Do This Routine to Burn up to 1.5x More Fat on Leg Day | Thomas DeLauer
Do This Routine to Burn up to 1.5x More Fat on Leg Day – Thomas DeLauer
Proprioceptive neuromuscular facilitation (PNF), also known as PNF Stretching, is a more advanced form of flexibility training, which involves both the stretching and contracting of the muscle group being targeted
One of the most effective forms of stretching for improving flexibility and increasing range of motion – the main goal of PNF is to increase range of motion and performance
Myotatic Reflex
Also known as the stretch reflex, is a pre-programmed response by the body to a stretch stimulus in the muscle
When a muscle spindle is stretched an impulse is immediately sent to the spinal cord and a response to contract the muscle is received
Since the impulse only has to go to the spinal cord and back, not all the way to the brain, it is a very quick impulse – generally occurs within 1-2 milliseconds
The stretch reflex is designed as a protective measure for the muscles, to prevent tearing.
The entire muscle is fully relaxed before repeating the process
*Research has concluded that the best time to hold the stretch is 6 seconds, and performance increases when done at least twice a week*
Benefits
Increases range of motion (ROM), flexibility, muscular strength has been shown to increase, increase stride rate & length (in jogging), increase vertical jump
Note:
Athletic performance is generally found to decrease when PNF stretching is performed before exercise, and increase when performed independent of exercise, or after exercise was completed
*Performance decreases when maximal muscle effort is required such as during sprinting, plyometrics, cutting, weight-lifting and other high intensity exercises
Mechanisms
4 theoretical physiological mechanisms for increasing ROM have been identified: autogenic inhibition, reciprocal inhibition, stress relaxation, and the gate control theory
Each of these theoretical mechanisms are reflexes that occur when the Golgi tendon organs (GTOs) in the tendons of the TM, or in the antagonist muscle to the TM, detect harmful stimuli (such as a stretching sensation or during a contraction)
Autogenic Inhibition
what occurs in a contracted or stretched muscle in the form of a decrease in the excitability because of inhibitory signals sent from the GTOs of the same muscle
Reciprocal Inhibition
Reciprocal inhibition is what occurs in the TM when the opposing muscle is contracted voluntarily in the form of decreased neural activity in the TM. It occurs when an opposing muscle is contracted in order to maximize its contraction force, in this case, the TM relaxes.
Stress Relaxation
Stress relaxation is what occurs when the musculotendinous unit (MTU), which involves the muscles and the connected tendons, is under a constant stress
Both muscles and tendons have viscoelastic properties in which they exhibit characteristics of both viscous and elastic materials
A viscoelastic material both resists shear flow and strain linearly when stress is applied and returns to the original form once the stress is removed from the MTU. As what was mentioned before, when the MTU falls under a constant stretch, a phenomenon known as “stress relaxation” occurs
This decreases the force generated by the viscous material when it resists the elongation stimulus that stretching causes within the MTU. Because the viscous material loses its ability to resist the stretch over time, the MTU slowly increases in length, a property that is referred to as “creep” of the MTU
The Gate Control Theory
The gate control theory is what occurs when two kinds of stimuli, such as pain and pressure, activate their respective receptors at the same time
References
1) Proprioceptive Neuromuscular Facilitation (PNF): Its Mechanisms and Effects on Range of Motion and Muscular Function. (n.d.). Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3588663/
2) Quinn, E. (2015, January 14). Get More From Your Post-Exercise With PNF Stretching. Retrieved from https://www.verywellfit.com/postexercise-stretching-is-pnf-right-for-you-3120290
3) Understanding the Stretch Reflex (or Myotatic Reflex). (2016, October 6). Retrieved from https://stretchcoach.com/articles/myotatic-stretch-reflex/
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