Some Truths and Speculations About Stretching
We hear terms like, “I haven’t touched my toes since I was a kid,” or, “I know I need to stretch more.”
It seems that the general public has acclaimed flexibility as a gold standard of movement wellness and this may be true. However, there is a large misunderstanding about what flexibility actually is and what role it holds for the musculoskeletal system.
What is Flexibility?
Operationally defined, it is the quality of bending easily without breaking. Note the word bending. It does not say stretch or elongate, but bend. Flexibility is likely more about a composite of joint mobility. Therefore, flexibility has wrongly become a synonym for stretching as these two terms are actually different.
So What is Stretching?
Operationally defined, it causes (something) to become longer or wider by pulling it. This is often what we are considering or imagining as we try to touch our toes or stretch our chest.
Does Stretching Work?
It depends, but usually not. If stretching really worked the way we think it does, patients/clients that have been stretching every day for weeks, months, or even years, wouldn’t STILL BE TIGHT! So, maybe we should be thankful it doesn’t work like we think because we would be very unstable humans due to joint laxity. So what is true about stretching?
Muscles don’t get longer when we stretch. The gold standard research articles state prolonged stretching adds sarcomeres in series, or end-to-end, but what isn’t conveyed to the public is that the average sarcomere length is reduced, leaving no change in overall muscle length.
Stretching is more related to perception and tolerance. When a muscle is stretched we stop because we feel a noxious stimulus in the muscle. This signals the brain to guard against further motion in order to protect the muscle from damage. When we see improvements over time, it is more likely that we have improved our tolerance to stretching. Improved tolerance means less of a threat and more tissue length expression not longer muscles.
What I Speculate:
Stretching works at the level of the nervous system via noxious stimuli. When the human body experiences noxious stimuli there becomes an increase in sympathetics (fight or flight) throughout the body. This actually increases system rigidity and limits motion. Our brain’s perception is that we don’t have much mobility. However when we stop we tend to feel “better” or “loose”, due to the withdrawal of the sympathetic input (noxious stimulus). Thus there becomes a relative increase in parasympathetic activity (rest and digest) and we feel more mobile. ***Interesting note: the same effects happen if we focus on breathing mechanics!
Concentric (short) and Eccentric (long) muscles can both produce a tension sensation due to fluid dynamics. Concentric musculature will be high pressure, low volume and eccentric musculature will be low pressure, high volume. Based on the concentric/eccentric model there needs to be a gradient created across a space. If we can’t do this appropriately there may be a perception of tightness when moving. This may be why an 80 year old feels tight just like the 16 year old gymnast does. Don’t believe me? Take a listen to the Master Jeidi himself, Bill Hartman, and what he has to say about stretching based on this model.
So to recap:
Flexibility and stretching are different.
Muscles don’t get longer with stretching, but our tolerance to the activity may improve.
We feel better after stretching due to nervous system shifts.
Recapturing mobility in the system relies on the ability to concentrically orientate eccentric musculature and eccentrically orientate concentric musculature.