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 activites 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 is the ability to perform dynamic movements of the muscles to bring a limb through its full range of motion in the joints.
Static active flexibility is the ability to assume and maintain extended position 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 (other than from your own leg muscles.)
Static passive flexibility (also called passive flexibility) is the ability to assume extended position and then maintain them using only your weight, the support of your limbs, or some other apparatus. The ability to maintain the position does not come solely from your muscles as it does wit static-active flexitbility. 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 develp than passive flexibility (which is what more people think of as “flexibility”); not only does active flexibility require passive flexibility in order to assume an initial extended position, it also requires muscle strength to be able to hold and maintain that position.
According to Gummerson, flexibility (he uses the term mobility) is affected by the following factors:
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 and tendons should not stretch at all)
The elasticity of skin (skin actually 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)
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 a lesser degree of 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 a particular 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 with regard to flexibility. Increased water intake is believed to contribute to increased mobility, as well as increased total body relaxation.
I will attemp to focus on some of the more common factors which limit one’s flexibiliity. According to Syner Stretch, the most common factors are: bone structure, muscle mass, excess fatty tissue, and connective tissue (and of course, physical injury or disability.)
Depending on the type of joint involved and its present condition (is it healthy?) the bone structure of a particular 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 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 (i.e. large hamstrings limit the ability to fully bend the knees.) Excess fatty tissue imposes a similar restriction.
The majority of “flexibility” work should involve performing exercises designed to reduce the internal resistance offered by soft connective tissues. Most stretching exercises attempt to accomplish this goal and can be performed by almost anyone, regardless of age or gender.
The resistance to lengthening that is offered by a muscle is dependent upon its connective tissues. When the muscle elongates, the surrounding connective tissues beome more taut. Also, inactivity of certain muscles or joints can cause chemical changes in connective tissue which restrict flexibility. According to M. Alter, each type of tissue plays a certain role in joint stiffness, “The joint capsule (i.e. the saclike structure that encloses the ends of bones) and ligments 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.)”
Mr. Alter goes on to say that the efforts to increase flexibility should be directed at the muscle’s fascia. This is because it has the most elastic tissue and because ligaments and tendons (since they have less elastic tissue) are not intended to be stretched very much at all. Overstretching them may weaken the joint’s integrity and cause destabilization (which increases the 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 elasticy, and the collagen increases in stiffness and in density. Aging has some of the same effects on connective tissue that lack of use have.
With appropriate training, flexibility can, and should be develped 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 will be more patient if you’re older.
According to Mr. 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. As we age, our bodies gradually dehydrate to some extent. It is believed that “stretching stimulates the production or retention of lubricants between the connective tissue fibers, thus preventing the formation of adhesions.” Hence, exercise can delay some of the loss of flexibility that occurs due to the aging process.
Mr. 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 fibers with fatty, collagenous fibers
This doesn’t mean that you should give up trying to achieve flexibility if you are old or inflexibile. It just means that you need to work harder, and more carefully, for a longer period of time when attempting to increase flexibility. Increases in the ability of muscle tissues and connective tissues to elongate (stretch) can be achieved at any age.