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HOME CONTENT PREPARATION ANALYSIS DESIGN APPENDICES GLOSSARY
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SECTION II - ANALYSIS
LESSON 6 - FLEXIBILITY
LESSON 7 - ENDURANCE
LESSON 8 - STRENGTH
LESSON 9 - SKILL
LESSON LESSON 11 - ENERGY LESSON 12 - NUTRITION LESSON 13 - STRATEGY
ANALYSIS OF FLEXIBILITY
Flexibility: Effective Ranges of Motion in Joints
Objectives
Upon completion of Lesson 6 you should be able to demonstrate the following objectives:
v Write an acceptable definition of flexibility.
v Write
a list of stretching exercises that may be used to maintain or improve range of
motion in the major joints of the body.
v Demonstrate
how to measure the range of motion existing in the joints of the body.
v Describe the benefits of maintaining or improving flexibility
v Identify
the joint actions of the following regions of the body: neck, shoulder girdle,
shoulder, elbow, lower back, hip, knee, and ankle.
Along with strength and endurance, flexibility (range of motion in joints) is also an important component of muscle fitness. This lesson will focus on the meaning of flexibility, the joint movements, and structural limits of joints. When ligaments and tendons are too lax, the results can include instability and risk of dislocation and other injuries. Too little flexibility is far more common than too much, however, both extremes, being too flexible and not being flexible enough, are not good.
When stretching, which improves flexibility, is a regular part of a fitness-training program, it contributes to improved posture, better body balance and performance, and an enhanced sense of well being. Although it is often overlooked or misused, it is a critical factor in achieving peak physical potential. Studies have shown that injuries occur as a result of tight or stiff muscles. Therefore, flexibility with its many benefits should be included in all fitness-training programs.
Perhaps the most important knowledge to be gained from the study of flexibility in the body is that which allows one to identify flexibility exercises that need to be included in a fitness training program. The basis of this knowledge is the ability to identify joints and joint actions according to particular skills needed for a given activity. For instance, the ability to serve a tennis ball requires a full ROM or flexibility in the shoulder girdle, shoulder, and arm making the serve. Limitation caused by either of the joints involved will limit one's ability to develop a powerful serve. Having this knowledge makes it easy for a tennis player to learn which exercises are needed to stretch the muscles of the shoulder girdle, shoulder, and arm.
Additionally, it is important to know that there are three types of stretching exercises that can be used to maintain and improve flexibility, each of which possesses unique benefits for sports performance. The three forms of stretching exercises are static, ballistic, and proprioceptive neuromuscular facilitation. Static stretching is the safest and most commonly used method of stretching. It offers the least risk of injury during stretch-training exercises. Ballistic stretching is more suited for developing flexibility for explosive movements, such as punting a football, but exposes a person to greater risk of injury during stretch-training exercises. PNF is the most effective method of stretching to improve flexibility, but it requires assistance from a person who is knowledgeable of the correct procedures to follow. All three of these methods of flexibility training may be used exclusively or in combination to develop a successful flexibility training program.
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Flexibility is the ability of a joint to move freely in every direction or, more specifically, through a full and normal range of motion (ROM), according to its potential. Within each joint there is a range of motion that is optimal and for each activity in which a joint is used there is an optimum ROM needed to achieve peak performance. The optimum ROM is determined by and varies with the activities selected. No matter what the activity may be, there are factors which can limit joint ROM or mobility: genetic inheritance; joint structure; connective tissue elasticity within muscles, tendons or other soft tissue around a joint; strength of the muscle group opposing the actions of another muscle group (ROM of flexor muscles versus ROM of extensor muscles); and neuromuscular coordination.
To improve performance or posture, flexibility training should be directed toward overcoming the factors that limit ROM by emphasizing balance of muscle groups of a particular joint, not over stretching the movement limiting connective tissues . Although, flexibility is a valuable aspect of training, it is important for exercisers to be aware of the potential disadvantages associated with over training or excessive flexibility. The goal of a stretch training program should be a well-balanced selection of flexibility improvement exercises that are combined with strength improvement exercises to achieve greater joint stability with optimal ROM for particular activities or skills.
An understanding of movements or joint actions is necessary for anyone desiring to become fully knowledgeable of flexibility. To achieve this knowledge, joint structure, stretch reflex, joint movements and exercise implications of the upper extremities, and joint movements and exercise implications of the lower extremities must be considered. Knowledge in these four areas of concern is the first step toward gaining mastery of concepts essential to an understanding of flexibility training.
Flexibility exercises should be designed or selected to increase the range of motion in a specific area, such as the low back, the knee, or the shoulder girdle. However, to achieve these goals the structural factors, which limit flexibility, must be considered:
1) the elastic limits of the ligaments and tendons crossing a joint,
2) the elasticity of the muscle tissue itself,
3) the way bones and joints connect, and
4) the skin.
All of these factors must be carefully evaluated as a flexibility training program is carried out to determine the actions that are possible in a joint, and to provide guidance during each attempt to improve ROM. Without such concern, there is a potential for overstretching.
Two principal areas of the body may be used to divide the different joints, muscles and connective tissues influencing ROM. Flexibility in both of these divisions of the body determine or influence how well people can move in sport activities and the joints needing attention in a flexibility training program. The first area of concern is the muscle and joint movements of the upper body. The upper body muscles include movements of the head and neck, shoulders, upper back, chest, elbows, wrists, and hands and fingers. The ability of these joints to move freely is vital to the success of quality movements. The lack of full ROM in these joints, during physical activity, increases the potential for poor performance or inability to perform. For instance, violin players must be able to hyper extend the wrist joint (move back of hand backward toward the forearm) to finger the strings over various positions of the violin finger board. The inability to hyper extend the wrist will limit or prevent proper placement of the fingers on the violin and subsequently either limit or prevent playing.
The muscles, tendons, bones, ligaments, and other connective tissues forming the joints of the neck (cervical vertebra) are structured to make it possible for the head to move in many directions. This joint allows the head to be turned from left to right, while facing forward (rotation), moved forward, upright, and backward (flexion, extension, and hyper extension), tilted sideward and upright to the right and left shoulders (lateral flexion and medial extension), and moved through all of these positions in a circular motion (circumduction). Flexibility of these joint movements are important for balance. The absence of a full ROM in either movement will cause one's balance to be affected.
The muscles, tendons, bones, ligaments, and other connective tissues forming the joints of the shoulder girdle are also structured to allow movement in many directions. The shoulders can be raised upward (elevation), pushed downward (depression), pushed forward (protraction), and pulled backward (retraction), in accordance with the movement of the scapula and the clavicle. The shoulder girdle can also be moved through all of these position in a circular motion. These joint movements are essential for swinging, reaching, pushing, and pulling motions. A presentation of all major joint actions are available in tables such as the one below to simplify the concept of joint actions.
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Joint actions of the Shoulder Girdle
| Action | Selected Exercises | Muscle |
|
Upper: elevation of scapula Middle: adduction of scapula Lower: depression of scapula |
Upright rowing, shoulder shrugs with resistance |
Trapezius |
| Elevation of scapula | Shoulder shrugs with resistance | Levator Scapular |
| Adduction and elevation of scapula | Chin-ups, supported dumbbell bent over rows | Rhomboid Major and Minor |
The muscles, tendons, bones, ligaments, and other connective tissues forming the shoulder, the joint formed by the connection of the upper arms to the shoulder girdle, permits the movement in many directions. The arm can be moved forward and upward (flexion), downward and backward (extension and hyperextension), sideward and away from the body (abduction), inward to the sides of the body (adduction), turned inward (inward rotation), turned outward (outward rotation), and rotated in a circular motion (circumduction). Additionally, the arm can be moved diagonally away from and toward the body (diagonal abductionand diagonal adduction). These joint actions are included in many activities.
The muscles, tendons, bones, ligaments, and other connective tissues forming the joints of the arm permits movement at the elbow, wrist, hands, and fingers. At the elbow joint there are four movements possible: the elbow can be bent (flexion), straightened (extension), and the forearm rotated inward (pronation) and rotated outward (supination). Some activities require substantial flexibility in the wrists and fingers, which includes bending the wrist or fingers (flexion) and straightening them (extension and hyperextension), bending the wrist sideward and toward the forearm on the thumb side (radial deviation), bending the wrist sideward and toward the forearm on the little finger side (ulna deviation), spreading the fingers apart (abduction), and holding them together (adduction). Normal flexibility, which permits a full ROM in all joint, is essential for good performance. But in certain activities there may be a need for specific joints to have more than normal flexibility. When this need occurs, the joints in question must be emphasized in flexibility training. And, when this need is not met there may be physical limitations in activities of interest. For instance, an activity that requires more than normal flexibility in the wrists and fingers is playing the piano. The lack of flexibility in the these joints will prevent a piano player from voicing certain chords or using various techniques that they are expected to perform.
The second division of the body to consider, regarding flexibility, is the muscle and joint movements of the back and lower body. The lower body motions includes movements of the lower back, pelvis, hips, knee, and ankle. The muscles, tendons, bones, ligaments, and other connective tissues responsible for these joints permit single and multiple actions. So, if you want to know what flexibility exercises to practice, the only thing needed is an understanding of the joint and joint actions that are involved in the movement of interest to you.
When joints are stretched, there is a stretch reflex. This reflex is caused by a nerve signal from either the muscle spindles or the Golgi tendon organs. The muscle spindles are located in muscles and lie parallel to the muscle fiber. In general this structure moves when the muscle fibers move. So if a muscle fiber is stretched, so is the spindle. The spindle responds to the velocity of the stretch. This means that if the muscle is stretched quickly and extreme enough, the muscle spindle sends a message to the spinal cord, which then returns an order to create a sudden protective muscle contraction. This shortening effect occurs to prevent potential tissue damage. The spindle ceases to fire when the shortening begins. An example of muscle spindles at work can be observed when someone falls asleep in a seated position. As the head relaxes and bends forward, the muscle spindle experiences a sudden stretch. This results in the muscle spindles sending a message to the cervical muscle fibers to cause sudden contractions, which is revealed by a sudden jerk of the head to the upright position. It is important to note that as the stretch reflex occurs, contraction of the muscles responsible for the opposing actions are inhibited. For instance, if the quadriceps are stimulated to extend a leg, as a result of the stretch reflex of muscle spindles, the opposing muscles, which are the hamstrings, are inhibited from contracting to bend the leg. This action is called reciprocal inhibition.
The reflex contraction caused by muscle spindles is proportional to the intensity of the stretch up to a point. That is, up to the point that a muscle begins to tear, the reflex contraction may continue, then suddenly stop, so that the muscle relaxes. This relaxation response to extreme stretch is called autogenic inhibition and is dependent on the Golgi tendon organs (GTO). Golgi tendon organs are located in the tendons of muscle. However, unlike spindles, which are sensitive to the stretch of muscles, they are sensitive to the stretch of tendons, during intense contractions of muscles. When the tendon stretch is sensed, information is sent to the central nervous system to cause the contracted muscle to relax. In other words, spindles cause muscles to contract to prevent them from being over stretched, and Golgi tendon organs cause muscles to relax to prevent them from being over contracted. Both muscle stretch and tendon stretch are voluntary actions, but the stretch reflex caused by these movements are automatic functions that exist to prevent damage to muscle fibers
An example of the tendon organs in actions can be demonstrated by arm-wrestling. It has been suggested that the loss of the contest occurs when the tendon organ inhibition overcomes the voluntary effort to maintain contraction.. additionally, the breaking point in muscle strength testing is believed to be related to inhibition caused by the sensitivity of the Golgi tendon organs to the intense contraction.
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In flexibility testing there is no single test that can be used to predict ROM in other joints. Therefore, each joint must be measured individually with specifically designed tests. The purpose of this lesson is to illustrate how joints are measured; it is not the intent of this lesson to explain multiple joint measurements throughout the body. The joints covered are the shoulder, trunk, and hip.
The measurement of shoulder flexibility is directed toward testing the multi-rotational components of the shoulder and whether it is good, fair, or poor. This test involves determining how well a person can get both hands to touch behind his or her back. The person should sit or stand in an upright position and attempt to bend one elbow so that the hand goes over the shoulder and comes to rest with the palm facing the back. Then, the person should bend the elbow of the other arm at his or her side so that the hand goes behind the back with the palm facing away from the back. With both hands behind the back, the person should move the hands so that the fingers touch. The results may be interpreted as follows: if the fingers touch, the flexibility is good; if the fingers are not touching, but are less than two inches apart, the flexibility is fair; and if the fingers are more than two inches apart, the flexibility is poor.
The trunk extension test is used to evaluate the amount of backward bend in the lower back (lumbar spine). Loss of flexibility in this area of the back increases the risk injury and low back pain. Trunk extension is tested by lying face down with both hands in position for push-ups. Then, push the upper body upward while holding the lower back relaxed as much as possible with the hip bones in contact with the floor. The movement is stopped when the hip bones begin to lose contact with the floor. Trunk extension is evaluated by the following standards: if the hips remain in contact with the floor while the arms are fully extended, extension of the lower back is good; if the hips rise from the ground up to two inches, extension of the lower back is fair; and if the hip rise from the ground two inches or more, extension of the lower back is poor. The opposite of extension is flexion, so it is also important to test for hip flexion. Hip flexion tests are done to evaluate ROM in the hips and the degree of hamstring tightness. This is done by lying flat on the back and having one leg held down while the other is lifted with the knee extended to a position of 80 to 85 degrees from the horizontal. Normal ROM will allow for this amount of hip flexion and reduce the risk of low back pain and injury. Hip flexion can be evaluated by this standard: tight hamstrings and other limitations to a normal range of motion is indicated if a leg is raised to a position that is less than 80 degrees from the horizontal. Hip flexion should also be done without pain in the back of the leg or the bending of the knee. To test for hip flexion length, the same starting position is held; a leg is grasped behind the knee and pulled toward the chest. Normal length is revealed when the other leg stays straight and flat on the surface. If the leg raises off of the surface when the other leg is pulled to the chest, short hip flexor length is indicated.
There are many tests required to measure ROM in joints. In fact there are as many tests as there are joints in the body. It is unlikely that a person will have time to stretch all joints in a flexibility training program. Therefore, to determine which tests should be selected, it is necessary to identify the joint actions of the skills performed or needed. On the basis of this observation, flexibility exercises should be selected and may be used to ensure the ROM desired. If the appropriate joint actions can be identified in a particular movement or skill, the flexibility exercises needed to address the joints involved can be properly selected. This approach represents the principle of specificity.
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Although flexibility is important for everyone, it is especially important for male and female sports enthusiasts. Regular stretching routines will maintain or improve flexibility, good range of motion. It will also support healthy, natural, and functional posture and contribute to improvements in strength. When properly managed, regular flexibility training reduces risk of injury to muscle, tendons, and ligaments. Although, too little flexibility is far more common than too much, both can lead to injury. Therefore, it is important to achieve the desired level of range of motion in joints, according to the specific activities involved. When this goal is achieved, performance is enhanced and the risk of injury is minimized.
Stretching and deep breathing are important parts of the warm-up and the cool-down. When you warm up a light stretch prepares the body for exercise. After a workout, a more demanding stretching routine can be used to cool the body down.
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Flexibility or the ability to move the body joints through a maximum range of motion without undue strain is specific to given joints and particular sports or physical activities. It is primarily dependent on the soft tissues of joints (ligaments, tendons, and muscles) and less dependent on the bony structures of joints. However, the bony structures of certain joints do limit flexibility. For example, hyperextension of the spinal column is limited by the position and shape of the vertebrae of the back (spinous process).
There are three types of stretching exercises that may be used to maintain or improve range of motion in the joints of the body: static stretching, ballistic stretching, and proprioceptive neuromuscular facilitation (PNF, stretching with the assistance of a knowledgeable partner). Each of these methods of stretching may be used to improve range of motion in joints, which can be evaluated by specific tests. Progress in the improvement or maintenance of flexibility can be determined by the specific movements for each joint. The assessment of the tests are based on measurement of the degrees of movement in a joint, which is reported as being good, fair, or poor, according to norms that have been established. Higher levels of performance and benefits are achieved by persons who posses ranges of motion that is greater than or equivalent to the desired norms. A test for measuring the range of motion in the shoulder joint involves raising an arm with the elbow extended from a horizontal position to a position above the shoulder slightly pass the side of the face ( 95 degrees), then, lowering the arm from the horizontal position down and backward to a position behind the body (150 degrees). This range of motion in the shoulder joint is an enabling factor for the development of a powerful tennis serve.
A full range of motion in the joints of the body offers benefits other than improved potential for performance. When properly managed, regular flexibility training reduces risk of injury to muscle, tendons, and ligaments, supports healthy, natural, and functional posture, and contributes to improvements in strength.
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Engebretson, B. G. "Effect of an Active-Inhibition Stretching Protocol on Delayed-Onset Muscle Soreness." Physical Therapy, Vol. 79, Issue 5, May 1999.
Knudson, Duane. "Stretching during Warm-Up: Do We Have Enough Evidence?" JOPERD - The Journal of Physical Education, Recreation, and Dance, Vol 70, Issue 7, September 1999.
American Council On Exercise. Personal Trainer Manual. American Council On Exercise. San Diego, CA. 1999.
Arnheim DD, Printice WE. Principles of Athletic Training, 10th ed. McGraw-Hill Division, 1999.
McArdle, W. D., Katch, F. I.., and Katch, V. L (1991). Exercise Physiology: Energy, Nutrition, and Human Performance. Lea & Febiger, Malvern, PA.
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