Torque, how can it be explained?

Torque has a somewhat bad reputation in bodybuilding; generally, it is used in terms of the rotator cuff, but is there more to it?

In a few words, torque is the ability of a force to cause a lever to rotate (moment of force); however, the more detailed definition is a force applied over a distance (lever arm) that causes rotation around a fulcrum (axis of rotation).

Spending time stretching and contracting is not necessarily useful, although a full range of motion is always necessary.

We emphasize this because you should not cheat during a movement; you should focus solely on the muscle of the day and try to eliminate any extraneous movement. We would like to play devil’s advocate here and suggest a way that cheating can, to some extent, be used to your benefit.

It all comes down to one word: “torque.”

What about torque?

Torque in the rotator cuff is terrible, but that tends to limit the perception of this term, as if having any kind of torque in a limb were a bad thing (just as “momentum” has been demonized).

To properly evaluate “torque,” we need to define it.

It is a twisting effort … “a force that (produces) rotation or twisting” … in short, whenever we have something rotating due to force, we have torque.

In bodybuilding terms, whenever a limb rotates with weight on it, we are dealing with torque, and this is what occurs every time a weight is lifted.

How is this measured?

Physics teaches us that it is the product of a force multiplied by the length of the torque arm.

If one makes one side of a seesaw longer than the other, less weight is needed to lift the fat child on the other side.

In other words, the farther the weight is from the joint, the harder it will be to push, and this is why flyes are harder to do than dumbbell presses with the same weight … more torque …

This may be more difficult to conceptualize in the weight room, but here is one way to think about it: compare a fly or a pullover with bent arms to one performed with fully straightened arms.

It is much less difficult with bent arms, right?

This is due to the fact that straightening your arms places the weight farther from your body, which increases the amount of torque in your muscles.

The dumbbell lateral raise is another example of this principle applied to a classic exercise; the straighter and farther you move your arms from your body, the harder the exercise will be.

Generalizing things

Measuring the torque exerted by muscles is fundamental to many aspects of rehabilitation, industrial design, ergonomics, and peak athletic performance.

For example, designers of medical equipment for older people design devices that require little torque to operate, while exercise-equipment designers expect their users to generate a large amount of the factor under discussion.

However, muscle torque itself is difficult for non-specialists to define and quantify.

Basic force comes from a group of muscles, which can push or pull, and the axis in the equation is the joint controlled by the muscles.

A third factor in the calculation is the length of the limb or muscle group involved, which determines the leverage used to apply the force.

All these factors come into play when calculating muscle torque, but the basic mathematics is complicated by technicalities.

The fact that some muscles push while others pull, and that human joints operate in three dimensions rather than two, should always be taken into account.

 

Calculating muscle torque

Muscle torque is calculated through the interaction of these three factors.

• The first is the actual force generated by the muscles themselves.
• The second is the length of the limb or muscle group applying the force, which determines how much leverage can be applied. This measurement is known in physiology and biomechanics as the “moment arm.”
• The third factor is the angle formed by the moment arm and the joint at the moment the force is applied.

Muscle torque is therefore the force applied by the muscles through a moment arm of a given length, at a given angle to the joint.

However, the actual calculation can be significantly more complicated, both because the joint angle often changes during the movement that creates the torque and because joint rotations may not be planar but three-dimensional.

On the other hand, the length of the moment arm may change during some movements as the relevant muscles contract.

The mathematics required to accurately calculate muscle torque is beyond the average person’s scope, but specialists can generally arrive at an accurate measurement in “pound-feet” or “newton-meters.”