PNF

Question 1

What are muscle spindles and what do they do?

Answer 1

Muscle spindles lie between skeletal muscle fibers and provide excitatory signals to the CNS about how far and fast a muscle is being stretched. The CNS then sends an impulse back causing the muscle to contract (stretch reflex) to prevent overstretching.

Question 2

What are Golgi Tendon Organs (GTOs) and where are they located?

Answer 2

GTOs are located in the musculotendinous junction and are activated when there is an increase in muscle tension from over-contraction. They send inhibitory signals to the brain.

Question 3

Define active insufficiency.

Answer 3

Occurs when a muscle is at its shortest possible length and generates little active tension due to excessive overlap of the contraction sites.

Question 4

Define passive insufficiency.

Answer 4

Occurs when a muscle is at its longest possible length and is unable to generate sufficient tension because the contraction sites are too far apart.

Question 5

Give an example of passive insufficiency.

Answer 5

When testing rhomboids and middle traps: externally rotating the GH joint lengthens the rhomboids, making them passively insufficient compared to middle traps.

Question 6

What is creep in muscle tissue?

Answer 6

A time-dependent deformation due to viscoelastic properties in response to a constant load.

Question 7

What is active inhibition?

Answer 7

Inhibition of a muscle by its own activity (autogenic) or that of its antagonist (reciprocal) via GTO and/or muscle spindle activation.

Question 8

What is autogenic inhibition?

Answer 8

Also known as inverse stretch reflex or antimyotatic reflex. It occurs when the target muscle contracts voluntarily, then relaxes, allowing GTOs to send inhibitory signals reducing excitability and enabling elongation.

Question 9

What is reciprocal inhibition?

Answer 9

Occurs when the opposing muscle contracts, causing relaxation of the target muscle, allowing elongation.

Question 10

What does PNF stand for, and what does it do?

Answer 10

Proprioceptive Neuromuscular Facilitation stretching integrates voluntary contractions to improve muscle elasticity, making it effective for short-term gains in ROM.

Question 11

What is the current theory behind PNF stretching?

Answer 11

It involves sensorimotor processing, viscoelastic adaptations, and changes in patient’s stretch tolerance (creep).

Question 12

Who should not use PNF techniques?

Answer 12

Patients with paralysis, spasticity, hematomas, recent fractures, inflammatory arthritis, hypermobility, or when contractures are needed for joint stability.

Question 13

When is PNF indicated?

Answer 13

To increase AROM, PROM, strength, stability, neuromuscular control, controlled mobility, and muscle firing re-education.

Question 14

How do you perform the Hold-Relax technique?

Answer 14

1. Lengthen target muscle (first barrier) – hold 30s
2. Isometric contraction at 50% strength for 5–10s
3. Relax, then passively move to new range – hold 10s
4. Repeat 3×

Question 15

When should Hold-Relax be used?

Answer 15

When mobility/stability are pain-free, contraction is pain-free, and goal is to inhibit the target muscle.

Question 16

What type of inhibition is used in Hold-Relax?

Answer 16

Autogenic inhibition

Question 17

How do you perform Contract-Relax technique?

Answer 17

1. Lengthen target muscle (first barrier) – hold 30s
2. Isotonic contraction at 50% strength for 5–10s
3. Relax, then passively move to new range – hold 10s
4. Repeat 3×

Question 18

When should CR be used?

Answer 18

Same as HR: when mobility/stability are pain-free, and the goal is to inhibit the target muscle.

Question 19

What type of inhibition is used in CR?

Answer 19

Autogenic inhibition

Question 20

How is CRAC performed?

Answer 20

1. Stretch target muscle to first barrier – hold 30s
2. Isometric or isotonic contraction of target muscle for 5–10s
3. Concentric contraction of opposing muscle into new range
4. Repeat 3×

Question 21

When is CRAC used?

Answer 21

Same indications as HR and CR, but both muscles must contract pain-free. It’s the most effective PNF for ROM gains.

Question 22

What type of inhibition is used in CRAC?

Answer 22

Both autogenic and reciprocal inhibition

Question 23

What is the process for Agonist Contraction (aka AIS)?

Answer 23

1. Start in neutral
2. Concentric contraction of opposite muscle – hold 2–5s
3. Release and return to start
4. Repeat 10×

Question 24

When is AC indicated?

Answer 24

For muscle guarding, weak target muscle, and to initiate neuromuscular control. Less effective with normal flexibility.

Question 25

What type of inhibition is used in AC?

Answer 25

Reciprocal inhibition

Question 26

How is Reciprocal Inhibition performed for muscle spasms?

Answer 26

1. Target muscle in end range 2. Isotonic or isometric contraction of opposing muscle 3. Patient actively moves into new range 4. Repeat until spasm subsides Avoid passive lengthening of spastic muscle

Question 27

How do you perform a Partner Contract-Relax-Contract stretch for the left hamstring?

Answer 27

1. Supine, leg on therapist shoulder – hold 30s 2. Patient isometrically contracts hamstrings – 10s, 50% strength 3. Patient actively moves into new range 4. Repeat 3×

Question 28

How do you reduce upper trapezius tone using PIR?

Answer 28

1. Palpate trap resting tone 2. Stretch to first barrier – hold 30s 3. Patient contracts traps – 5s, 10% 4. Patient actively lengthens 5. Repeat 3× – reassess