How to Evaluate Fitness and Physical Therapy Equipment

By Joe Mullen

For the purpose of this article, we are comparing two basic types of exercise and therapy equipment:

1. Non High-tech, such as: free weights, wall pulleys, ankle and wrist weights, medicine balls, elastic bands, any kind of passive exercise and any other primitive form of exercise and physical therapy tool.
2. High-Tech, equipment that provides the requirements of very productive exercise. The difference between all will become apparent.

In l970, Arthur Jones introduced a commercially successful high-tech tool: Nautilus exercise equipment.

Initial critics of Nautilus and Arthur Jones, denounced him and his invention, stating he based his exercise philosophies and invention on information he created.

They are incorrect. It is true that he was the first man to integrate certain requirements for productive exercise.

It is also true, he did not create, many of these requirements. Instead, various scientists established these ideas after years of research, into anatomy, physiology, exercise science, and physics.

Mr. Jones was able to pull all facts together and present them clearly. Nautilus equipment was the logical extension of his search for an improved exercise tool.

A tool designed to meet the then known requirements, of full-range, productive exercise.

Until the high-tech breakthrough, and the invention of Nautilus equipment, the barbell was the universal tool used by health and fitness enthusiasts. Barbells and dumbbells are certainly easier to handle than the rocks, stones, and logs used by our ancestors.

Free weights, allowed specific design of exercises and the resistance adjusted, to the existing strength levels of an individual. The resistance adjusts as the person increased in strength and fitness.

Because the resistance adjusted to the individual and it is relatively low cost, it allowed the barbell to enjoy increasing popularly for 100 years.

Along with the use of the barbell, exercise routines evolved, that became standard exercise procedure. These exercise programs remain virtually unchanged.

Barbells' manufacturer’s branched out into diet supplementation. Thus, the vitamin and protein market merged into the fitness industry.

Magazines began to appear, touting one Barbell Company and its champions over the competition. Special food supplements were recommended for improved gains.

Claims and counter-claims continue to the present time.

Then the bomb exploded. Arthur Jones emerged and challenged traditional thinking. The exercise and physical therapy world have not been the same because of this challenge.

To understand why high-tech is more productive, one fact is clear: The quality of the application of resistance, to a working muscle determines the quality of the results.

Isometric, Isotonic and Isokinetic

Resistance is the basic requirement demanded for productive exercise.

There are three types of resistance used in an exercise and therapy programs: isometric, isotonic, or isokinetic. Any serious discussion of exercise tools would quickly eliminate isometric and isokinetic modes of exercise.

Among other requirements, they lack negative resistance potential; however, the static mode of strength testing is beneficial for establishing one aspect of functional ability.

Isometric exercise is also "static exercise or static testing." Static testing of muscular torque is the only valid way of testing for strength and muscular torque. Properly performed, it is virtually zero impact.

In addition, will determine ones muscular torque, in any angle tested. This is especially beneficial when testing an injured area for functional strength deficiency.

Positive/Negative Concentric/Eccentric Lifting/Lowering

Muscle tissue is capable, of lifting and lowering a resistance; stated another way, muscle tissue is capable of positive and negative work.

Positive work is a concentric contraction, while negative work is an eccentric contraction. Stated yet another way, muscles shorten when contracted and lengthen when uncontracted. There is no shortage of verbiage, regarding muscle function.

Positive work happens when muscles contract and shorten. Negative work requires a muscle to lengthen and comes out of its contracted position.

In a two-arm barbell curl, the positive movement takes place when curling the palm to the shoulders. As you lower the resistance, it is negative work.

A properly designed exercise or physical therapy tool MUST provide both forms of resistance. Isometric exercise devices and isokinetic devices do not supply both

Prestretch/Stretching

Along with positive and negative resistance potentials, the ability to stretch and pre-stretch a muscle is a design requirement of high-tech equipment.

Stretching defines as slowly and safely, pushing or pulling a body part into a position that temporarily exceeds the possible range of motion one could achieve, without the added pushing or pulling.

It relates to the joints, muscles, and connective tissue. Pushing or pulling on a body segment, is a form of adding resistance.

Appling the force slowly and carefully, reduces the injury potential and helps eliminate pain.

Pre-stretching takes place, as a muscle enters into a position of increased tension, before the start of a positive contraction.

Pre-stretch has two effects resulting in improved results: (1) the muscle is elastic, just like a rubber band, and stretching it before movement actually stores elastic energy that for use in the contraction.

In addition, (2) pre-stretch ignites a nervous system stretch reflex that calls upon additional muscle fibers for use in the upcoming movement.

Now, we have established four requirements for full-range, productive exercise and physical therapy. They are: (1) Positive work, (2) Negative work (3) Stretching, and (4) Pre-stretching. Let us continue and add a few more requirements to our list.

Balanced Resistance and Automatically Variable Resistance

As muscles contract and move through a range of motion, they do so with varying degrees of movement and strength potentials.

The degree of movement during a two-arm curl is different from the range-of-motion during a two-arm lateral raise

The muscle groups involved are of different strength potentials. The amount of resistance one use, for an overhead press is usually greater than used in the two--arm curl.

This requires the resistance is balanced. In accordance, with the range of motion and, varying strength potentials of the muscle groups involved in the movement.

Properly designed equipment, provides automatically variable resistance and balanced resistance. Both requirements are possible because of the cam system and outlined later.

As one moves through a range of motion, the resistance will varies automatically, according to the strength potential of the muscle group or groups performing the movement.

As muscle contracts and the leverage advantage and strength factors change, the resistance will change in balance with these factors.

This assures adequate resistance at all times. We have now established two more requirements: (5) Balanced resistance, 6) Automatically variable resistance.

Unrestricted Speed of Movement/Position of Full Contraction

It should be possible to perform exercise movements, in an unrestricted way, at various speeds, for high intensity of muscular contractions.

Throwing the resistance is not beneficial and is potentially damaging to the human structure; however, a requirement is unrestricted speed of movement.

For best results, move the resistance slowly. By controlling the movement, you insure that the muscle is in fact working against resistance.

Increasing the speed of movement, to the point commonly called an "explosive movement," compounds the force, and if a muscle is not prepared for the sudden jerk, injury will occur.

Without providing resistance in the position of full muscular contraction, it is impossible, to exercise through a full range of motion.

High-tech machines should provide resistance in the position of full muscular contraction. Many exercise tools and therapy tools in the marketplace do not.

We have already established that resistance, properly supplied, is the key to results in exercise and proactive therapy. Logically, the resistance must be applied directly to the muscle under contraction to insure best results.

This is logical, but many times impossible to do.

Here is an example. When performing a two-arm chinning movement, or overhead pull down movement, you will provide resistance primarily to the latissimus dorsi and biceps (and other arm associated muscle) of the upper body.

During the movement, the biceps will exhaust before the larger, stronger back muscles. Therefore, you would not exercise the latissimus dorsi muscles effectively.

A high-tech pullover machine supplies higher quality resistance to the latissimus dorsi muscle groups. By removing the weak link in the two-arm chinning movement, grip strength, and applying the resistance to the upper arms near the elbows, one works the back muscles more thoroughly.

This is one example of the high-tech exercise potential.

Now, we have established 9 of the 10 basic exercise requirements, required for designing a valid exercise machine:

1. Positive work.
2. Negative work.
3. Stretching.
4. Pre-stretching.
5. Balanced resistance.
6. Automatically variable resistance.
7. Unrestricted speed of movement.
8. Resistance in the position of full muscular contraction.
9. Direct resistance.

The 10th requirement we're listing, is one that makes most of the other requirements possible and could be listed as the #1 requirement in equipment design: It is called rotary form resistance.

The Cam

In simple terms, rotary form resistance defines as Resistance rotating on a common axis, with a body segment, moved by muscle contraction.

One great invention in the history of exercise is a device called the cam. The cam allows the 10 basic requirements, of full-range exercise, to be experienced.

The development of the cam, took many years, so an in-depth analysis of it, and the mathematical formulas involved is beyond the scope of this book.

In simple terms, the function of a cam is as follows:

The cam redirects resistance, allowing it to travel, in the same strength curve as the movement of exercised body segment, and the resistance, redirected, travels in a rotary motion, and in the same strength curve.

At the same time the resistance is applied directly OPPOSITE the intended movement

This insures that resistance is constantly pulling directly opposite the direction of muscle contraction.

This allows applied resistance to a working muscle, throughout a greater range of movement.

Barbells and some other forms of exercise equipment do not supply resistance in this manner.

They supply resistance in a "straight line manner," always directly down toward the ground. With weights, one encounters affective resistance when moving the resistance and body segments vertically.

For instance, during the two-arm curl, one meets resistance when the bar moves into about the halfway to shoulder position.

At that point, gravity pulls the bar directly downward. Resistance is felt in the biceps, as one is moving vertically.

At the beginning of the curl, the bar moves parallel to the ground. It is as if, one pushes a car on level ground, compared to lifting it.

During a curling movement, the elbows must be against the side, for the biceps to work maximally. In the mid range, one encounters favorable resistance.

Once the bar moves, out of mid-range, into to the shoulders, there is little or no resistance supplied to the biceps muscles.

Therefore, it is nothing more than a balancing act.

A cam transforms straight-line resistance, meaning the pull of gravity, into rotational resistance. Resistance travels in a curve (rotary fashion), always supplying resistance in a manner that is always pulling, directly opposite of one's movement.

Barbells supply resistance in a correct manner only during some of the movement. A machine equipped with a properly designed cam system supplies resistance always, and in correct proportions, during the movement, regardless of the body segments movements.

• Simply put, if there is no resistance, there is no resistance.
• No amount of repetitive sets of an exercise will produce maximum results, without resistance.
• For maximum results in minimum time, high-tech exercise is superior to all others.
• The logic of the 10 requirements just stated illustrate this fact.

Cams and Compound Movements

Now, having stated all the above, let us discuss one fact, we've never seen discussed in print, or heard talked about in person.

That is, the lack of proper, variable resistance, met in any compound movement, that is: any movement involving more than one joint and more than one body segment.

Since the invention of cam-driven resistance, manufacturers have sold equipment with cams for compound movements.

An example is Pulldown from overhead. This is a movement using many muscle groups of many varying strength potentials.

The movement involves the muscles of the lower arms: the grip and forearms; the muscles of the upper arms: biceps, brachial is, brachioradialis; the muscles of the chest; pectoralis (high and low), the deltoids (posterior, anterior and mid); the back muscles: high and low latissimus; abdominals and some triceps.

Given this, if one imagines designing a cam to meet all the various strength levels of the muscle contractions (variable, full-range resistance); it appears to us, to be an impossible task.

We therefore submit, the cost of a high-tech, variable--resistance Pulldown machine, is hardly worth the price. Supporters of variable resistance cams could stretch a point, and debate the merits of a machine that provides some variable resistance (even if incorrectly calibrated) as better than none at all.

From that point of view, they would be correct. When properly used.

Whether the cost difference is worth it, is questionable. Single joint movements and the cams designed for them, are much closer to the true strength curves of the muscles, than any cam-driven compound machine.

Since the invention of cam-driven resistance, manufacturers have sold equipment with cams for compound movements. An example is Pulldown from overhead. This is a movement using many muscle groups of many varying strength potentials.

The movement involves the muscles of the lower arms: the grip and forearms; the muscles of the upper arms: biceps, brachial is, brachioradialis; the muscles of the chest; pectoralis (high and low), the deltoids (posterior, anterior and mid); the back muscles: high and low latissimus; abdominals and some triceps.

Given this, if one imagines designing a cam to meet all the various strength levels of the muscle contractions (variable, full-range resistance) it appears to us, to be an impossible task.

What do you think?