Almost all conventional exercises are based upon resistance provided by gravity; but even when springs are used as a form of resistance, the result is much the same – such resistance is uni-directional. And while it is possible, with the use of pulleys, to control the direction of resistance -it still remains almost impossible to provide resistance in more than one direction while using conventional training equipment.

There are a few exercises involving conventional equipment that can be performed in such a manner that this limitation regarding the direction of resistance can be overcome – at least for all practical purposes; but since these exercises form the subject of a later chapter, I will ignore them for the moment.

This limitation in direction of resistance is probably the greatest limiting factor effecting most exercises; since it thus becomes impossible to build lean muscle fast and involve more than a small percentage of the total number of fibers contained in a particular muscular structure in any conventional exercise.

Because, while the resistance is provided in only one direction, the involved body parts are rotating; in effect, you are trying to oppose a rotational form of movement with a reciprocal form of resistance – an obvious impossibility. Impossible, at least, with conventional training equipment.

While performing a curl, for example, the movement is rotational throughout a range-of-movement of approximately 160 degrees; at the start of the curl, the movement is almost perfectly horizontal, straight forward – at about the midpoint, the movement is vertical, straight up – at the end, the movement is approximately horizontal again, but in the opposite direction.

Yet, during the entire movement, the resistance was always vertical, straight down. Thus, in practice, although the resistance remains constant, it seems to become heavier as the movement progresses from the starting position to the midpoint – and after the midpoint, seems to become lighter. In the normal finishing position of the curl., there is literally no resistance – having reached that point, it is then possible to hold that position almost indefinitely, with absolutely no work being demanded on the part of the bending muscles of the upper arms.

This occurs because during a curl the moment-arm of the weight is constantly changing as the movement progresses; DIRECT resistance is provided only at the infinitely-small point where resistance is being moved vertically.

A careful scrutiny of conventional exercises will clearly show that this is almost always the case; direct resistance is provided only within an extremely limited range-of-movement, literally an infinitely small range of movement – and in many conventionally exercises, there is no direct resistance at any point.

If the normal strength curve of human muscles exactly matched the apparently changing resistance provided by an exercise like the curl, then the movement would feel perfectly even; that is to say, no point in the movement would seem to be any heavier than any other point. But since, in fact, the strength curve does not match the change in resistance, some points do feel heavier than other points; so-called “sticking points” are encountered, where the weight feels very heavy, as well as points where there is little or no resistance.

Just as jumping is not the best means of moving forward, since it involves the expenditure of effort in a vertical as well as a horizontal direction, trying to provide a rotary movement with constant resistance by using a uni-directional form of resistance is impractical at the very least. In such a case, resistance will only be – can only be – provided during part of the movement.

Written by Arthur Jones.