The form -- or "style of performance" -- required for producing good results from weight-training is a much talked about, but little understood, point of importance. The "amount of work performed" and-or the "power produced" will in most cases be the same regardless of the form used -- but at the point, similarities cease.
If, for example, you are doing curls with a barbell -- using 100 pounds for ten reps -- the amount of work performed will be the same regardless of how you perform the movements, and the amount of power produced will be the same if the "speed of movement" is the same; but if cheating methods are used, then it wonít be the bending muscles of the arms that are performing all the work -- or producing all of the power. You will, in that case, be working your lower back muscles, your shoulders, and even your legs -- and very little of the work will be done by the arm muscles, But the muscles you are trying to work; as a natural result, little or nothing in the way of arm development will result from any amount of exercise.
But the above is not meant to imply that "cheating" methods should never be used -- on the contrary, they; should be used, they should be used in almost every set, and in every exercise where they can be used to an advantage; but they should be used only at the end of a set, only when several repetitions have been performed in perfect form, only when it becomes absolutely necessary to cheat in order to continue, and you should cheat only to the degree necessary, cheat to make continued movement possible, not to make it easy.
In a curl, for example, the first six or seven repetitions should be performed in literally; perfect form -- with no body-swing, no heave, no leaning back under the weight at the end of the movement; the arms should raise the weight throughout the entire range of movement, with no assistance from other muscles. But if the selected weight is proper, it should become impossible to continue while maintaining perfect form after six or seven repetitions have been performed; if you can perform eight (or more) repetitions without cheating, then the weight is too light and should be increased for the next workout.
But, regardless of the number of repetitions you can perform in perfect form, donít stop at any particular number, and donít stop simply because cheating becomes necessary; instead, do as many repetitions in perfect form as you can -- and then do two or three more repetitions, which will require cheating. But cheat as little as possible, cheat the absolute minimum amount required -- if the weight swings up rapidly and flops into the top position, then you are doing nothing worthwhile, nothing of any value for the arms at least, simply burning up energy for no good purpose.
If you can perform only four or five repetitions without cheating, then the weight is too heavy -- and should be reduced; in most cases, try to select a weight that will permit seven reps in perfect form -- then do a total of ten reps, cheating only as much as absolutely necessary during only the last three reps. Or, if your "guide figure" (the number of repetitions you are trying for) is 15 reps, then use a weight that will permit about 12 reps in perfect form; in effect, use a weight that will permit 70 to 80 percent of the number of reps called for in the guide figure -- then cheat two or three extra reps.
And remember -- while it is necessary to produce maximum-possible power in order to stimulate growth, it is NOT necessary to do so while you are actually strongest, actually able to produce the "most" power; the same degree of muscle-growth stimulation will be produced if such maximum-power production occurs only near the end of a set of several repetitions, at a point where your actual power production may be quite low -- at a point where the earlier, non-maximum repetitions have weakened you momentarily.
Thus, while you could move quite fast during the first repetitions without cheating, restrict your actual speed of movement to a speed well below what you could do -- until at least the fourth repetition. In effect, the first three or four repetitions will move slower than necessary -- but after the fourth repetition, move the weight as fast as possible without cheating; which movement will be, in fact, quite slow. In this manner you will NOT be producing maximum possible power during the first three or four repetitions -- but you will be producing maximum possible power during the last several repetitions; and you will be GREATLY reducing the danger of injury. Also remember -- you are most likely to hurt yourself during a "first" repetition simply because you are strongest at that point; and so long as good form is maintained -- including properly performed cheating methods -- you become less likely to hurt yourself as you continue with the set, the second rep is less dangerous than the first rep, the third rep is less dangerous than the second rep, etc.
Although, of course, it is possible to hurt yourself in any rep; but in practice, most injuries occur during first reps -- and these injuries that occur during later reps are usually caused by using poor form.
It is not, however, necessary -- nor desirable -- to use an extremely slow speed of movement during the first few reps of a set; if, for example, you could curl a barbell in one-third of a second, then it is not necessary to restrict your speed to a point where the first rep takes two or three seconds -- instead, perform the movement at a speed where perhaps one second is required for the complete "upwards" movement.
Nor is it necessary to attempt to measure the time required; you can, rather easily, "feel" the required speed -- you will almost always know if you are actually moving as fast as possible, or not doing so.
Thus, during the first three or four repetitions, move at a speed that you "know" is below maximum possible speed -- below MOMENTARILY maximum possible speed. And during later repetitions, move at absolutely maximum possible speed -- but using good form, avoiding jerking; a speed that will be quite slow in fact.
For safety -- and for producing good progress -- form is one of the most important points; NEVER sacrifice form in an attempt to use more weight or perform more repetitions -- but ALWAYS use as much weight as you can, and ALWAYS perform as many repetitions as you can, in good form.