Kind of a weird question right? We understand what the word means, we can even demonstrate it quite easily, and we know it feels pretty damn good…
But can you actually describe it?
It’s kind of baffling huh?
Well let’s take a good look at stretching today then! We’re going to look at:
- Local Components of Stretch
- Neuromuscular Components of Stretching
- Active vs Passive Stretching: Stretching with Intention
Local Components of Stretching
The simplest way to describe stretching is:
Lengthening one joint away from another joint.
Of course things are never quite that simple, lets delve deeper.
Stretching is a viscoelastic process. Meaning it kind of works like both honey, and a rubber band.
- Honey is a viscous fluid, when held in a spoon it will slowly form to the shape of the spoon, and then maybe extend beyond. Meaning it will resist deformation (won’t extend past the confines of the spoon) until gravity, or the strain (too much honey) pushes it over the edge.
- Rubber bands are elastic, they will stretch and then recover back to their original shape when you let go of them
Ligaments and tendons combine both of these properties. They resist deformation and they are capable of recovering back to their original shape, all in due time.
Collagen and Elastin are the two components that determine the viscoelasticity of the tissue. We all have these in our ligaments, tendons, muscles, fascia, etc. It’s important to note though that they can decrease with age.
Those are the components of a ligament/tendon. With that knowledge we can start to look at what happens locally, or around the joint, when you stretch them.
Here are some stretching facts:
- Repetitive stretching studies have shown that the most deformation occurs on the 1st stretch. After 4 stretches there was a very minimal change in length.
- It takes about 20-30 seconds to reach muscle relaxation, so there’s no need to hold a stretch longer than 30 seconds (if your intention is to lengthen a muscle, more on this concept later)
- Slowly moving into a stretch is much more beneficial than quickly stretching especially for Passive Stretching (more on this later too)
- Once elongated length changes are not rapidly reversible due to the viscous nature of your connective tissue. (25 mins usually results in 50% recovery, and up to 24-48 hours for 100% recovery)
Woah, pretty interesting right?
This is your Brain on Stretching:
This next bit of information blew my mind when I first learned it:
Most of the length achieved from stretching is from your brain, not from the local tissue.
Yup, reread that again and then maybe a 3rd time because it’s true. Your brain ultimately governs your ROM or Range Of Motion.
Some cars have a Governor that limits the amount of top speed the car can achieve. Your brain works similarly with your joints. Your body can move in a whole lot of different ways, but that doesn’t mean that it should.
Stability is your body’s ability to control or limit motion. When the brain feels it needs to stabilize a joint, it will lock down the range of motion to limit the amount of motion it can achieve.
Usually it imposes these ROM limits to keep you safe and out of harm. Over time these can be detrimental because having a full healthy ROM is vastly important to your overall health. Here’s an article that shows how a simple sitting test can determine how long you’ll live, all based around the mobility of your hip.
What I’ve outline here describes the Theory of Sensation (in regards to stretching)
The reviewers concluded that stretching increases flexibility (i.e. joint ROM) by altering the sensation of stretching such that stretch tolerance or the onset of pain occur at greater joint angles. They concluded that stretching does not change the actual mechanical properties of muscle or the point at which the stretch reflex is activated. Covered in much more detail here
In a nutshell: stretching increases your ROM by decreasing the amount of pain and the feeling of increasing muscle length each time you stretch. There was no actual change to the muscle, your brain adapted to the feeling of stretch and allowed you to go further because it was desensitized each time.
Facts on the Neuromuscular component of stretching:
- Spindle Receptors in the muscles signal to the brain the current length of a muscle and the rate at which it’s lengthening during a stretch. If the stretch is too quick the brain can signal a reflex contraction to limit the amount of stretch.
- Golgi Tendon Organs (GTOs) in the muscles report tension to the brain. These trigger if the stretch is sustained longer than 6 seconds or if the muscle forcefully contracts.
- Reciprocal Inhibition: When one muscle contracts, it’s opposing muscle relaxes. (Ex: if the Quads contract to straighten the knee, the hamstrings will relax to allow that to happen)
- When you stretch you signal to the brain to increase the ROM at the local joint (or release some of its governance on the joint).
- ROM will usually decrease about 2 hours after you do a bunch of stretching. (After your next yoga class note how stiff your body will start to feel about 2 hours after class)
- This is because if you are not actively using that new ROM granted by your brain it will regovern the joint and the local tissue will recover back to where it started (that elastic component of the viscoelastic segment above)
- If you want to actually increase and sustain ROM you have to do active muscle exercises (like lifting weights, etc) at that new Range of Motion. Utilizing the new the ROM signals the brain that it’s beneficial to keep that increase. It also creates a local increase in the amount of collagen and cross links to strengthen the local area.
- Some suggest that stretching every 4 hours helps keep and maintain ROM as well.
There is a lot more to stretching than you thought
Stretching With Intention: Dynamic vs Passive Stretching
Let’s recap really quick because you just got a landslide of information on stretching.
- Stretching occurs both locally and neurologically
- The brain limits the range of motion of your joints to keep you safe and stable, stretching allows for an increase in range of motion
- On a local level stretching slightly deforms our ligaments and tendons, and over time allows them to elastically return back to normal.
Another, more advanced way, to describe stretching is the application of force, or a load, over time creating strain on these structures.
Here are the different types:
- Passive Stretching: Sustaining/relaxing into a position, this usually relies on gravity to accomplish the stretch.
- There is also no/minimal muscle activation which imposes greater load on the ligaments and tendons.
- Usually allows for a greater ROM because the muscles are not active and limiting.
- Dynamic/Active Stretching: actively contracting a muscle to accomplish lengthening another muscle.
- Usually features a decreased ROM, but activates more muscles for greater stability.
From a performance standpoint, active stretching has no detriments to performance and strength. Passive stretching, however, can reduce performance by 4.2 ± 5.0% for 1-2 mins of passive stretching and 7.0 ± 5.7% for over 2 mins. (From Systematic Reviews detailed here)
Moral of that story:
Don’t fail your body during your workout:
Dynamic stretch before working out, static stretch after
In a usual yoga/exercise setting we engage in a lot of active stretching. Restorative Yoga and Yin Yoga are where you start to see more Passive Stretching.
Passive stretching is also why many of us have postural problems.
- Since we sustain positions, usually hunched over and internally rotated, in our daily lives we impose gravitational stress on inactivated joints over long periods of time.
- We also lack movement every 20 or so minutes that would allow our ligaments and tendons time to recover back to their original shape and strength.
In the biomechanics world we call this phenomenon: Creep. Or tissue deformation over time.
As you now know it doesn’t take long for Creep to occur too. After about 8 sections the GTOs or tension receptors fire, after about 30 seconds the muscle completely relaxes and after that most of the force is directed into your tendons and ligaments.
Luckily your body can recover from this, but it takes a good amount of time.
In a human in vivo study, following 20 minutes of deep flexion, a 25-minute rest period was required in order to achieve 50% recovery and a 50-minute rest period was required to achieve 70% recovery from the resulting creep. Recent evidence demonstrate that both creep and tension-relaxation induced in 20-50 minutes of loading or stretching a ligament, respectively, demonstrated 40-60% recovery in the first hour of rest, whereas full recovery is a very slow process which may require 24-48 hours.
(Solomonow, M. Ligaments: A source of musculoskeletal disorders. Anatomy, physiology, pathophysiology review. Journal of Bodywork and Movement Therapies 2009 (13):136-154.) Summary accessed here.
It’s important to note that these times of recovery also increase with age!
In the world of yoga that we live in it’s quite a common place to hold a posture passively for a while, especially in Yin and Restorative style classes.
Knowing what you now know,
Do you think it’s responsible to hold a passive spinal flexion position for very long?
My answer is a very hard no, you honestly shouldn’t sustain a Forward Fold for longer than 1-2 mins TOPS. (Especially if you’re twisting too: Spinal flexion with rotation is the most dangerous position for your spinal discs [like in 1/2 Dragonfly pose])
If you answered yes or are still unsure, consider this:
You’ve creeped this person’s or your own ligaments into further flexion. During their recovery time are they likely to sustain spinal flexion again? Uhhhhh yes!
- They’re going to round over their phone the moment they plug back in after class.
- They’re also going to round over a steering wheel when they drive away.
- Plus, I wouldn’t be surprised if they go home and plop down on a couch and further their flexion there.
Can you see the pattern?
We are constantly sustaining spinal flexion, which offers close to no recovery time for our connective tissue. The moment you do recover, chances are you round forward again for a sustained amount of time and begin the vicious cycle all over again.
It’s suspected that spinal flexion creep is the reason behind a lot of mechanical back pain. The ligaments in the front of the spine are lax, and in the back are taught or overstretched. Over time this causes nerve impingement and even spinal disc protrusions because the spine is not ever able to recover back to normal alignment.
Moral of that story:
Open up, it feels really good! Here’s a poem I wrote:
Extension, extension, extension…
aka Creep with Intention 😉
The Home Stretch
At this point I wouldn’t be surprised if your brain is feeling a bit on the over stretched side. Mine is, just from researching and writing this article XD
The stuff I wish to leave you with:
- Stretching is a brain & body experience. I’m on the side of the fence that believes it’s more brain controlled ROM oriented than actual mechanical muscle changes. (I do believe both occur for the record, the brain is the way bigger player in my opinion)
- Dynamic/Actively Stretch when you warm up. Static/Passive stretch when you cool down. Work out efficiently, try not to hinder yourself before you even start!
- Static stretch with intention! Don’t be the creep who creeps your body/class into too much of a bad forward fold internally rotated position!
To actively apply what you learned here, do some Creep with Intention based yoga:
- Supported Bridge – picture here, I’ll be posting a breakdown on this pose in the very near future.
- Supported Bound Angle – picture here, I’ll also be posting a nice breakdown for this one as well
- Supported Forward Fold – use a chair, or a lot of props to keep your spine straight and upward to get the same benefits, rather than spinally flex forward.
Hold these for about 5 minutes a piece and you’ll be feeling divine in no time!
Further stretch your brain with some similar articles to this one:
- Fascia: Better your understanding of connective tissue
- Yoga Injuries: Sleeping/Half Pigeon Part I: The Anatomy: See how this common Western passive stretch can be affecting your body in not so great ways
- Anatomy of a Modern Day Human: Troll Posture: More on forward folded and internally rotated posture with an emphasis on the neck and thoracic spine
Tune back in later this week as I plan on giving you a great breakdown on Supported Bridge and Bound Angle!
Don’t be the wrong type of creep!
References (not provided in text):
- Johnson, Jim Bulletproof Your Shoulder Dog Ear Publishing, 2014.