Course:KIN366/ConceptLibrary/Flexibliliy

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Movement Experiences for Children
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KIN 366
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Instructor: Dr. Shannon S. D. Bredin
Email: shannon.bredin@ubc.ca
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Definition

Stretching, as it related to physical health and fitness, is the process of placing particular parts of the body into a position that will lengthen, elongate, the muscles and associated soft tissues (Walker, 2007). The process prepares the body for exercise, increases your range of motion and prevents muscle imbalances that can lead to serious injury (Rohmann, 2014). Stretching also helps muscles stay limber after workout, and promotes flexibility and strength. When stretching, muscles are extended to a resistance point and are held there momentarily, which also helps joints by keeping them moving freely (Calvallari, 2015).

Physiology of Stretching

The stretching of a muscle fiber begins with the sarcomere, the basic unit of contraction in the muscle fiber. As the sarcomere contracts, the area of overlap between the thick and thin myofilaments increases. As it stretches, this area of overlap decreases, allowing the muscle fiber to elongate. Once the muscle fiber is at its maximum resting length (all the sarcomeres are fully stretched), additional stretching places force on the surrounding connective. As the tension increases, the collagen fibers in the connective tissue align themselves along the same line of force as the tension. (Appleton, 1995) Thus when you stretch, the muscle fiber is pulled out to its full length sarcomere by sarcomere, and then the connective tissue takes up the remaining slack. When this occurs, it helps to realign any disorganized fibers in the direction of the tension. This realignment is what helps to rehabilitate scarred tissue back to health. When a muscle is stretched, some of its fibers lengthen, but other fibers may remain at rest. The current length of the entire muscle depends upon the number of stretched fibers. The more fibers that are stretched, the greater the length developed by the stretched muscle (Appleton, 1995).

Proprioceptors

Proprioceptors are specialized sensory receptors on nerve endings found in muscles, tendons, joints, and the inner ear. These receptors relay information about motion or position and make us aware of our own body position and movement in space. Proprioceptors detect subtle changes in movement, position, tension, and force, within the bod (Quinn, 2014)

The Stretch Reflex

The stretch reflex; which is also often called the myotatic reflex, knee-jerk reflex, or deep tendon reflex, is a pre-programmed response by the body to a stretch stimulus in the muscle (Walker, 2007). The reflex is designed by the body to prevent muscle tearing and overstress. The stretch reflex is caused by a stretch in the muscle spindle. When the stretch impulse is received a rapid sequence of events follows. The motor neuron is activated and the stretched muscles, and its supporting muscles, are contracted while its antagonist muscles are inhibited. The stretch reflex can be activated by external forces (such as a load placed on the muscle) or internal forces (the motor neurons being stimulated from within) (Walker, 2007).

The Lengthening Reaction

When this tension exceeds a certain threshold, it triggers the lengthening reaction which inhibits the muscles from contracting and causes them to relax. Other names for this reflex are the inverse myotatic reflex, autogenic inhibition, and the clasped-knife reflex (Appleton, 1995).

Reciprocal Reaction

When an agonist contracts, in order to cause the desired motion, it usually forces the antagonists to relax. This phenomenon is called reciprocal inhibition, or sometimes called reciproval innervation because the antagonists are inhibited from contracting (Appleton, 1995).

Importance of Stretching for Children

Normal childhood development is dependent on regular physical activity. Exercise should begin early childhood, along with proper stretching habits. Physical exercise started after adolescence may improve physical condition but may never complete compensate for early neglect. Regular exercise should include methods to increase flexibility. Adequate flexibility is needed for effective movement. Limited flexibility or range of motion prevents participation in exercise, sports, or daily living activities (Heise, 1993). Children who participate in sports or other physically demanding activities need to stretch to prevent injuries. Stretching and warming up are most important during periods of rapid growth, such as during the adolescent growth spurt. (Harris 2014). Furthermore, stretching helps young athletes prevent muscle tears and pulls. Stretching also helps a child’s joints move though a full range of motion. Before stretching, children should do a low-intensity aerobic exercise that should not cause fatigue, such as walking or jumping jacks, as stretching cold muscles can lead to injuries. Stretching after a workout helps avoid stiffness and speeds the recovery of muscles (McLaughlin, 2013).

Types of Stretching

Static Stretching

Static stretching is used to stretch muscles, and is performed by slowly lengthening a muscle to an elongated position, to the point of discomfort not pain (Anderson et al., 1991). The static stretch is held in the fixed position for 15-30 s (Ogura et al., 2007).

Dynamic Stretching

Dynamic stretching uses momentum and active muscle contractions to produce a stretch. Dynamic stretching is comprised of movements that are similar to those in which the participant will engage in (Mann et al., 1999). It is different from ballistic stretching which is repeating small bounces at the end of the range of motion.

Active Stretching

Active stretching is also referred to as static-active stretching. An active stretch is one where an individual assume a position and then hold it there with no assistance other than using the strength of his or her agonist muscles (Appleton, 1995).

Passive Stretching

Passive stretching is also referred to as relaxed stretching, and as static-passive stretching. A passive stretch is one where an individual assumes a position and holds it with some other part of his or her body, or with the assistance of a partner or some other apparatus (Appleton, 1995).

PNF Stretching

PNF (proprioceptive neuromuscular facilitation) stretching is currently the fastest and most effective way known to increase static-passive flexibility. The stretch refers to any of several post-isometric relaxation stretching techniques in which a muscle group is passively stretched, then contracts isometrically against resistance while in the stretched position, and then is passively stretched again through the resulting increased range of motion. PNF stretching usually employs the use of a partner to provide resistance against the isometric contraction and then later to passively take the joint through its increased range of motion. It may be performed, however, without a partner, although it is usually more effective with a partner's assistance (Appleton, 1995).

Isometric Stretching

Isometric stretching is a type of static stretching which involves the resistance of muscle groups through isometric contractions of the stretched muscles. The use of isometric stretching is one of the fastest ways to develop increased static-passive flexibility and is much more effective than either passive stretching or active stretching alone. Isometric stretches also help to develop strength in the "tensed" muscles, and seems to decrease the amount of pain usually associated with stretching (Appleton, 1995).

Ballistic Stretching

Ballistic stretching uses the momentum of a moving body or a limb in an attempt to force it beyond its normal range of motion. This is stretching, or "warming up", by bouncing into a stretched position, using the stretched muscles as a spring which pulls you out of the stretched position. This type of stretching is not considered useful and can lead to injury. It does not allow your muscles to adjust to, and relax in, the stretched position. It may instead cause them to tighten up by repeatedly activating the stretch reflex (Appleton, 1995).

Flexibility

What is Flexibility?

Flexibility is commonly described as the range of motion, or movement, around a particular joint or set of joints (Walker, 2007). It can also be described as how far we can reach, bend or turn. Prominent flexibility leads to less muscle tension and soreness, reduced risk of injury, and increase in relaxation for the mind and body. In addition, inadequate flexibility can affect your athletic performance by preventing you from reaching the full potential, strength and power of your muscles.

Flexibility Types

The term static flexibility refers to an individual's absolute range of motion that can be achieved without movement. In other words, how far we can reach, bend or turn and then hold that position. While the term dynamic flexibility refers to an individual's absolute range of motion that can be achieved with movement. In other words, how far we can reach, bend or turn by using velocity to achieve maximum range of motion (Walker, 2007). Static flexibility is sometimes referred to as passive flexibility, and dynamic flexibility is sometimes referred to as ballistic or functional flexibility.

Range of Motion

Range of motion (ROM) is a term commonly used to refer to the movement of a joint from full flexion to full extension. Exercise physiologist and physical therapists measure range of motion in a joint with an instrument called a goniometer that measures joint range of motion in degrees from the starting position (Quinn, 2014). Range of motion, or range of movement, is so intimately related to flexibility that the terms are often considered having the same meaning. A joint's normal range of motion is determined by what that joint does and how far the bones that comprise it can move. So, range of motion also measures the current amount of motion around a joint as determined by the condition of the bones and the soft tissue surrounding the joint that hold it together (Walker, 2007).

Flexibility Influencing 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 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) (Walker, 2007)

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 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

(Walker, 2014)

The Importance of Stretching

Studies about the benefits of stretching have had mixed results. Some show that stretching helps. Other studies show that stretching before or after exercise has little if any benefit and doesn't reduce muscle soreness after exercise. Studies have shown that static stretching performed immediately before a sprint event may decrease performance to a small degree (Mayo Clinic, 2014).

Benefits

Stretching can help improve flexibility, and, consequently, range of motion in your joints. Better flexibility may improve your performance in physical activities or decrease your risk of injuries by helping your joints move through their full range of motion and enabling your muscles to work most effectively (Mayo Clinic, 2014).

  • Improving athletic performance in some activities
  • Decreasing the risk of activity-based injuries
  • Stress relief by relaxing tight tense muscles that accompany stress
  • Better poster
  • Enhanced coordination

(Inverarity, 2014)

Stretching Technique

It is essential to practice proper stretching techniques. Never push yourself beyond what is comfortable. Only stretch to the point where you can feel tension in your muscles. This way, you will avoid injury and get the maximum benefits from your stretching (Walker, 2014).

  • Warm up first
  • Hold each stretch for at least 30 seconds
  • Don’t bounce
  • Focus on a pain free stretch
  • Relax and breathe freely
  • Stretch both sides
  • Stretch before and after activity

(Inverarity, 2014)


References

Anderson, B., & Burke, E. R. (1991). Scientific medical and practical aspects of stretching. Clinical Sports Medicine, 10, 63-87.

Appleton, B. (1995, January 6). Physiology of Stretching. Retrieved March 1, 2015, from http://web.mit.edu/tkd/stretch/stretching_2.html

Cavallari, D. (2015, February 26). What Is Stretching? Retrieved March 1, 2015, from http://www.wisegeek.org/what-is-stretching.htm

Harris, S. (2014, January 2). Should a child stretch before exercising? Retrieved March 1, 2015, from http://www.pamf.org/sports/harriss/stretch.html

Heise, B. J. (1993). The effect of static stretching on hamstring and lower back flexibility in elementary school children

Inverarity, L. (2014, December 16). Stretching 101: Benefits and Proper Techniques. Retrieved March 1, 2015, from http://physicaltherapy.about.com/od/flexibilityexercises/a/stretchbasics.htm

Mann, D., & Jones, M. (1999). Guidelines to the implementation of a dynamic stretching program. Strength and Conditioning Journal, 21(6), 53-55.

Mayo Clinic. (2014, March 4). Fitness. Retrieved March 1, 2015, from http://www.mayoclinic.org/healthy-living/fitness/in-depth/stretching/art-20047931?pg=1

McLaughlin, M. (2013, October 28). Importance of Stretching for Kids. Retrieved March 1, 2015, from http://www.livestrong.com/article/515934-importance-of-stretching-for-kids/

Ogura, Y., Miyahara, Y., Naito, H., Katamoto, S., & Aoki, J. (2007). Duration of static stretching influences muscle force production in hamstring muscles. Journal of Strength and Conditioning Research, 21(3), 788-792.

Quinn, E. (2014, December 15). Proprioceptors - Glossary of Muscle Anatomy. Retrieved March 1, 2015, from http://sportsmedicine.about.com/od/glossary/g/Proprioceptors.htm

Rohmann, R. (2014, March 13). Stretches Definition. Retrieved March 1, 2015, from http://www.livestrong.com/article/350043-stretches-definition/

Walker, B. (2007, April 2). Stretching and Flexibility Defined. Retrieved March 1, 2015, from http://injuryfix.com/archives/stretching.php