Definitions of Flexibility and Stability

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Questions and Answers

What does the stability buffer represent in the context of equilibrium?

The total mass of the object

The height of the object's center of mass

The speed at which the object moves

The amount of energy required to destroy equilibrium (correct)

Which factors contribute to the postural stability buffer?

Muscle mass and bone density

Gravity and inertial forces

Base-of-support and stiffness (correct)

Joint laxity and flexibility

Which type of stability is specifically defined as the ability to withstand perturbations while standing still?

Dynamic stability

Joint stability

Ground stability

Postural stability (correct)

What type of stabilization does not require muscular activation?

Passive stabilization Signup and view all the answers

How does joint stability relate to joint laxity?

They are correlated but not 1:1; lax joints can still be stable. Signup and view all the answers

What must typically happen to achieve postural stability in most positions?

Some muscle activation is usually necessary. Signup and view all the answers

What criteria could define joint stability in a mechanical context?

Positional equilibria in no potential degrees of freedom Signup and view all the answers

What does the term 'CoP' stand for in the context of postural stability?

Center of Pressure Signup and view all the answers

What is a consequence of increased stiffness in the physiologic degrees of freedom (DoFs)?

Slower movement and potentially altered coordination Signup and view all the answers

Which statement about joint laxity is accurate?

Joint laxity is typically considered a negative condition. Signup and view all the answers

Which factor is primarily related to health outcomes according to the module?

Stability Signup and view all the answers

What is essential for accuracy in describing range-of-motion in clinical kinesiology?

Recognizing desirable types of joint movement Signup and view all the answers

What should kinesiologists be aware of regarding myths about stretching?

Desirable flexibility and stability are important for health and performance. Signup and view all the answers

What defines a joint as flexible in one degree of freedom (DoF)?

It displays greater than average range of motion Signup and view all the answers

What does 'adequate task flexibility' refer to?

Specific range of motion needed for a target task Signup and view all the answers

Which of the following is an example of a multi-articular link?

A muscle that spans multiple joints Signup and view all the answers

What is meant by 'passive sufficiency of links'?

Sufficient length of links to not restrict passive joint motion Signup and view all the answers

Which statement is true regarding flexibility definitions?

A whole chain is flexible if most of its DoFs are flexible. Signup and view all the answers

In which sport would overall flexibility be most critical?

Diving Signup and view all the answers

What is a common tensile constraint of motion?

Muscles Signup and view all the answers

Which of the following does NOT typically limit passive motion?

Muscles Signup and view all the answers

What is the characteristic of static stretching in terms of velocity?

Typically reached slowly Signup and view all the answers

Which type of stretch involves both internal (active) and external (passive) forces at the end-range?

Resist-Relax / PNF Signup and view all the answers

What is the typical duration for holding static stretches?

5-60 seconds Signup and view all the answers

Which type of stretching is characterized by fleeting movements at the end-range?

Ballistic stretch Signup and view all the answers

How is the lengthening force generated in dynamic stretching?

By both antagonist and external forces Signup and view all the answers

What is the primary characteristic of ballistic stretching regarding intensity and resistance?

Typically higher intensity with active resistance Signup and view all the answers

In terms of resistance, how does static stretching mainly operate?

Only passive resistance Signup and view all the answers

What type of stretching typically allows for varying intensity of stretching forces?

Dynamic stretch Signup and view all the answers

What is a characteristic of short-term mechanical effects of stretching?

Temporary lengthening of muscles Signup and view all the answers

What potential long-term effect can occur as a result of regular stretching?

Mobilization of passive multi-articular links Signup and view all the answers

What happens to the tolerance of stretching during short-term stretching sessions?

Tolerance increases with repetition Signup and view all the answers

Which outcome is NOT commonly associated with chronic long-term stretching according to available studies?

Improved muscle stiffness Signup and view all the answers

What is the expected effect on resting length and stiffness after short-term visco-elastic stretching?

No change in resting length or stiffness Signup and view all the answers

What is a notable short-term perceptual effect of stretching?

Increased tolerance to tension Signup and view all the answers

According to studies on stretching, what type of stretching is associated with improvements in ankle dorsiflexion range of motion?

Chronic long-term stretching Signup and view all the answers

What is the primary effect of short-term stretching on lumbar flexion range of motion demonstrated in studies?

Transient increase in range with prolonged stretching Signup and view all the answers

Study Notes

Flexibility Definitions

Flexibility can be defined in various ways, including statistical flexibility, adequate task flexibility, passive sufficiency of multi-articular links, and generalized hypermobility/laxity.
Statistical flexibility refers to a joint having a range of motion (RoM) greater than the average for that joint.
Adequate task flexibility refers to the necessary RoM for a specific task, which varies depending on the activity.
Passive sufficiency of multi-articular links implies the links are long enough to not restrict passive motion of any joints they span.

Multi-Articular Links

Multi-articular links, such as muscles, ligaments, fascia, nerves, and vessels, span multiple joints and influence motion.

Passive Sufficiency

Passive sufficiency refers to the sufficient length of multi-articular links to not restrict passive motion across the joints they span.

Stability

Postural stability is the ability to resist external perturbations without collapsing.
Joint stability is the stability of positional equilibria in non-physiologic degrees of freedom (DoFs), and it is correlated with joint laxity, but not directly proportional.

Stabilization

Passive stabilization: Results from forces and moments that do not require muscle activation, including gravity, inertia, tissue elasticity, and viscosity.
Active stabilization: Involves muscle activation to maintain postural or joint equilibria, typically necessary for most positions and for maintaining stability in lax joints.

Stretch Types

Static stretch: Held at the end of the range of motion (RoM) with a relatively low force over a period of time.
Dynamic stretch: Involves movement through the RoM with variable force and velocity.
Ballistic stretch: Rapid, forceful movements through the RoM, typically at a higher force and velocity.
PNF (Proprioceptive Neuromuscular Facilitation) stretch: Involves a combination of active and passive stretching techniques.

Mechanical and Perceptual Effects of Stretching

Short-Term Stretching: Causes temporary lengthening of tissues through viscoelastic stretching, increasing tolerance of tension but with no lasting effects on resting length or stiffness.
Long-Term Stretching: May lead to an increase in RoM, likely due to increased tolerance of tension rather than structural changes in muscle tissue.

Costs of Active Stabilization

Stiffness: Increased metabolic work, slower movement, and altered coordination.
Compression: Possible damage to hyaline cartilage and intervertebral discs, and constraint of breathing if not trained.

Summary

Range of motion (RoM): The extent of joint movement in a specific direction.
Laxity: The amount of movement in a joint that is not considered normal or healthy.
Flexibility is defined as the ability of a joint or muscle to move through its full range of motion, encompassing statistical flexibility, task-specific adequacy, and passive sufficiency.
Equilibrium and stability are critical for optimal health and performance, and understanding the relationship between flexibility, laxity, and stability is crucial for developing effective exercise strategies for health and performance improvement.

Key Points

Desirable flexibility and stability are interrelated and have different implications for health and performance.
Flexibility is primarily related to performance (with some implications for health), while stability is primarily related to health (injury prevention) with some implications for performance.
It is essential to understand the different stretch types and their effects to develop effective strategies for achieving desirable ranges of motion for optimal health and performance.

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Description

This quiz explores various definitions of flexibility, including statistical flexibility, adequate task flexibility, and passive sufficiency of multi-articular links. Additionally, it touches on the concept of postural stability and its importance in resisting external forces. Test your knowledge on these fundamental concepts in biomechanics.