Stretching & PNF – Expanded Study Guide (Deep Dive Version)

This study guide encompasses key concepts and techniques related to stretching and proprioceptive neuromuscular facilitation (PNF) in a concise question-and-answer format, designed for effective exam preparation.

What factors determine flexibility?

Muscle length, joint integrity, and the extensibility of soft tissues.

What is elasticity in stretching physiology?

Elasticity is when tissue returns to its original length after being stretched.

What is the difference between viscoelasticity and plasticity?

Viscoelasticity is tissue that resists stretch initially but elongates gradually, while plasticity is when tissue assumes a new, longer length after the stretch is removed.

What happens to collagen during immobilization?

Collagen becomes weak, disorganized, loses cross-linking, and decreases tensile strength.

What is creep in terms of stretching?

Creep is the gradual elongation of tissue under a constant load.

What is stress-relaxation?

With sustained stretch, the tension decreases over time, requiring less force to maintain the same tissue length.

What sensory receptors are important for PNF effectiveness?

Muscle Spindles and Golgi Tendon Organs.

Why does PNF improve range of motion (ROM) more than static stretching?

PNF reduces muscle resistance through autogenic inhibition and reciprocal inhibition.

What is autogenic inhibition?

When a muscle contracts, GTOs detect the tension and send signals to inhibit the alpha motor neuron, allowing relaxation of the same muscle.

What is reciprocal inhibition?

Activation of an agonist muscle inhibits the antagonist muscle.

When is PNF especially indicated?

When there is tight musculature restricting ROM, during subacute/chronic phases, or when rapid ROM gains are needed.

When should PNF be avoided?

In cases of acute injuries, recent surgeries, severe pain, instability, or contraindications for strong muscle contraction.

What are the steps for the Contract-Relax (CR) technique?

1. Move limb into a comfortable stretch. 2. Patient contracts the muscle for ~5 seconds. 3. Patient relaxes. 4. PTA deepens the stretch.

Why does the Contract-Relax technique work?

The contraction activates the GTO, leading to autogenic inhibition and decreased resistance.

When should Hold-Relax (HR) be used instead of Contract-Relax (CR)?

When joint movement is painful or contraindicated, as HR uses isometric contraction only.

How long should the contraction last in PNF techniques for optimal GTO activation?

Typically 5–10 seconds.

What are the steps for Agonist Contraction (AC)?

1. Bring limb into a mild stretch. 2. Patient contracts the agonist. 3. Increased stretch occurs due to reciprocal inhibition.

When is Agonist Contraction preferred?

When it is painful to contract the tight muscle directly; useful in early rehab.

What is the process of the Contract-Relax-Agonist-Contraction (CRAC) technique?

1. Stretch the tight muscle. 2. Isometric contraction of the tight muscle. 3. Relax. 4. Contract the agonist muscle to deepen the stretch.

What are the clinical applications of the CRAC technique?

Best for significant ROM deficits and when patients can perform active contractions safely.

Why is proper alignment important in stretching?

It ensures that the stretch targets the intended muscle and prevents compensation.

What is needed for stabilization during stretching?

Proximal stabilization anchors the muscle origin and allows isolation of the muscle being stretched.

What determines the ideal intensity of a stretch?

A mild, tolerable stretch that avoids activating the stretch reflex.

How does stretch duration affect stretching outcomes?

Longer durations promote viscoelastic creep and plastic deformation; short holds primarily affect elasticity.

Why should stretching be performed slowly?

Slow application prevents muscle spindle activation and guarding.

Why is frequency important in stretching?

More frequent sessions yield better collagen adaptation than infrequent stretching.

How can stretching gains be reinforced?

By integrating functional tasks and allowing the nervous system to learn the new range of motion.