• Flexibility and stretching - Definitions
  • Flexibility and the martial arts
  • Basic physiological structures of importance
  • Types of stretching: their advantages and disadvantages
  • Stretching as part of training

Flexibility and stretching - Definitions

In this discussion, flexibility is the range of normal motion of part of the body about a joint. It varies between different joints and between different sides of the body in the same joint. Gender, age and genetics play a part.

Stretching means any exercise intended to increase flexibility. I use two kinds of stretching: Preparation stretching helps the body to undertake exercise by loosening the muscles, Expansion stretching consists of exercises intended to increase the range of motion. These are not a separate set of techniques, rather their purpose, intensity (and discomfort) differ.

Flexibility and martial arts

An obvious demonstration of flexibility in martial arts is a kick to the head. This requires sufficient flexibility for the foot to raise and strike the opponent across the face, temple or other area. However, flexibility is also important in low and mid-level kicks, punching, striking, and evasion. For example, front kicks to the sternum using the heel of the striking foot require sufficient flexibility in the upper leg and lower back to draw the leg into the chest before it is driven forward into the target.

Basic physiology

Understanding muscle and joint structures assists the understanding of how to increase flexibility, and how each stretching exercise works.

At its most basic, the human body is a machine built around a frame (skeleton) linked by connective tissue (tendons) to contracting tissues (muscles) that create movement. Joints between parts of the frame also have connecting tissues to ensure stability (ligaments). Within the muscles, tissues of importance to flexibility and stretching include the sheaths (or fascia) that separate individual muscles from each other and individual parts of each muscle, and various nerves that trigger reactions within the muscle to enable movement and prevent injury.

All of these structures are important in determining the degree of flexibility. Bones and ligaments act as barriers to movement in certain positions (for example, the meeting of the humorous, ulna and radius prevents the lower arm extending backwards when the arm is straightened). Muscle sheaths also contribute significantly to restrictions on flexibility, with tendons and skin someway behind in their influence.

Other key contributors are involuntary nervous reactions within the muscle. Reciprocal Innervation controls muscle tension to allow movement. Simply, muscles are grouped in pairs (such as the biceps and triceps on the upper arm). When one side of the pair contracts, the other side relaxes and movement occurs; without this reaction no movement would be possible.

Muscles also contain protective devices. These include the Stretch Reflex and Inverse Myotatic Reflex. The Stretch Reflex is triggered by any sudden increase in muscle length. To prevent injury, this reflex causes a rapid contraction in the muscle to counteract the increase. The Inverse Myotatic Reflex counteracts high levels of muscular tension. Receptors in the muscles monitor how tense the muscle has become. Once tension increases beyond a certain point, these receptors trigger a sudden relaxation of the muscle, preventing the muscle and tendons being torn away from the bone.

Stretching techniques

The greatest degree of increase in flexibility comes from lengthening the muscle sheaths and the muscles themselves. All stretching requires relaxation of the target muscle to attain success, though is some active muscular contraction is also required. Some stretching techniques exploit the nervous reactions within the muscles. All techniques have advantages and disadvantages. All stretching carries a risk of injury, though some techniques have a higher degree of risk than others.

Static Stretching: (e.g. the splits). This allows for the greatest degree of control by the student and so is the safest. This type of stretching features heavily in Preparation stretching. Muscles are pushed as far as the student is willing to go and are held there. There may be subsequent further stretching after a period of time. This approach has the advantage that the body has time to deal with the nervous reactions (e.g. the Stretch Reflex). Its main disadvantage is its lack of specificity and (basically) that it does not involve movement! For example, a forward stretch will elongate the hamstrings (back of the thighs) and lower back, but a kick may involve these muscles, and the quads (front of thighs), obliques (side of the body) and calf muscles (base of leg), and place different demands on the supporting side and kicking side of the body.

Ballistic Stretching: (e.g. 'bouncing' at the furthest extent of the four-foot exercise) . This involves using momentum from movement to force the body to increase its range of motion. Ballistic stretching carries increased risk, as there is little or no time for the body to accommodate the nervous reactions induced. Ballistic stretching should only be undertaken by advanced students under the supervision of their instructor; beginners should never practise it.

Dynamic Stretching: whilst is also involves movement to expand the range, this is preferable to ballistic stretching, as it avoids jerky or bouncing movements. Front leg stretching is an example of this technique. It can be used as a Preparation stretch.

Passive stretching: This involves assistance from a training partner who applies force to push the body's range of motion beyond the limits the student can achieve on their own. It relies on good communication between training partners to prevent injury. It is a useful Expansion stretch technique.

Active stretching: This uses the students own muscles. Free active stretching is done without external influence (e.g. standing against a wall and lifting your leg as high as it will go). Resistive active stretching involves contracting the muscles against an opposing force (e.g. a training partners legs or shoulder). The advantages of this technique is that is can increase dynamic flexibility (it involves muscular contraction whereas static stretching does not). However, it can be difficult to overcome the nervous reactions that inhibit stretching.

Proprioceptive Neuromuscular Facilitation (PNF): This technique seeks to exploit the natural nervous reactions in order to increase stretching effectiveness. Contact-Relax Technique involves contracting the target muscle groups (in order to induce the Inverse Myotatic Reflex) followed by relaxation and (immediate) further stretching by a training partner. Contract-Relax-Agonist-Contract involves conscious contraction of the partner muscle to the target (e.g. the quads during a hamstring stretch) in order to take advantage of Reciprocal Innervation. Whilst this form of manipulation requires some work to master, it can be a useful Expansion stretch technique.

Stretching during training

There is no consensus in literature about when or how stretching programmes should be built into training, nor the right duration for each individual stretch. Certainly, stretching should normally be proceeded by a warm up (i.e. exercises designed to raise the heart rate and blood flow to the muscles). There are obvious advantages to Expansion stretching during summer when the ambient temperature is higher. Any stretching during winter must be preceded by a longer warm up to ensure that muscles are properly readied.

In terms of duration, sports texts recommend 30 seconds for individual stretches, or ten seconds where the stretch is to be repeated.

As with all exercise, frequency is key. Increases in flexibility do not fade as quickly as aerobic fitness (static stretching can induce changes in muscle fascia that are described as 'semi permanent'), but if you do not stretch for some time, there is an increased risk of injury if you attempt to reach as far as you did when you last trained.

In my experience, Preparation stretching induces tension, Expansion stretching induces discomfort. Neither should induce pain. The line between pain and discomfort is sometimes fine; only the student knows where they are at any one point.

Any sharp pain is a clear signal from the body to stop. Other times not to stretch are: - There is a bone in the way(!); - You live with osteoporosis; - You will be working with a bone that has recently been fractured or broken; - There is joint inflammation (such as a sprain or strain); - The joint lacks stability; - There is a loss of function or a decrease in the range of motion following stretching.

Students who train with me will find that I tend to follow a regular pattern of stretches and warm up exercises at the start of the class. These are intended to prepare major muscle groups for exercise. I pay particular attention to the lower back, obliques and legs, but shoulders, thorax and neck always receive attention.

In my own personal training, I always prepare major muscle groups for work, even if I'm only going for a short run. That said, I'm not arguing that a full warm up is required before running for a bus.

I have also found that correct posture in stretching is vital, particularly any stretch involving the back. Two incorrect postures for the back are: - Rounded, e.g. during a forward stretch over straight legs; and - Excessively arched, e.g. when lowering backwards from a kneeling position.

Tricks to avoid this are imaging that a rod has been placed down the back of your uniform, and your head's been taped to it! As you stretch, use the in-breath to check your back's posture and stretch forward on an out breath trying to maintain this straightness. If you're assisting someone to stretch, place your hands on their lower back, not near the shoulders and try to push forward smoothly, relax them out of the stretch smoothly as well. To avoid excessive rounding and arching, a yoga trick is to pull your belly button in towards the spine and to think of the front and back of your body being even in length.


This article is based mainly on my own experience. Some of the definitions and descriptions of various techniques are based on Sports Stretch: 311 Stretches for 41 Sports. Second Edition by Michael J. Alter Human Kinetics 1998. San Da students can borrow this excellent publication from the article author.

Please note: In presenting this article, I make no guarantees of success, or freedom from risk or injury from exercise, including stretching, and will not be held liable for such.