PT on the Net Research

Pattern Overload - Part 2


In Part I of this article, I demonstrated how pattern overload occurs and how machine training directly relates to creating pattern overload. In this installment I will discuss:

  1. How avoiding pattern overload is crucial if you care at all about your joints
  2. Tips on how to avoid pattern overload.

Pattern Overload and Joint Health

Synchronization and Motor Unit Fatigue

Current research clearly shows that the nervous system is capable of not only recruiting a specific muscle needed to perform a problem movement pattern, but it can also selectively recruit specific motor units, or segments within a given muscle (22). When motor units (MU) are recruited to perform any movement (from a Preacher curl to a snatch), the body attempts to rely on asynchronous stimulation of the working units. This is an attempt to save energy (some MUs work while the others rest) and keep movements as smooth as possible (23).

In concert with asynchronous stimulation and up regulating motor unit activation from small to large (size principle), varying the path of resistance (bar path) is another important mechanism for conserving energy and preventing unwanted overload in specific tissues. This is clearly demonstrated by comparing the bar path of the traditional bench press and Smith machine bench press (Fig. 4). In fact, the body is so committed to energy conservation and protecting tissues from overload, as I previously stated, you could film the most elite lifters in the world and they would never produce the same bar path twice in a row!

Figure 4

While performing any machine exercise where there is a fixed axis of rotation or guided resistance, such as the Smith machine bench press (Figure 4), the population of muscle fibers experiencing maximum load is isolated. The MUs and muscle fibers most suited to move the working extremity in the chosen pattern and in the movement plane dictated by the machine will experience synchronization and fatigue much sooner than when performing the same exercise with free weights, or a 3-Dimentional freedom of motion.

As the fiber population specific to the movement pattern dictated by any given machine fatigues, one is left with progressively less dynamic control over the load and working joints, often resulting in insult to the working connective tissue, tendon and muscle fibers. As dynamic, or muscular, support for the relevant joints fail, it is common to see a lifter do one of two things. They either squirm around on the machine attempting to find new fiber populations to move the load, (which is a dangerous means of changing fiber populations) or they attempt to use the stored elastic energy, or potential energy, of working connective tissues to complete the final reps of the set. Classic examples of this are bouncing the bar off the chest during the bench press, bouncing the thighs off the torso during a leg press, or springing the shoulders at end range on the pec deck machine. The result: damage to ligamentous and capsular structures of joints, not to mention the potential derangement of the joint itself!

These are no small potatoes when you consider the fact that connective tissue heals considerably slower than muscle (see side bar) and that motor control may be compromised secondary to damaged mechanoreceptors in relevant capsular and ligamentous tissues.

Pattern Overload, Mechanoreceptor Damage and Joint Stability

Surrounding each joint is a joint capsule. This capsule is like the boot on a car’s ball joints. The capsule aids in joint stability at end ranges of motion, serves to lubricate the joint surfaces with its synovial membrane and is loaded with proprioceptive neurons called mechanoreceptors (Table 1). There are also mechanoreceptors in the ligaments surrounding joints and special pain receptors called nociceptors that may be found in the capsule, ligaments, articular fat pads and blood vessels (28).

When an individual trains on machines with poor technique and/or overuses any form of guided resistance, the resultant fatigue and loss of motor control in the relevant movement pattern and plane of movement often leads to overload of the passive joint structures. Being predominantly collagen, these structures do not stretch well and do not bounce back well from repeated stretch either. The analogy and question I ask my patients is, "Do you remember when you last pulled a can of soda or beer from one of the six packs with plastic loops holding them together? What happened when you tried to put a full can back in the loop because no one wanted to use it at that time?" The answer is always, "It wouldn’t stay in there any more." This is a simplified version of what happens when the joint capsule and/or ligaments are stretched in your body.

A joint with stretched capsular structures and articular ligaments begins to lose its optimal working relationships and eventually, particularly in the case of the shoulder, tries to fall out in positions specific to the dysfunction!

Joint Receptors Function

Type I

Low threshold, slowly adapting static and dynamic mechanoreceptors. Tonic reflexogenic effects on neck, limb, jaw and eye muscles. Postural and kinesthetic sensation. Pain suppression. Facilitate the tonic muscle system.

Type II

Fast adapting, low threshold dynamic mechanoreceptors. Phasic reflexogenic effects on the neck, limb, jaw, and eye muscles as well as pain suppression. Facilitate the phasic muscle system.

Type III

High threshold, very slow adapting receptors. Have the same characteristics as a golgi tendon organ.

Type IV

High threshold, nonadapting pain provoking nerve fibers. These fibers have tonic reflexogenic effects on the neck, limb, jaw and eye muscles. They also induce cardiovascular reflexogenic effects. Facilitation can cause guarding in the tonic muscle system.

TABLE 1. Joint Mechanoreceptors

With decreased passive support from ligamentous and capsular structures, there must be a proportionate increase of dynamic support by muscles. Should the aberrant joint complex be mildly traumatized, the intrinsic stabilizers, such as the rotator cuff of the shoulder, will be taxed with the burden of trying to maintain an optimal axis of rotation in the now dysfunctional joint complex. Should they become chronically fatigued from repeated exposure to work and exercise, coupled with the newly added burden of trying to maintain optimal working relationships in the joint, an eccentric rotation of the most mobile segment in the joint is likely (See Figure 5.).

Figure 5

An eccentric rotation of the joint commonly results in what chiropractors refer to as subluxation. The joint complex demonstrating some level of instability as a result of pattern overload commonly begins to make popping sounds and clunking noises that did not previously occur. If the condition progresses, pain is associated with the unusual joint sounds and the patient can usually tell the therapist exactly what movement causes the problem; very often the movement mimics the exercise that induced the injury!

Proprioceptive Deficits and Loss of Neuromuscular Control

As the capsule and articular ligaments become progressively imbalanced (tight in some areas relative to other areas), there is progressive dysfunction in the proprioceptive messages being sent to the central nervous system with regard to where the joint is in space. This produces what is called a "proprioceptive deficit."

The athlete or worker with a proprioceptive deficit may establish a format for the employment of varying muscle recruitment order in an attempt to effect changes in joint position, leading to pathological motions (29). It is common to begin noticing a loss of performance during activities that require fine motor control. For example, the exercise enthusiast with pattern overload in a shoulder, often from performing such exercises as the behind head lat pull down or pec deck with extreme ranges of motion, and who plays golf, will increasingly experience swing errors.

The result, as pattern overload progresses, is imbalance in the capsular and ligamentous structures of the shoulder that will not only send faulty information to the brain about proprioception (Figure 6), but there will also be compensatory facilitation of key muscles around the shoulder and possibly beyond.

Figure 6

Because the Type I mechanoreceptors are located in the most superficial portions of a joint capsule (28), they are the first to be damaged in any case of pattern overload that includes the joint capsule and ligaments. If the joint structure is damaged enough to traumatize the deeper fibers of the capsule, there will be destruction of Type II mechanoreceptors.

This is important to understand because the Type I mechanoreceptors communicate directly with the tonic muscles of the body and the Type II mechanoreceptors communicate with the phasic muscles of the body, facilitating these muscle systems respectively (30) (See Table 2).

Predominantly Tonic Muscles

Predominantly Phasic Muscles

Prone to Hyperactivity

Prone to Inhibition

Function

Posture

Movement

Susceptibility to Fatigue

Late

Early

Reaction to Faulty Loading

Shortening

Weakening

Shoulder Girdle - Arm

Pectoralis Major & Minor

Levator Scapulae

Trapezius (upper)

Biceps Brachii

Scalenes

Subscapularis

Sternocleidomastoids

Masticatory

Forearm Flexors

Rhomboids

Trapezius (middle)

Trapezius (lower)

Triceps Brachii

Deep Neck Flexors

Forearm Extensors

Supraspinatus

Infraspinatus

Serratus lateralis

Deltoid

Trunk

Lumbar and Cervical Erectors

Quadratus Lumborum

Thoracic Erectors

Rectus Abdominis

Pelvis – Thigh

Hamstrings

Iliopsoas

Rectus Femoris

Thigh Adductors

Piriformis

Tensor Fasciae Latae

Vastus Lateralis

Vastus Medialis

Gluteal Muscles

Lower Leg - Foot

Gastrocnemius

Soleus

Anterior Tibialis

Peroneals

Extensors of the toes

Table 2. Properties of Tonic and Phasic Musculature – Modified from (31) and (32).

When the capsule and ligament structures become overloaded and damaged, the resulting facilitation of the tonic musculature leads to the characteristic holding patterns and faulty movement patterns commonly seen by therapists and doctors. A classic example of tonic facilitation by tonic muscles surrounding the shoulder is seen in a postural holding pattern demonstrated by an elevated, forward-rounded shoulder with increased tone in the biceps, or increased postural elbow flexion. When performing movements such as lat pull downs, chin-ups, rows and shoulder abductions (with or without a dumbbell), the movement will be initiated from the upper trapezius with a shoulder-hiking action. In the case of shoulder abduction, there is often increased effort from the upper trapezius in the beginning of the motion to carry the arm through mid and upper ranges of abduction and there may be an associated pain with this movement.

The problem of pattern overload is not just localized to "the joint that hurts" per say. Clinical experience demonstrates that pattern overload patients often complain of "abnormal nagging pains of unknown origin." This is likely to result from faulty motor recruitment of muscles at distant locations. In fact, Dvorak and Dvorak have demonstrated what they refer to as a spondylogenic reflex syndrome (28, p. 38-40). Researchers placed traction and electrically stimulated mechanoreceptors at the C3-4 level and were able to record significant EMG (electrical activity) responses in muscles such as the sternocleidomastoid, trapezius, digastric, scalenes, triceps, rectus femoris and biceps femoris!

Their findings strongly suggest the electrical messages sent to the brain, as produced by varying intensities of stimulation and lines of pull on the joint capsule, may make the brain respond as if a corresponding preprogrammed pattern of motion were taking place. Dvorak and Dvorak identified this as distant recruitment patterns (28). For the individual suffering from pattern overload, this may present itself as an idiopathic hamstring strain, groin strain, muscle tear or spasm in a seemingly unrelated region.

Tips for Avoiding Pattern Overload on Machines

To avoid pattern overload and its many ramifications (expected and unexpected), I suggest the following precautions:

1. Avoid any machine that is ergonomically incorrect for your body

It is safe to say, that of the hundreds of machines available in gyms today, a very small percentage of them were designed by engineers with any training in human biomechanics, kinesiology or ergonomics. The result . . . a lot of machines that do not fit a lot of people!

If you attempt to use a machine and it does not seem to correctly adjust to your body’s dimensions, chances are it will induce mechanical trauma to your body.

Some classic examples are:

In any such case as described here, it is always best and most cost effective, both now and in the long run, to look for a corresponding free weight or cable machine exercise (cable machines are classified as free weights). However, as a last resort you may look for another machine exercise that better suits your body’s dimensions.

2. Avoid terminal ranges of motion

The whole concept of "training through the full range of motion" is getting out of hand! No one has ever said, "Move the weight through a full range of motion as identified by joints popping, tendons snapping, muscles straining and ligaments becoming lax!"

As I have outlined above, training through any range of motion that threatens the articular capsule and ligaments will lead to faulty neuromechanical control of your joints. This will not only significantly increase the chance of injury for the rest of your life, ( with the exception of expensive rehabilitation or surgical procedures) but such faulty training methods are a likely cause of lost performance in numerous sporting events, particularly those requiring fine motor control.

Examples of machine exercises that commonly provoke injury to the body that I consistently see in a clinical setting are:

The answer? Lower the load as far as you can comfortably, without your sacrum (bottom segment of your spine) ever coming off the pad! Another tip that many of my patients have found helpful is to find a bum bag, or fanny pack, that will hold a rolled hand towel. With the hand towel rolled to the thickness of your hand at your thenar eminence (thick part of your thumb muscles), place it in the bum bag and wear it lose enough so that it can be easily maneuvered around your body from front to back. Now, whenever on the leg press or any other machine producing a load that may flatten your back, simply place the bum bag behind you with the towel roll directly behind your belly button. This will protect you from excessive flattening of your lumbar spine under load, ultimately decreasing your chances of buying an orthopedic surgeon a new BMW!

3. Periodize your exposure to any form of guided resistance

It is best to limit your exposure to a machine to no more than four weeks at a time training on that machine, and no more than once every 3-5 days. Additionally, you should cycle off each specific machine for a minimum of two weeks and preferably for four weeks. By alternating exercises with this suggested frequency, you will decrease your chance of injury because you are allowing a healing response in the fatigued or traumatized tissues related to a specific pattern of motion. An added benefit is the development of more complete strength and motor skills due to the variety of motor stimulus.

With literally THOUSANDS of exercises available today, the only excuse for not being able to find alternative ways to condition any part of your body is mental laziness! My advice to you, novice or expert, is to read time-honored books on training, watch reputable training videos (I have produced about 50), consult a knowledgeable strength coach, or simply watch individuals in the gym that appear to have more than a dozen brain cells firing at one time. NEVER train a region experiencing joint or muscle pain

Pain always equals inhibition in the human body! If you are training in pain, you can rest assured that the muscles crossing any joint in pain are being shut off, resulting in progressive instability of the joint(s) related to that muscle. This is directly related to Hilton’s Law, which states: "The nerves which supplied the muscles and controlled the movements of the part (joint) also served the skin and other sensory surfaces which were connected with that part" (33). The net result, " no gain if you train in pain!"

If you are training in pain, learn how to use a Swiss ball. There are many methods to assess yourself and others, as well as exercise in the decompressive manner afforded by the Swiss ball (14, 34, 35). The Swiss ball also provides tremendous motor variety and can be used with many forms of resistance apparatus (36) limiting your chances of pattern overload to a bare minimum!

If you are training in pain, you can rest assured that the muscles crossing any joint in pain are being shut off, resulting in progressive instability of the joint(s) related to that muscle. This is directly related to Hilton’s Law, which states: "The nerves which supplied the muscles and controlled the movements of the part (joint) also served the skin and other sensory surfaces which were connected with that part" (33). The net result, "If you are training in pain, you will serve yourself well to learn how to use a Swiss ball. There are many methods to assess yourself and others, as well as exercise in the decompressive manner afforded by the Swiss ball (14, 34, 35). The Swiss ball also provides tremendous motor variety and can be used with many forms of resistance apparatus (36) limiting your chances of pattern overload to a bare minimum!

Conclusion

Pattern overload is a very common, but frequently overlooked source of musculoskeletal injury. To reduce chance of injury, care should be taken to periodize the use of machines and activities that require chronic exposure to any specific movement pattern. The stabilizer system of the body should always be cleared as sufficient and capable of handling the repetition and loading of any movement pattern before it is performed. Careful attention should be given to the selection of exercises and their order of execution. Any individual suffering from pattern overload will be well served to seek advice from a professional in the field of strength and conditioning and/or orthopedic rehabilitation. Those suffering from, or wanting to prevent pattern overload in themselves or their clients, will find studying programs teaching proper exercise technique very helpful (8, 11, 12, 13, 14, 15, 16, 34, 35, 36, 38).

Pattern overload is a very common, but frequently overlooked source of musculoskeletal injury. To reduce chance of injury, care should be taken to periodize the use of machines and activities that require chronic exposure to any specific movement pattern. The stabilizer system of the body should always be cleared as sufficient and capable of handling the repetition and loading of any movement pattern before it is performed. Careful attention should be given to the selection of exercises and their order of execution. Any individual suffering from pattern overload will be well served to seek advice from a professional in the field of strength and conditioning and/or orthopedic rehabilitation. Those suffering from, or wanting to prevent pattern overload in themselves or their clients, will find studying programs teaching proper exercise technique very helpful (8, 11, 12, 13, 14, 15, 16, 34, 35, 36, 38).

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