessary to know (1) its physiological cross-section (2) the maximum shortening, and (3) the position of the joint when the latter is obtained.
Work = lifted weight x height through which the weight is lifted; or
Work = tension x distance; tension = physiological cross-section x absolute muscle strength.
If a muscle has a physiological cross-section of 5 sq. cm. its tension strength = 5 x 10 or 50 kg. If it shortens 5 cm. the work = 50 x .05 = 2.5 kilogrammeters. If one determines then the physiological cross-section and multiplies the absolute muscle strength, 10 kg. by this, the amount of tension is easily obtained. Then one must determine only the amount of shortening of the muscle for any particular position of the joint in order to determine the amount of work the muscle can do, since work = tension x distance.
The tension of a muscle is, however, not constant during the course of contraction but is continually decreasing during contraction. It is at a maximum at the beginning and gradually decreases
La tension décroit avec la contraction c'est bien ce que j'ai pu lire dans les autres textes, la tension est maximum à Lo (longueur maximum) + 0-5%.
Pour ceux qui aiment les math et la physique, plus d'infos ici :
Moi ca me dépasse... si DX ou Ablan se penchait la dessus peutêtre qu'il y a des trucs sympa, surtout à 366-8.
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amusant, ARTHUR JONES en parlait deja et à l'époque ca n'avait pas retenu mon attention... Mais sachant cela, je m'étonne qu'Arthur aie encore pu penser que c'est l'effort qui engendre the growth et non la production de force, soit la tension...
Numerous writers have mentioned the relationship of the size of a muscle to its existing level of strength; but they usually do so in a fashion that leaves a great deal to be desired at the very least, in a fashion that leaves the average reader in a state of total confusion, not knowing just what was meant -- some writers will state that there is a direct relationship between the "area of the cross-section of a muscle" and existing strength -- other writers put it differently, by comparing the "diameter of the cross-section of a muscle" and existing strength -- but regardless of how it is worded, it still means the same thing, the SIZE of a muscle indicates the STRENGTH of a muscle, and vice versa.
Now, for the benefit of those people who might wish to dispute my above statement on technical grounds, I will point out the fact that a muscle changes its LENGTH very little if at all as a result of growth; so we are NOT dealing with an ever-increasing sphere -- instead, for all practical purposes, we are dealing with a cylinder of constant length, and thus, if we double the area of the cross-section we will simultaneously double the mass, and if we increase the diameter of the cross-section of a muscle by a factor of approximately 1.4 (one and four tenths) then we will double the area of the cross-section, and also double the mass, AND ALSO DOUBLE THE POWER POTENTIAL of the muscle -- as least insofar as the "input" of power is concerned, although the lowered efficiency resulting from unavoidable changes in the "angle of pull" may not (probably will not) permit a doubling of measurable power, or power "output".
Because of such ambiguous wording -- such unclear statements in situations where clear expression is not only possible but highly desirable, even an absolute requirement -- most current weight-trainees remain totally; unaware of the simple fact that the size of a muscle is directly related to its strength; and since most bodybuilders are interested only in "size" -- and since they remain unaware that size is impossible without strength, and vice versa -- they ignore the only type of training that is capable of giving them the size they are seeking, strength training. And competitive weight-lifters are just as confused -- not realizing that increasing their muscular size will also increase their strength, MUST increase their strength.
plus de 3.5 ans d'entrainement et après avoir lu Jones 10'000x je suis seulement au courant de ceci depuis 1.5-2 ans, la honte en plus c'est tout con quand on pense à un cable, un os, n'importe quoi....
Comme le disait Ron Sowers :
La facon dont vous vous entrainez n'a pas d'importance tant que cela permet une progression en force, puisque la force d'un muscle est proportionelle à sa section.
Bien sur, quelqu'un qui s'entraine en série de 100, et qui progresse peu à peu, est bien loin de l'entrainement idéal car il s'entraine en force-endurance, des séries de 10 répétitions seraient bien supérieures. C'est en suivant cette logique que j'en ai conclu que rien ne pouvait etre supérieur à des singles, car les singles c'est pas de l'endurance, mais de la PURE FORCE, la contraction maximum.
Combien de singles ? quelles résistance ? On peut partir du maximum, soit 100%, soit son 1RM et faire quelques reps. Eventuellement, si la stimulation n'est pas suffisante (ca serait vraiment très étonnant), on peut diminuer l'intensité de 100% à 90-95% pour faire quelques reps additionelles. De plus, le principe SAID conforte cette idée, pour progresser en force absolue (et donc en muscle), il faut s'entrainer pour la force absolue, maximum, PAS en endurance.