Neuromuscular Training in Pain Management
How many people would think of using some form of exercise as primary pain management? If you’re the typical practitioner who perhaps doesn’t get the opportunity to read the latest research in the sport sciences, you might answer, “Not many.” In this clinical report, I would like to draw attention to the increasing body of research appearing in both the strength/conditioning and pain therapy realms that is providing evidence for lumbo-pelvic core stabilization training as a method to restore normal function while, at the same time, reducing spinal pain. There is still continuing debate as to which specific methods are the best, but a general consensus is forming regarding the presence of a muscle impairment component to many of the mechanical/ idiopathic low back pain syndromes being seen by practitioners today.1 The phrase ‘core stabilization training’ has become popular and somewhat in vogue with trainers and therapists alike. Stabilization is not the same as strengthening yet many practitioners continue to use the terms synonymously. The Redcord method of core stabilization was developed in Norway in the 1990s and represents one of the most popular techniques for specific core stabilization treatment through neuromuscular re-activation (neurac). We will begin our discussion with semantic clarifications while examining the main premise behind Redcord therapy.
Strength vs Stabilization
There have been many methods or systems of strength training that have evolved over the years. It is thought that most of these methods have contributed substantially to strength training and functional restoration. The most common training techniques, in the order that they became popular, have generally been categorized under the contraction type and/or load imposed on the muscle:
- isometeric – resistance against immovable force
- isotonic – resistance provided by a weight/plate
- isokinetic – for every 1 unit of force there is 1 unit of resistance; water therapy and elastic bands are considered crude forms of isokinetic resistance
- isoinertial – systems controlling acceleration/deceleration
- isodynamic – systems controlling motion
More recently we have seen the advent of functional and hybrid training methods which re-focuses the goal on grooving movement patterns as opposed to isolating a particular muscle group. Rehabilitation specialists take more care these days in training coordinated, balanced and integrated movements, as opposed to simply improving strength/muscle endurance of an injured muscle/joint
There are three types of contractions or actions that occur in muscle: concentric, eccentric (both dynamic), and isometric (static) contractions. In concentric muscle actions, the muscle contractile units shorten and is also known as a positive contraction. In eccentric actions, the muscle contractile units develop tension while simultaneously lengthening and is also known as a negative contraction. When a muscle develops tension but does not shorten or lengthen, this is referred to as an isometric action. Human function consists of all three types of muscle actions, but mostly eccentric. When persons are strength training, they typically are working toward increasing the contractile properties of muscle and will do so in all three mode combinations. Lumbo-pelvic core stabilization is a neuro-muscular event and does not necessarily refer to simply increasing the tensile or contractile properties of muscle—rather, it refers to the ability of a muscle or muscle group to activate in support of a movement not in actual motion itself.
Peripheral Joint Stabilization
Stabilization is a motor control strategy that serves to protect a vulnerable area such as a joint or series of joints as in the spine. As an example, in the periphery, when shoulder elevation occurs in a healthy individual there is a simultaneous contraction or action of the deltoid which acts as the primary mover, and the rotator cuff muscle group which acts as a stabilizer. In this case, the rotator cuff muscles hold the head of the humerus steady as the deltoid acts against this stabilization force to elevate the humeral segment via a concentric contraction. As the arm is released, the rotator cuff group maintains the position of the humeral head in the glenoid fossa as the deltoid produces an eccentric contraction thereby allowing the arm to drop back down in a controlled manner. This is an example of a force-couple situation and is common in peripheral joints. In this example we see the deltoid as the primary mover and the rotator cuff muscles as the stabilizers or secondary muscles acting to support the primary movers (synergists). In a pure shoulder external/internal rotation situation, the roles of the muscles are reversed with rotator cuff muscles acting as the primary movers causing rotation while the deltoid muscle acts to stabilize this motion with a concurrent isometric contraction. What we learn from this simple example is that muscles have various functions including direct generation of motion in a joint as a primary mover or acting as a stabilizer to support other muscles in motion.
Muscles function in different ways depending on the situation. They can act to generate strength so as to move a bony lever (arm or leg) through a range of motion thus creating joint torque. They can also act to support or stabilize a movement such as that described with the shoulder.
Peripheral joint stabilization in the knee and shoulder, for instance, involves co-contractions whereby the agonist (primary mover) and antagonist muscle groups contract or turn on at the same time, creating stiffness or stability in a joint. In the knee, there is co-contraction during weight acceptance in the gait cycle. Proper functioning of the peripheral joints involves not only co-contraction, but also reciprocal inhibition of antagonists during agonist activity. Using the example of gait: when the knee extensors, or agonists, contract during leg swing, there should be a simultaneous graded reduction (inhibition) in knee flexor activity. Without this reciprocal inhibition, there would be two opposing muscle contractions (co-contraction) leading to joint fixation or rigidity—not conducive to effective locomotion. This coordination involves timing and sequencing of muscle activity and leads to a smooth rhythmic motion. The central nervous system is the mechanism by which the timing and sequencing of muscle dynamics is coordinated and harmonized into a seamless and connected series of movements. It is this fine and precise neuromuscular control mechanism that appears to become disrupted as a result of injury or surgery to the spine.2