Tiger Athletic Fitness & Conditioning is a private, appointment only strength & conditioning gym in the heart of Sandton offering tailor made, goal-oriented fitness programs. This is the second of three resources, a modest attempt to address some of the frequently asked questions about stretching and flexibility. Here we take a closer look at flexibility.

Many people are unaware of the fact that there are different types of flexibility. These different types of flexibility are grouped according to the various types of activities involved in athletic training. The ones which involve motion are called dynamic and the ones which do not are called static. The different types of flexibility are:

  • Dynamic flexibility – also called kinetic flexibility is the ability to perform dynamic (or kinetic) movements of the muscles to bring a limb through its full range of motion in the joints.
  • Static-active flexibility – Static-active flexibility also called active flexibility is the ability to assume and maintain extended positions using only the tension of the agonists and synergists while the antagonists are being stretched. For example, lifting the leg and keeping it high without any external support.
  • Static-passive flexibility – also called passive flexibility is the ability to assume extended positions and then maintain them using only your weight, the support of your limbs, or some other apparatus (such as a chair). Note that the ability to maintain the position does not come solely from your muscles, as it does with static-active flexibility. Being able to perform the splits is an example of static-passive flexibility.

Research has shown that active flexibility is more closely related to the level of sports achievement than is passive flexibility. Active flexibility is harder to develop than passive flexibility (which is what most people think of as “flexibility”); not only does active flexibility require passive flexibility to assume an initial extended position, it also requires muscle strength to be able to hold and maintain that position.

Factors Limiting Flexibility

Flexibility (mobility) is affected by the following factors:

  • Internal influences.
  • The type of joint (some joints simply aren’t meant to be flexible).
  • The internal resistance within a joint.
  • Bony structures which limit movement.
  • The elasticity of muscle tissue (muscle tissue that is scarred due to a previous injury is not very elastic).
  • The elasticity of tendons and ligaments (ligaments do not stretch much, tendons should not stretch at all).
  • The elasticity of skin (skin has some degree of elasticity, but not much).
  • The ability of a muscle to relax and contract to achieve the greatest range of movement.
  • The temperature of the joint and associated tissues (joints and muscles offer better flexibility at body temperatures that are 1 to 2 degrees higher than normal).

External influences

  • The temperature of the place where one is training (a warmer temperature is more conducive to increased flexibility).
  • The time of day (most people are more flexible in the afternoon than in the morning, peaking from about 2:30pm-4pm).
  • The stage in the recovery process of a joint (or muscle) after injury (injured joints and muscles will usually offer less flexibility than healthy ones).
  • Age (pre-adolescents are generally more flexible than adults).
  • Gender (females are generally more flexible than males).
  • One’s ability to perform an exercise (practice makes perfect).
  • One’s commitment to achieving flexibility.
  • The restrictions of any clothing or equipment.

Some sources also suggest that water is an important dietary element regardsflexibility. Increased water intake is believed to contribute to increased mobility, as well as increased total body relaxation.

Rather than discuss each of these factors in significant detail, I will attempt to focus on some of the more common factors which limit one’s flexibility. The most common factors are:

  • Bone structure – Depending on the type of joint involved and its present condition, the bone structure of a joint places very noticeable limits on flexibility. This is a common way in which age can be a factor limiting flexibility since older joints tend not to be as healthy as younger ones.
  • Muscle mass – Muscle mass can be a factor when the muscle is so heavily developed that it interferes with the ability to take the adjacent joints through their complete range of motion (for example, large hamstrings limit the ability to fully bend the knees).
  • Excess fatty tissue – Excess fatty tissue imposes a similar restriction.
  • Connective tissue – Most of “flexibility” work should involve performing exercises designed to reduce the internal resistance offered by soft connective tissues.
  • Physical injury or disability – Most stretching exercises attempt to accomplish this goal and can be performed by almost anyone, regardless of age or gender.

How Connective Tissue Affects Flexibility 

The resistance to lengthening that is offered by a muscle is dependent upon its connective tissues: When the muscle elongates, the surrounding connective tissues become tauter. Also, inactivity of certain muscles or joints can cause chemical changes in connective tissue which restrict flexibility. To quote Michael J Alter directly:

“A question of great interest to all athletes is the relative importance of various tissues in joint stiffness. The joint capsule (i.e., the saclike structure that encloses the ends of bones) and ligaments are the most important factors, accounting for 47 percent of the stiffness, followed by the muscle’s fascia (41 percent), the tendons (10 percent), and skin (2 percent).  However, most efforts to increase flexibility through stretching should be directed to the muscle fascia. The reasons for this are twofold.

  • First, muscle and its fascia have more elastic tissue, so they are more modifiable in terms of reducing resistance to elongation.
  • Second, because ligaments and tendons have less elasticity than fascia, it is undesirable to produce too much slack in them. Overstretching these structures may weaken the integrity of joints.

As a result, an excessive amount of flexibility may destabilize the joints and increase an athlete’s risk of injury.” When connective tissue is overused, the tissue becomes fatigued and may tear, which also limits flexibility. When connective tissue is unused or under used, it provides significant resistance and limits flexibility. The elastin begins to fray and loses some of its elasticity, and the collagen increases in stiffness and in density. Aging has some of the same effects on connective tissue that lack of use has.

How Flexibility Affects Ageing

With appropriate training, flexibility can, and should, be developed at all ages. This does not imply, however, that flexibility can be developed at the same rate by everyone. In general, the older you are, the longer it will take to develop the desired level of flexibility. Hopefully, you’ll be more patient if you’re older.

According to Michael J Alter, the main reason we become less flexible as we get older is a result of certain changes that take place in our connective tissues:

“The primary factor responsible for the decline of flexibility with age is certain changes that occur in the connective tissues of the body. Interestingly, it has been suggested that exercise can delay the loss of flexibility due to the aging process of dehydration. This is based on the notion that stretching stimulates the production or retention of lubricants between the connective tissue fibres, thus preventing the formation of adhesions.”

Michael J Alter further states that some of the physical changes attributed to aging are the following:

  • An increased amount of calcium deposits, adhesions, and cross-links in the body
  • An increase in the level of fragmentation and dehydration
  • Changes in the chemical structure of the tissues.
  • Loss of suppleness due to the replacement of muscle fibres with fatty, collagenous fibres.

This does not mean that you should give up trying to achieve flexibility if you are old or inflexible. It just means that you need to work harder, and more carefully, for a longer period when attempting to increase flexibility. Increases in the ability of muscle tissues and connective tissues to elongate can be achieved at any age.

Strength and Flexibility

One of the best times to stretch is right after a strength workout such as weightlifting. Static stretching of fatigued muscles performed immediately following the exercise(s) that caused the fatigue, helps not only to increase flexibility, but also enhances the promotion of muscular development, and will help decrease the level of post-exercise soreness. Here’s why: After you have used weights (or other stimuli) to overload and fatigue your muscles, your muscles retain a “pump” and are shortened somewhat.

This “shortening” is due mostly to the repetition of intense muscle activity that often only takes the muscle through part of its full range of motion. This “pump” makes the muscle appear bigger. The “pumped” muscle is also full of lactic acid and other by-products from exhaustive exercise. If the muscle is not stretched afterward, it will retain this decreased range of motion and the build-up of lactic acid will cause post-exercise soreness.

Static stretching of the “pumped” muscle helps it to become “looser”, and to “remember” its full range of movement. It also helps to remove lactic acid and other waste-products from the muscle. While it is true that stretching the “pumped” muscle will make it appear visibly smaller, it does not decrease the muscle’s size or inhibit muscle growth. It merely reduces the “tightness” (contraction) of the muscles so that they do not “bulge” as much.

Also, strenuous workouts will often cause damage to the muscle’s connective tissue. The tissue heals in 1 to 2 days, but it is believed that the tissues heal at a shorter length (decreasing muscular development as well as flexibility). To prevent the tissues from healing at a shorter length, physiologists recommend static stretching after strength workouts.

Why Contortionists Should Strengthen

You should be “tempering” (or balancing) your flexibility training with strength training (and vice versa). Do not perform stretching exercises for a given muscle group without also performing strength exercises for that same group of muscles. Judy Alter, in her book Stretch and Strengthen, recommends stretching muscles after performing strength exercises, and performing strength exercises for every muscle you stretch. In other words: “Strengthen what you stretch and stretch what you strengthen!”

The reason for this is that flexibility training on a regular basis causes connective tissues to stretch which in turn causes them to loosen and elongate. When the connective tissue of a muscle is weak, it is more likely to become damaged due to overstretching, or sudden, powerful muscular contractions. The likelihood of such injury can be prevented by strengthening the muscles bound by the connective tissue.

Dynamic strength training consisting of light dynamic exercises with weights (lots of reps, not too much weight), and isometric tension exercises. If you also lift weights, dynamic strength training for a muscle should occur before subjecting that muscle to an intense weightlifting workout. This helps to pre-exhaust the muscle first, making it easier (and faster) to achieve the desired overload in an intense strength workout. Attempting to perform dynamic strength training after an intense weightlifting workout would be largely ineffective.

If you are working on increasing (or maintaining) flexibility, then it is very important that your strength exercises force your muscles to take the joints through their full range of motion. Repeating movements that do not use a full range of motion in the joints (e.g., bicycling, certain techniques of Olympic weightlifting, pushups) can cause a shortening of the muscles surrounding the joints of the working limbs. This shortening is a result of setting the nervous control of length and tension in the muscles at the values repeated most often or most strongly. Stronger stimuli are remembered better.

Over flexibility

It is possible for the muscles of a joint to become too flexible. There is a trade-off between flexibility and stability. The looser you get, the less support offered to the joints by their adjacent muscles. Excessive flexibility can be just as much of a liability as not enough flexibility. Either one increases your risk of injury.

Once a muscle has reached its absolute maximum length, attempting to stretch the muscle further only serves to stretch the ligaments and put undue stress upon the tendons (two things that you do not want to stretch). Ligaments will tear when stretched more than 6% of their normal length. Tendons are not even supposed to be able to lengthen. Even when stretched ligaments and tendons do not tear, loose joints and/or a decrease in the joint’s stability can occur vastly increasing the risk of injury.

Once you have achieved the desired level of flexibility for a muscle or set of muscles and have maintained that level for a solid week, you should discontinue any isometric or PNF stretching of that muscle until some of its flexibility is lost.

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  1. Sport Stretch, by Michael J. Alter.
  2. Stretching Scientifically, by Tom
  3. SynerStretch for Total Body Flexibility, from Health for Life.
  4. The Health for Life Training Advisor, also from Health for Life.
  5. Mobility Training for the Martial Arts, by Tony Gummerson.
  6. Bradford D. Appleton.