Flexibility and Muscle Length Assessment

Dynamic Flexibility

The muscles ability to contract through the available ROM which is Directly Related to function

Passive Flexibility

The ability of the joint or series of joints to be moved through its available ROM, directly related to the extensibility of soft tissues that cross the joints

Is Normal joint ROM an absolute requirement?

No it is not a requirement but it is important for successful functional activities

What is the goal of flexibility?

Our goal is optimization of motion- with decreased Risk of Breakdown

Hypermobility Definition

lengthening muscle and joints well beyond their "normal" or expected ROM

If static and dynamic supporting structures lack control during functional activities, what does this lead to?

Instability

Joint instability may predispose a person to what?

pain or musculoskeletal injury (form vs. force closure)

Hypomobility Definition

Decreased or restricted motion of single or multiple joints

What can Hypomobility lead to?

compensatory motion and if its prolonged hypomobility it can lead to contracture formation

What is the difference between contracture and hypomobility or tightness?

Contracture is used more with greater range of motion loss and tightness and hypomobility are used more in a clinical setting to describe mild shortening with muscular tightness

Contracture Definition

adaptive shortening of the muscle- tendon unit and other soft tissues that cross or surround a joint

What does a contracture cause?

significant loss of active and passive ROM

How do contractures develop?

Develop due to loss of tissue elasticity due to prolonged joint positioning

Causes for a contracture

Musculotendinous, Central Nervous System tells muscles to contract when they dont need to, or for joint/ connective tissue specific reasons

What is non-contractile connective tissue composed of?

collagen, elastin, reticulin, and ground substance

Non-contractile Collagen fibers properties

Responsible for the strength and stiffness of tissue and resist tensile deformation

Non-contractile Elastin fibers properties

Provide extensibility (flexible) and show a great deal of elongation during small load - failure occurs abruptly with high loads

Non-contractile Reticulum fibers properties

provide tissue with bulk and structure

Non-contractile Ground substance properties

an organic gel that helps stabilize collagen networks and resist compressive forces

Non-contractile more general properties- When do collagen fibers fail?

failure of collagen tissue occurs at ~10%

Non-contractile more general properties- When does elastin fail?

Could lengthen to 150% without failure

Is collagen tissue or elastin stronger?

Collagen is 5x stronger than elastin

Tissues that can tolerate high tensile loads are high in...

collagen fibers

Tissues that tolerate greater compressive loads or high in...

ground substance

Tendon fibers orientation

Collagen fibers that are parallel and can resist greatest tensile load and aligned in series to transit forces of bone

Ligaments, Joint Capsules, and Fascia Fiber Orientation

Resist multi-directional forces- ligaments that resist major joint stress have a more parallel orientation

Skin Fiber Orientation

Oriented randomly so they are limited in resisting high levels of tension

What is muscle tissue composed of?

Both non-contractile and contractile tissue

Non-contractile components of muscle tissue

Endomysium, Perimysium, and Epimysium

Endomysium

innermost layer that separates individual muscle fibers

Perimysium

encases fiber bundles

Epimysium

the outermost layer that encases the entire muscle

Individual muscle are composed of what?

many muscle fibers that lie in parallel with one another

A single muscle fiber is made up of many what?

myofibrils

What is each myofibril composed of?

even smaller structures called sarcomeres (in series)

What are sarcomeres (contractile units) composed of?

Overlapping myofilaments of actin and myosin proteins

What do sarcomeres allow the muscle to do?

contract and relax

What does prolonged immobilization without active muscle contraction result in?

Decay in contractile protein, Decreased muscle fibers diameter, and number of myofibrils and intramuscular capillary density which ultimately leads to atrophy and weakness

What muscle fibers does atrophy occur more quickly and more extensively in?

tonic muscle fibers (think abs) in comparison to phasic fast twitch fibers

What does atrophy usually begin with?

a few days of immobilization

What would be the response to immobilization in a shortened position?

In several weeks there is a reduction in muscle length, and number of sarcomeres due to sarcomere absorption

What would be the response to immobilization in a lengthened position?

surgical intervention to improve overall outcomes

What graph best represents the mechanical behavior of connective tissue?

Stress-strain curve

What type of load do collagen fibers elongate with?

an externally applied load

What happens to collagen fibers as tension increases?

they continue to lengthen and fibers straighten - it will continue to increase fiber strain until a point where bonds break

What does stress refer to in the stress strain curve?

force per unit area

What does strain refer to in the stress strain curve?

the amount of deformation or lengthening that occurs when theres an external load

Where is our muscle length test assessed?

R1 - end of the toe region

What is the toe region of the stress strain curve?

The first response to loading which is the straightening and aligning of collagen and occurs with minimally applied force

What is the elastic range of the stress strain curve?

Stress and strain have a direct relationship and stress beyond the toe region aligns fibers in the direction of applied force

What is the goal of the intervention in stress strain curve?

Intervention at or beyond the elastic limit because this is where change can happen

What is the plastic range in stress strain curve?

Strain that continues past the elastic limit to the point of rupture or failure and tissues strained into this region will have permanent deformation after the external load is released

What do the X and X' represent in the stress strain curve?

They represent continued improvement in muscle length therefore X' represents a new toe region and X represents a new elastic range which causes plastic range to shrink

What is considered a Grade 1 Ligament Strain?

Microfailure: rupture of some fibers after deformation into early part of the plastic range

What is considered a Grade 2 Ligament Strain?

Macrofailure: rupture of an increased number of fibers and partial failure after deformation into the later part of the plastic range

What is considered a Grade 3 Ligament Strain?

Complete rupture or tissue failure after deformation beyond the plastic range

Tissue Creep

Low intensity loads applied for long durations increase connective tissue deformation and allow gradual rearrangement of collagen fiber bonds (Remodeling)

What does the amount of tissue deformation in creep depend on?

the amount of force and the duration that the force is applied for

Stress-Relaxation

A load applied with the tissue kept at a constant length results in decreased internal tension (Stress) in the tissue until equilibrium is reached - frequency of stretching helps improve success

What is one variable that affects tissue deformation?

Rate dependence - the speed at which force is applied affects how the tissue responds

How does rapid force application affect the stress-strain curve?

It produces a steeper stress-strain curve compared to a slowly applied force ( frankenstein stretch)

Why does a rapid stress response protect tissue?

It keeps deformation below the plastic range, reducing the risk of tissue failure ( frankenstein stretch)

How do dynamic warm-ups influence tissue deformation?

They prepare tissue for activity by improving its ability to handle stress and strain.

In lab, what are factors that limit flexibility?

one vs two joint muscles and capsular restrictions

Which of the following muscles is placed under MOST passive tension,when the hip is extended and knee flexed?

Rectus femoris

Which position of the pelvis will place more tension on the rectus femoris?

Posterior pelvic tilt

Does posterior or anterior pelvic tilt place more tension on the hamstring at rest?

anterior pelvic tilt

Which of the following muscles is placed under the MOST passive tension, with Right cervical side bending, and left cervical rotation?

Left upper trapezius

What is the start position for the TRI hip test?

Patient able to achieve 0° hip extension, 70-80° knee flexion, and remain in the sagittal plane (0° abduction).

TRI hip test — if the patient achieves the start position, what does that mean?

Test is negative.

If the patient does NOT achieve the start position, what is the next step?

Extend the knee and check if hip extension increases.

TRI hip test — knee extension improves hip extension to ≥ 0° → what does this indicate?

(+) Rectus femoris length test.

TRI hip test — knee extension improves hip extension but still < 0° → what does this indicate?

(+) Rectus femoris length test.

TRI hip test — if knee extension does NOT improve hip extension, what is the next step?

Abduct the hip and check if hip extension increases.

Abducting hip improves hip extension to ≥ 0° → what does this indicate?

(+) Tensor fascia latae (TFL) length test.

Abducting hip improves hip extension but still < 0° → what does this indicate?

(+) TFL and iliopsoas/hip joint capsule length test.

What is the function of the piriformis at 0°-60° of hip flexion?

External rotation of the hip.

What is the function of the piriformis at 60°-90° of hip flexion?

Hip abduction

What is the function of the piriformis at 90°+ of hip flexion?

Internal rotation of the hip

Why is it important to know how piriformis function changes with hip flexion angle?

To differentiate between muscular restriction (piriformis/ERs) and capsuloligamentous restriction when assessing hip ROM.