Stretch Exercises
Stretching can be defined as movements performed with the primary goal of improving muscle extensibility and joint ROM
To live is to move. We must have mobility to jump, play, fight, dance, run, speak, write, and even breathe.
Human mobility is limited by the available range of motion (ROM) at the synovial joints1. ROM is limited by 2 main ways: Joint stiffness and Muscle tension1.
Muscle Tightness
Muscle tension can be divided into 2 forms of tension: active and passive1.
Passive Tension
Passive tension is generated through the structural components of the muscle tissue and surrounding fascia1. This is akin to a rubberband being pulled apart and it resists the stretch due to its elasticity.
Passive tension is undetectable by EMG.
This type of muscular tightness would be due to long term postural adaptations or scarring after an injury1.
Clinically, this would be described as:
- Adhesions
Active Tension
Active tension refers to muscle tension due to its neuroreflexive properties causing active contraction of the muscle1.
Neuroreflexive muscle activation refers to excitation of motor γ-efferents and α-efferent activation1.
This type of tension would be described clinically as:
- Spasms
- Guarding
- Contraction
Joint stiffness
Intra vs extra-articular
Stretching
Stretching is based on the theory that if we bring a muscle to a lengthened position it will have short term increases in tension, but long term decrease in tension.
Types of Stretches
- Static: Specific position is held to the point of muscle tension and stretching sensation
- Dynamic:
- Pre-Contraction:
Static stretches
Static stretches can be subdivided into passive (partner assisted) or active (self-stretch).
Dynamic Stretching
- Active stretch
- Ballistic stretch
Active Stretching
Active Stretching: A form of dynamic stretching characterized by moving a limb through its available ROM to end range repeatedly1
Ballistic Stretching
Ballistic Stretching: A form of dynamic stretching characterized by rapid, alternating movements at end-range of motion1.
Due to injury risk, Ballistic Stretching is no longer recommended1.
Pre-Contraction Stretching
Pre-Contraction Stretching: Refers to a form of stretching where a muscular contraction precedes the stretch1. This muscular contraction can be in the agonist or antagonist muscle1.
- PNF techniques
- Contract-relax (CR)
- Hold-relax (HR)
- Contract-relax Agonist-contract (CRAC)
- Post-isometric relaxation (PIR)
- Post-facilitation stretching
- Medical Exercise Therapy (MET)
Contract-relax Stretch (CR)
Contract-relax: Refers to a form pre-contraction stretching where a muscle is contracted following its spiral-diagonal PNF pattern, followed by stretch1.
Hold-relax (HR)
Hold-relax: Refers to a form pre-contraction stretching where a muscle is contracted through its rotational component of the PNF pattern, followed by stretch1.
Contract-relax Agonist-contract (CRAC)
Contract-relax Agonist-contract: Refers to a form pre-contraction stretching where a muscle contracts following its spiral-diagonal PNF pattern, followed by contraction of the antagonist muscles to stretch the target muscle1.
Post-isometric relaxation (PIR)
Post-isometric relaxation: Refers to a form pre-contraction stretching where a muscle performs a mild isometric contraction followed by a stretch1.
- 25% muscle contraction1
Post-facilitation stretching
Post-facilitation stretching: Refers to a form pre-contraction stretching involving maximal muscle contraction at mid-range followed by a rapid movement to end-range followed by a static stretch1.
Medical Exercise Therapy (MET)
Acute Physiological effects
There are many theories as to why there is an improvement of ROM after stretching:
Static Stretching Dosage
Pre-Contraction Stretching Dosage
Contraction of a muscle prior to stretching the muscle can effectively increase ROM1.
Maximal &asmp; submaximal contractions: Maximal and submaximal contractions are equally effective1.
There is evidence that this type of stretching may have purely neurologic effects since patients have displayed bilateral ROM improvements following a unilateral stretch1.
There are many theories as to why this neurological phenomenon exists.
Many speculate that the muscle relaxes due to autogenic-inhibition where a muscle experiences an inhibitory refractory period post-contraction1.
EMG studies have demonstrated that muscle activation remains largely the same or increases post-contraction, which contradicts the theories that ROM improvements following pre-contraction stretches are due to decreased muscle excitation1.
Stretch-induced Strength Loss
Do NOT perform static stretches before athletic activity, it can lead to decreases in muscle strength, running performance, and jumping performance known as “stretch-induced strength loss”1.
Maximal contraction of the target muscle before a static stretch may decrease stretch-induced strength loss1.