Today’s society is plagued by postural imbalances. More than ever before, flexibility training has become a key component to developing neuromuscular efficiency and decreasing these dysfunctions. Flexibility training can decrease the chance for muscle imbalances, joint dysfunctions and overuse injuries. Without optimum levels of flexibility, it is impossible to have proper kinetic chain function and performance.1,2,3,4,5,6 Therefore, it is critical for the personal trainer to gain appropriate knowledge of flexibility-training in order to properly design an integrated training program. This knowledge includes an understanding of flexibility training as a complex and highly dynamic process necessary to achieve optimum results.1,2,3,4,5
Flexibility is the normal extensibility of all soft tissues that allow the full range of motion of a joint.1 However, in order for our soft tissue to achieve efficient extensibility, we must have optimum neuromuscular efficiency (control) throughout the entire range of motion.4,7,8 This is referred to as dynamic range of motion. Thus dynamic range of motion is the combination of flexibility (soft tissue extensibility) and neuromuscular efficiency. Neuromuscular efficiency is the ability of the neuromuscular system to properly recruit agonists, synergists, stabilizers, neutralizers and antagonists to produce force (concentrically), reduce force (eccentrically) and dynamically stabilize (isometrically) the entire kinetic chain in all three planes of motion.4,5
Therefore, flexibility must allow us to properly move in a multiplanar fashion needed for everyday activities such as bending over to tie our shoes or reaching in the top cupboard for dishes. . This is referred to as dynamic functional flexibility and is defined as integrated multiplanar soft tissue extensibility with optimum neuromuscular efficiency throughout the full range of motion and is achieved through integrated flexibility training.4,5 Thus integrated flexibility training is a multi-faceted approach integrating various flexibility techniques to achieve optimum soft tissue extensibility in all planes of motion.
To provide a better understanding of integrated flexibility, a few important concepts must first be reviewed: the kinetic chain, muscle imbalances and neuromuscular control (efficiency).
Current Concepts in Integrated Flexibility Training
Kinetic Chain Review
The kinetic chain is comprised of the muscular, skeletal and neural systems. Optimum alignment and function of each component of the kinetic chain is the cornerstone to a sound integrated training program. If one segment of the kinetic chain is misaligned and not functioning properly, predictable patterns of dysfunction develop.4,5,7,8,9,10,11 This misalignment and dysfunction leads to decreased neuromuscular efficiency and tissue overload. The predictable patterns of dysfunction are referred to as postural-distortion patterns.4,5,7
The ultimate goal of the kinetic chain is to maintain dynamic postural equilibrium. To do so, it must have an adaptive potential. Limited flexibility decreases the kinetic chain’s adaptive potential, leading to muscle imbalance, joint dysfunction and decreased neuromuscular control.4,8 In addition, poor flexibility leads to the development of relative flexibility, which is the phenomenon of the kinetic chain seeking the path of least resistance during functional movement patterns.4,8,12
A prime example of this is seen in people who squat with their feet externally rotated. As most people today have tightness in their calf muscles, they lack the proper amount of dorsiflexion at the ankle to perform a squat with proper mechanics. By widening their stance and externally rotating their feet they are able to decrease the amount of dorsiflexion required at the ankle to squat and thus compensate for this lack of flexibility. However, if you have them perform a squat with their feet straight, you will probably see their feet “peel-out” or begin to externally rotate (see overhead squat assessment). This is not supposed to happen. Proper squat mechanics are performed with the feet straight ahead (unless for a very specific and rare case where the feet are very wide apart). Because most people lack dorsiflexion, they compensate by externally rotating their feet since this is where their feet “want” to go. Essentially, they go where their body wants them to go (the path of least resistance). This, in turn, leads to and becomes ‘relative flexibility’.
Muscle imbalances are an alteration in the lengths of muscles (length-tension relationships) surrounding a given joint where some are shortened or tight and others may be lengthened, weakened and/or inhibited.4,5,7,10 Muscle imbalances can be caused by a variety of mechanisms:1,4,5,8,12
- Postural stress
- Emotional duress
- Pattern overload and repetitive movement
- Cumulative trauma
- Poor technical skill
- Lack of core strength and neuromuscular control (efficiency)
Scientific Rationale for Integrated Flexibility Training
Integrated flexibility training is a key component for all training programs. It is utilized for a variety of reasons, including to:1,4,7,8
- Correct muscle imbalances
- Increase joint range of motion
- Decrease muscle hypertonicity (increased activity)
- Relieve joint stress
- Improve the extensibility of the musculotendinous junction
- Maintain the normal functional length of all muscles
- Improve optimum neuromuscular efficiency and function
Benefits of Flexibility Training
Perhaps the biggest benefit of integrated flexibility training for today’s clientele is the ability to help correct muscular imbalances. Figure 1 outlines the affect muscle imbalances have on the kinetic chain. Muscle imbalance leads to a variety of dysfunctions mentioned in the previous sections that include reciprocal inhibition, synergistic dominance and arthrokinetic dysfunction.
Figure 1. The Affect of Muscle Imbalance on the Kinetic Chain
When reviewing the primary causes of muscle imbalance, the need for integrated flexibility training should be very clear. How many people in today’s society have altered posture, emotional duress or pattern overload? Pattern overload is consistently repeating the same pattern of motion. This is similar to the gym member who trains the same way, with the same routine, at the same speed, in the same plane of motion on the same days. How about repetitive stresses placed on the body? Consider the person who is involved in sports or who has a particularly repetitive occupation (construction worker who is bent over and hammering all day or a loading-dock employee lifting and loading packages all day). Even sitting at a computer is a repetitive stress.
To fully appreciate the principles of flexibility, the trainer must understand the different types of flexibility. Flexibility, like any other form of training, should follow a systematic progression. This is known as the Integrated Flexibility Continuum.4,5 There are three phases of flexibility training: corrective, active, and functional (Figure 2).1,4,13,14
Corrective Flexibility is designed to improve muscle imbalances and altered arthrokinematics.4,5 it uses static stretching and self-myofascial release (foam roller) techniques (Figure 2).
Active Flexibility is designed to improve the extensibility of soft tissue and increase neuromuscular efficiency by using reciprocal inhibition and autogenic inhibition.4,5 Active flexibility allows for agonists and synergist muscles to move a limb through full range of motion while the functional antagonists are being stretched.4,15,16 For example, a supine straight-leg raise utilizes the hip flexor to raise the leg and hold it unsupported, while the antagonist hamstring group is stretched. Active flexibility uses active isolated stretching and self-myofascial release techniques (Figure 2).
Functional Flexibility is the most crucial form of flexibility to obtain, and should be the focus of all flexibility programs. Functional flexibility is integrated, multi-planar soft tissue extensibility with optimum neuromuscular control through the full range of motion (Figure 2).4,5
Remember that all functional movements occur in all three planes of motion, and injuries most often occur in the transverse plane. If the appropriate soft tissue is not extensible through the full range of movement, the risk of injury dramatically increases.2,17 Exercises that increase multi-planar soft tissue extensibility and have high levels of neuromuscular demand are preferred.
Figure 2. Integrated Flexibility Continuum
Proper forms of stretching are one means of enhancing flexibility and can also be viewed on a continuum. Each type of flexibility in the flexibility continuum consists of specific forms of stretching. Table 2 shows the match-ups. For example corrective flexibility uses static stretching, active flexibility uses active stretching and functional flexibility uses dynamic stretching. Each form of stretching manipulates the receptors and the nervous system, which in turn allows for the alteration of the muscle extensibility.4,5
|Table 2. The flexibility continuum with stretching examples.
||Wall Chest Stretch
|Self Myofascial Release
||IT Band on foam roll
||Supine Straight Leg-Raise
||Self Myofascial Release
Static Stretching is the process of passively taking a muscle to the point of tension and holding the stretch for 20 seconds.1,2,4 This style of stretching combines low force with long duration movements18 The proposed mechanism for this type of stretching is autogenic inhibition.5 By holding the muscle in a stretched position for a prolonged period of time (20 sec), the GTO is stimulated and produces an inhibitory effect on the muscle spindle. This allows for elongation of the soft tissue.4,5,7,19 This is the traditional form of stretching that is most often seen in fitness venues today. Static stretching should be used to defacilitate a tight muscle prior to activity and to “reset” soft tissue following activity.5 An example of static stretching is simply placing your arm on the wall and “hold” a pectoral stretch for twenty-seconds.
Active Stretching is the process of using agonists and synergists to dynamically move the joint into a range of motion.4,14, This creates reciprocal inhibition of the functional antagonists and allows for greater ranges of motion to be accessed. The supine straight-leg raise stretch is an example of active stretching.1,4 By contracting the quadriceps and hip flexors to pull the leg up off the floor you enhance the stretch of the hamstrings in two ways. First, by increasing their length and second, the contraction of the quadriceps and hip flexors causes reciprocal inhibition of the hamstrings allowing them to elongate without as much excitation. This form of stretching increases motorneuron excitability and is suggested for pre-activity warm-up if no postural distortion patterns are present or they are significantly reduced.5 Typically, 10 repetitions of each stretched are performed and held for 2 seconds each.
Dynamic Stretching uses the force production of a muscle and the body’s momentum to take a joint through the full available range of motion. Leg swings are a good example of functional stretching.1,4 Functional stretching is also suggested as a pre-activity warm-up if no postural distortion patterns are present or they are significantly reduced.5
Self-Myofascial Release (SMR) is another form of flexibility training that focuses on the fascial system in the body. By applying gentle force to the fascial restriction (adhesion or “knot”) the elastic collagenous fibers are manipulated from a bundled position (that causes the adhesion) into an alignment that is straighter with the direction of the muscle and/or fascia. The gentle pressure will also assist in releasing the knot by stimulating the GTO and thus autogenic inhibition.4 It is crucial to note that when a person is using SMR they must find the tender spot (this indicates an adhesion) and sustain pressure on that spot for a minimum of 20-30 seconds.4 This is to activate the autogenic response. This may take longer and will depend on the client’s ability to consciously relax.
This process, in turn, will help restore the body back to an optimal level of function and performance by resting the soft tissue proprioceptive mechanisms.20 Self-myofascial release is also suggested prior to static stretching for postural distortion patterns and/or activity as well as a useful warm-down.
Though there are many types of flexibility training, no single method can improve every flexibility deficit. The best flexibility program follows the Integrated Flexibility Continuum. Remember that the goal of any flexibility routine is to create multi-planar soft tissue extensibility that is controlled by the central nervous system in a progressive manner.
Practical Application of Integrated Flexibility Training
Current Research has demonstrated that static stretching prior to activity decreases motor unit recruitment, motor unit synchronization, and rate of force production.14,21,22 This would be contraindicated prior to initiating dynamic functional activities. Active flexibility and functional flexibility decrease antagonistic inhibition and increase motorneuron excitability.23 It is more appropriate to perform a controlled dynamic functional warm-up prior to activity and then to perform static stretching for a warm-down following the workout. If, however, an individual exhibits muscle imbalances, joint dysfunctions, and postural distortions, then corrective-flexibility exercises (self-myofascial release and/or static stretching) should be implemented prior to the controlled active/dynamic warm-up to ensure appropriate movement patterns and prevent relative flexibility.4,5
Flexibility for Postural Distortion Patterns
As previously mentioned in this chapter as well as the assessment chapter, there are three main postural distortion patterns. They are the lower crossed syndrome, upper crossed syndrome and pronation distortion syndrome. When these distortion patterns are noted in your client following their assessment, each must be properly addressed to achieve a successful program. Proper flexibility is the first step to address these problems.
|Corrective Flexibility for Postural Distortion Pattern
|Postural Distortion Pattern
||Stretches and SMR
|Lower Crossed Syndrome
- Iliopsoas/Rectus Femoris
- Hamstrings (SMR)
- IT Band (SMR)
|Upper Crossed Syndrome
- Levator scapulae
- Upper trapezius
- Latissimus dorsi (SMR & Stretch)
- Pectoralis major/minor
|Pronation Distortion Syndrome
- Iliopsoas/Rectus Femoris (SMR &/or Stretch)
- Adductors (SMR &/or Stretch)
- Gastrocsoleus (SMR &/or Stretch)
- Hamstrings (SMR)
- IT Band (SMR)
There are many stretching exercises designed to improve flexibility. Regardless of the method employed, flexibility can be achieved by manipulating many acute variables such as the duration and intensity of the stretch and the velocity and frequency of the movements performed. To achieve optimum dynamic functional flexibility (soft tissue extensibility with neuromuscular control), the individual should follow the Integrated Flexibility Continuum (corrective, active, and functional). The risk of injury is reduced when these stretching techniques are combined with an integrated training program focusing on neuromuscular efficiency at all levels. Further research is needed to determine which flexibility technique is right for a given individual.
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- Clanton TO, Coupe KJ. Hamstring strains in athletes: diagnosis and treatment. J Am Acad Orthop Surg Jul-Aug 1998;6(4):237-48.
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