October 18, 2023 • 51 mins
In this third episode in our Becoming an Evidence Informed Yin Teacher or Student, I'll be reviewing some actual papers for you that are not directly about Yin Yoga but instead about an important component of our practice, stretching.
In this third episode in our Becoming an Evidence Informed Yin Teacher or Student, I'll be reviewing some actual papers for you that are not directly about Yin Yoga but instead about an important component of our practice, stretching.
I'll demystify the effects of stretching on muscle hypertrophy and performance. And address the common belief that pain is always a result of tightness. We'll shed some light on the connection between static stretching and heavy resistance training. All by reviewing a selection of studies, highlighting the role and benefits of stretch training in reducing muscle loss, stimulating muscle growth, and enhancing strength and performance.
But there's more to stretching than meets the eye. We'll explore how it can mitigate inflammation and aid in tendon repair. We'll discuss the challenge of measuring tension and strain, the impact of resistance training on tendon stretching, and the value of referencing research in yoga teaching.
To keep the conversation going, join us on our Facebook group 'Movement for Healing'.
And don't forget to tune in next week as we dive into topics like nervous system regulation, mindfulness, and their role in pain care.
Become an evidence informed Yin teacher or student, enroll in my Yin Yoga Teacher Training Module I: https://yoga.mandyryle.com/yin-teacher-training-module-i/
Join the conversation in my FREE Facebook group, Movement for Healing https://www.facebook.com/groups/710104050217437/
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:00):
Welcome to the Yin Yoga Podcast.
I'm your host, mandy Ryle, andI am so excited for the third in
our series Becoming anEvidence-Informed Yin Yoga
Teacher or Student.
As promised, today, I will bereviewing some interesting
evidence for you so that you canstart to see, number one, how
(00:24):
you put what you have beenlearning actually into the
process of reading andprocessing research.
Number two, so you can see howresearch literacy directly
impacts you as a teacher or apractitioner of Yin.
And then, finally, so that youcan increase your body of
(00:46):
knowledge around something soessential to our practice that
would be stretching.
There is a pervasive myth inour practice that stretching is
just for gaining range of motion, and I am going to present some
(01:07):
evidence for you in thisepisode which will help you to
see all of the wonderful thingsthat happen as a result of
stretching, and I really hopethat you can bring this into
your teaching or into yourpractice immediately.
I'm going to let you know alsothat I am providing the full
text links for every singlepiece of research that I will be
(01:31):
discussing in this episode.
However, my show notes do notallow enough room for me to put
all of those full text linksinto the podcast players, so
here's what I'll do.
Instead, I'm going to inviteyou to please join my Facebook
group.
It's a private group calledMovement for Healing.
(01:53):
Once approved in that group,you will see each of the full
text links for the articles, andyou will also have an
opportunity to ask any follow upquestions that you might have
or to add any comments that youwould like to add.
I will leave a link to theMovement for Healing Facebook
(02:17):
group in the show notes, or youcan just head right to Facebook
and type it in.
Thank you so much for yourinterest in research literacy.
Here is episode number three.
So, as you know, this is thethird episode in my series
(02:45):
Becoming an Evidence-InformedYoung Teacher or Student.
Right here at the outset, Iwant to let you know that there
will be one more episode in thisseries, where I'll be reviewing
evidence related to the nervoussystem and cognitive benefits
of the practice of Yen, and I'llespecially like to highlight
(03:08):
how Yen can contribute to a paincare process, because that is,
after all, my personal specialty.
Today, though, we're going tobe looking at how stretching
specifically influences tissues,and I chose the three studies
that I'll be discussing in thisepisode because they illuminate
(03:31):
some outcomes of practice, someconsequences of stretching that
I do not think are widely knownor certainly understood by our
industry, yen Yoga and Yoga ingeneral.
So I am very excited to tellyou this information, because I
(03:52):
think it's really going tobroaden your horizon and your
love and awe for what we areactually doing in our practice.
So before we dive in, though, Iwant to make sure that you
understand that reading one ortwo or three studies, or even
(04:12):
six studies, is not reallyenough to truly be an expert on
a topic.
I mean, think about it.
There is a reason that researchmust be duplicated by multiple
organizations and differentscientists before it's actually
considered conclusive, right?
So when a new interestingconclusion comes up in a piece
(04:34):
of research, the next step isfor somebody else to try to
duplicate those results.
And for the same reason, it'simportant that we don't limit
our knowledge to just one study,but that we instead have a
broad range of research that wecan draw from.
So a lot of times, we sort ofuse evidence as like a blunt
(04:57):
instrument to confirm our bias.
We essentially would likecherry pick some evidence so
that we can back up what we'retrying to say, the point we're
trying to make.
But there is a better way touse evidence.
I think that a better strategyis to use evidence to contribute
(05:21):
to your personal body ofknowledge so that you can
continue to develop your ownskills.
A big part of this iscontinually challenging your own
biases and assumptions.
If you find a study thathappened 20 years ago and you're
like this is great.
This is everything that I'vebeen saying.
(05:42):
I highly recommend that youmake sure that you look at more
recent evidence as well, becauseoften you will find that there
is some contradiction, somedevelopment, as maybe methods or
technologies have advanced.
Becoming a really trulywonderful evidence informed
(06:06):
teacher will require quite a bitof humility, and in fact, I
think that's probably true forany profession, not just yoga
teachers and yen teachersspecifically.
So that is a little bittroublesome because if you're
just starting out in yourresearch literacy journey,
(06:30):
you're going to have to startwith one or two or three or six
studies.
Right, and that's okay.
It just means that you'rebuilding up your body of
knowledge over time and you willaccumulate knowledge that can
help you to serve yourpopulation of students better or
to customize your personalpractice to become even more
(06:50):
effective.
That can happen in one or twoor three studies.
So I say this also to let youknow that the studies that I'm
going to discuss here are just afraction of the research that
has helped me to form my ownopinions and to develop specific
teaching protocols orstrategies.
Okay, I am not setting the holygrail by these particular
(07:13):
studies, okay.
So before we get startedlooking specifically at the
research, I wanted to kind ofback up and bring this to more
of a practical realm, becausewhat I've noticed about training
yoga teachers all these yearsis that we really do best when
we know how this is going to beapplied specifically to our
(07:37):
practice or to our teaching.
So let me help you toconceptualize how you will apply
your new research literacy thatyou've been building over these
last few weeks.
For the most part, yourstudents won't really see a huge
(07:58):
difference in your teaching,right?
They won't understand that whatthey see is just the very tip
of the iceberg and that yourbody of knowledge and your skill
and your wisdom is like therest of the iceberg that's under
the ocean, right?
Massive amounts of informationthat you have to bring to bear
(08:20):
at any given moment in theteaching experience or in a
learning experience, buthopefully your students will
feel the difference in theresults that they're getting.
I know that we like to talkabout non ambition and practice
and indeed that is importantwhen you're in a practice
experience but we need to berealistic here.
(08:42):
People come to yoga becausethey're looking for a result.
That's the only reason anyonedoes anything right.
So, regardless of what thatresult is, my assumption is that
you can probably find evidenceto help you, to help your
students to get to that resultmore efficiently, more quickly,
(09:03):
more completely.
To be evidence informed willinfluence your, your post
choices, your sequencing.
It's going to impact yourtheming and that's gonna be much
more important in next week'sepisode.
It's going to impact your handson assisting and perhaps most
(09:25):
importantly I believe, it'sgoing to impact the language
that you use, the words that youchoose.
So let's just start with thatone the language.
How is your languagepotentially going to change as a
result of being evidenceinformed?
I'm gonna go out on a limb hereand say that the first thing is
(09:46):
you might avoid results-basedlanguage that would indicate
that a quote stretch end quotecould permanently lengthen
tissues.
So we might not make claimslike that anymore that Yin yoga
makes you more flexible becausethe tissues are lengthening.
(10:06):
You'll understand more aboutthat as we go today.
You might instead focus onother benefits of the poses and
you will have the information toback that up.
Another thing that might happento your language is you might
reduce your language around thedanger or safety of poses.
(10:29):
I would say that's probably thebiggest difference that it's
made in my teaching and if thathas piqued your interest, that
you might change your thinkingor language around danger or
safety of poses.
Make sure that you tune into theepisode next week because
that's gonna be the lion's shareof what we're gonna talk about,
(10:51):
because I think it's so, soimportant.
So if you are not currentlysubscribed to the podcast,
quickly, just scroll up, hitthat subscribe.
Some podcast apps also allowyou to opt in to alerts.
Make sure that you have optedinto those because I don't want
you to miss that.
That one is incrediblyimportant for you, for your
(11:12):
students, for our profession.
So how could being evidenceinformed potentially change your
pose choices?
Once evidence informed, I thinkthat you will understand that
more intensity to a stretch willnot change the length of
muscles, so you might start toavoid some of the more gnarly
(11:34):
difficult, harrowing poses,understanding that results can
happen with a much smaller levelof intensity.
Here's another thing that mightchange your pose choices is if
you understand that pain is notthe result of tightness.
(11:55):
Pain is not the result oftightness.
I just literally obliterated asacred cow just now.
I know we're gonna be doing alot of that in this episode.
So once you understand thatpain is not the result of
tightness, you might start toavoid prescribing or teaching
specific stretches for thatpurpose, and I know as a yoga
(12:22):
teacher myself, as a trainer ofteachers, people are asking us
all the time for a pose tostretch X, y or Z because it
hurts.
So perhaps being evidenceinformed could help you to give
more helpful, beneficialsuggestions to your students and
(12:44):
could potentially help you tobe empowered to address the true
driver of tightness andsensitivity, which is the
nervous system.
We're gonna talk more aboutthat next week.
Being evidence informed, youwill likely develop strategies
for helping to your students toembrace their range of motion,
(13:09):
and you will do this because youwill understand that range of
motion is largely a product ofgenetics and bone morphology and
that no amount of stretchingcan change those.
So perhaps being evidenceinformed will help you to
support students in working,accepting, being content with
(13:30):
the body that they have.
So, as I said, I'm gonna besticking today with research
that specifically addresses howduration stretching impacts
tissues.
And let me give a littledisclaimer here Research rarely
gives us an ironclad conclusion.
(13:51):
Most of the time, it raisesmore questions, right, it's sort
of like, okay, we got thisresult, but now we don't really
know why.
Now we need to look at that.
We have more questions than wehad when we started.
But what research does do is itmoves us slowly, inexorably,
over time toward more effectivestrategies.
(14:14):
It gives us more what, how,when, and that can be incredibly
useful to a yoga professionaland, I believe, to someone who
simply loves the practice of theend.
So the reason I chose this firststudy is because it lays a few
sacred cows in the yin world.
(14:35):
Now I don't wanna come in andjust steal your lollipop, but as
a teacher, my mission is I amcommitted to encouraging more
accurate and therefore effectivepractice, and so I think it's
really, really important that weget honest about what our
practice is actually doing andwhat it is actually not doing.
(14:58):
So here are some sacred cowsthat I think you're gonna be
maybe considering orreconsidering as a result of
hearing about this particularpiece of research.
Here's the first one Staticstretching can make you weak as
it overstretches your tissues,and overstretch tissues are weak
(15:23):
.
So that's the first thing Ithink we're going to be
reconsidering as a result ofthis evidence.
Okay, that's number one.
That's a big one.
Number two stretching is bestfor flexibility when things are
too tight and therefore toostrong.
Yes, okay, that's another onewe're going to look at.
(15:46):
And then, finally, the type ofstretching we do in Yin can
cause injury throughover-stretching.
That's a big one.
That is a huge one.
And it's not just for teachers.
How many students do you hearfrom that?
You know they felt like theyneeded to come to a class or
(16:10):
have a teacher to help them, toquote do it right so they don't
quote hurt themselves, right.
So this is a very pervasivemyth in our industry and while I
can't like really just 100%nail it right in the center, I
am definitely going to help youto reconsider some of these
(16:33):
myths and how we might get to alittle bit more truth.
So the first study, as Imentioned, that I want to
discuss is all about stretching.
Most studies, the vast majorityof studies about static
stretching are examiningflexibility or range of motion.
(16:54):
Okay, this meta-analysis isdifferent.
There's not many at all whichare studying static stretching
for reasons other thanflexibility or range of motion.
In fact, this meta-analysis ofanimal studies was conducted to
(17:16):
determine whether stretching cangenerate adequate mechanical
tension to induce musclehypertrophy.
What is muscle hypertrophy, youmight be asking me.
So it is a very complicatedthing, but let's just say for
(17:38):
simplicity that it is musclegrowth.
There are many, many factorswhich may contribute to muscle
hypertrophy.
If I'm being honest, I'll haveto tell you that there are still
a lot of unanswered questionsabout what causes muscle growth.
But in general, musclehypertrophy is muscles getting
(18:01):
bigger as a result of mechanicaltension.
So all those bodybuilders whoare headed into the gym every
single day are mainly trying toincrease the size of their
muscles and, as a consequence,also getting stronger.
But their primary goal ishypertrophy, whereas, for
(18:24):
example, a powerlifter, theyjust want to lift something
really heavy one or two times.
They're not interested inmuscle hypertrophy, muscle
growth.
They're interested in strength.
So the two are correlated, butthey are not exactly the same
thing.
So this study wanted to look atif you could use a stretching
(18:46):
protocol to generate enoughmechanical tension to induce
muscle hypertrophy or growth.
The reason this study reallysticks out to me is because it
bridges my two big passions,which are heavy resistance
training and Yin yoga.
(19:07):
It's like a marriage made inheaven.
So here's why the researcherswanted to know if stretching can
do the same thing as resistancetraining, because and I'm going
to quote the study directlyhere muscular hypertrophy
depends on metabolic exhaustionas well as mechanical load on
(19:28):
the muscle.
Chemical tension seems to bethe crucial factor to stimulate
protein synthesis.
Can I break that down for you?
So basically, whether a muscleis stretching due to moving a
heavy weight through a fullrange of motion or it's due to a
(19:49):
stretch of sufficient intensityand duration, the body will
have a similar adaptive response.
That's kind of their hypothesis.
So in this meta-analysis theywere looking for data
specifically on musclecross-sectional area.
(20:13):
So in yoga we're alwaysconcerned about the length of
muscle.
When we're looking at studieslooking at hypertrophy, they're
looking at the width of themuscle, that is, the
cross-sectional area.
They were also looking at fibercross-sectional area, so those
would be the individual feshklesand in some limited studies
(20:34):
they also looked at fiber numberand length.
We will not be considering eachof these separately, as that's
going to be way too in the weedsfor this discussion.
We're just going to think ofall of these as hypertrophy.
So now that I've broken thatdown, here is the official
hypothesis of this meta-analysis, which I took directly from the
(20:58):
introduction Stretch trainingperformed with sufficient
intensity leads to highmechanical load that can trigger
muscular hypertrophy as along-term training effect.
That's what they were testingfor.
This study pulled data from 16studies.
(21:19):
Those were only 16 of the many,many studies that they pulled
actually meet the criteria forhaving collected the data that
we just talked about using aduration stretch protocol.
And the 16 studies all usedanimals as subjects, mostly mice
(21:39):
and chickens.
So you might be wondering howuseful, mandy, is this
information, even to me, ifthey're looking at research on
animals?
We'll kind of touch on that ina second, but I want to let you
know first of all that there arenot many studies that are
looking specifically athypertrophy as a result of
(22:00):
duration stretching on humans.
There are very few.
I think there's less than fiveor six that's not to say right
and there are some which we'reactually going to discuss, I
promise, the other reason thatthey used animals in this
protocol is because many of theinterventions they use, the ways
(22:22):
that they stretched the muscles, would not be appropriate or
ethical to perform on humans, sothat's why we use animals.
I'm not going to weigh in onthe ethics of using animals.
I have to say I'm prettyuncomfortable with it as well,
(22:44):
but also the world needs data,so it's a tricky subject.
Okay, so now that I've told youthe hypothesis and the general
study design, what were theresults of this analysis?
This is the question we allwant answered.
(23:06):
I want the results.
So here they are.
The findings show an almostcontinuous positive effect of
long term stretching onhypertrophy, which means that in
nearly every included study,there was only one on a single
test subject, by the way whichdid not have a positive result,
(23:30):
and positive means it did whatthey expected.
So what that means is that thisduration stretching on these
animals resulted in biggermuscles.
In some cases, the musclesactually got stronger and in
some cases, the stretch trainingeven improved muscle
(23:51):
performance.
Muscle performance generallyrefers to maximum strength, so
that's basically the maximumamount of weight that you can
lift once, and speed strength,which is how quickly can you
lift a heavy weight.
So that improved as well as aresult, my friends, of
(24:15):
stretching.
So already I hope you see whereI'm going.
When it comes to our sacredcows, right, they're just
dropping like flies.
Stretching improved strengthand, in some cases, performance.
However, most of the studiesshowed an increase in the amount
(24:38):
of time it took a muscle tocontract after stretch training.
So, in other words, performancewas decreased in all but a very
limited amount of data.
So I think what we can saythere is that it is thus far
inconclusive as to whetherstatic stretching can improve
muscle performance, but itappears to be able to improve
(25:00):
strength, okay.
So a question you might behaving is that obviously, humans
and animals are different.
You are correct.
For example, the proteinsynthesis rate that was one of
the things that they weretesting for.
Protein synthesis is requiredfor muscle growth.
(25:21):
We have to increase the size ofproteins, the amount of
proteins.
It's a little bit unclear tothis day what exactly is
happening, but protein synthesisis important and we do know
that humans experience a slowerprotein synthesis rate than
chickens or mice.
(25:42):
Chickens and mice are prettyquick within a few days, humans
a couple of weeks.
However, we still have muscleprotein synthesis Okay, and
there are enough similarities toconclude that stretch training
could be beneficial.
These were the conclusions ofthe study.
Stretch training could bebeneficial for reducing muscle
loss or stimulating muscle gainin people who can't do strength
(26:06):
training.
There is, my dear listener,some data about stretch training
for humans which I would liketo read somewhat directly from
the paper.
There's not that much data, soit won't take me long.
(26:29):
Okay, so initial human studiesshow that long-term stretching
interventions for several weekscan induce hypertrophic effects
and or increase maximum strength.
For example, a study, simpson etal were able to achieve an
(26:52):
average increase of 5.6% inmuscle cross-sectional area
through a stretchingintervention with a duration of
3 minutes, 3 days per week for 6weeks.
This, I would say, is probablythe most relevant study to what
we do in Yin, because they werestretching 3 days a week for 3
(27:16):
minutes, which is a Yin holdright For 6 weeks.
Now I don't want you to thinkthat they are just doing a bunch
of different stretches for 3minutes.
They are looking specificallyat a target muscle.
So a lot of times they're goingto be doing the calf muscles,
for example, but maybe you coulddo your hamstrings right, so
(27:38):
any muscle that you can stretchin a very consistent way would
be applicable to the research, Iwould think.
So what that looks like is youor your student is going to be
stretching 3 times a week.
You're going to stretch thosehamstrings for 3 minutes and
(28:00):
you're going to do that for 6weeks and not only was there an
increase in strength, but it wasalso an increase in the
cross-sectional area, basicallythe mass of the muscle.
Okay, so the others have lessapplicability to our practice,
but I think that they arehelpful just for our body of
(28:23):
knowledge.
So in Panini at all, they foundan increase in muscle
cross-sectional area of 23%,plus or minus 14% after a
12-week stretching intervention,with stretching durations up to
15 minutes per training session.
So what you may have noticedthere is that the results were
(28:44):
significantly higher, but alsothe duration of the stretch was
15 minutes per training session.
And if you're like me, by theway, I have not yet, but if
you're like me, you're like holysheesh.
I got to look at that research,I got to look up Panini at all
and I have to see what were theother parameters, what were the
(29:06):
other methods of this 12-weekstretching intervention, and I
want to let you know that I amgoing to provide links to each
of the studies that I mentionedin this podcast so that you can
do just that.
There is a citation for everysingle piece of research in this
(29:29):
study.
That was included.
Okay, in Nelson et al, theydemonstrated a 29% increase in
maximal strength afterstretching the calf muscles for
30 seconds four times three daysa week for 10 weeks.
(29:51):
So this again pretty applicable.
And the increase was phenomenal29%.
I mean guys, any gym bro wouldlove a 29% increase in a
strength in any muscle group injust 10 weeks.
(30:12):
Right, and it doesn't requirelifting heavy weight or doing
calf raises, which are alsoreally fun, but it's just
stretching.
And then here's another onewhich is very, very interesting
and compelling.
In Coconin et al, they achievesignificant improvements in
various performance tests, suchas a one rep max, knee extension
(30:36):
and knee flexion.
Let me break that down for you.
Knee extension will be workingyour quadriceps, so how much
could your quadriceps lift toextend your knee one time?
Knee flexion will be workingwith your hamstrings, so how
much could you, how much loadcould you withstand, to
(30:56):
basically bend your knee?
That's the knee flexion test.
So those both improved.
The standing long jump and highjump improved.
So those are looking more atperformance and elasticity.
And the protocol was staticstretching for 40 minutes per
session, three days a week for10 weeks.
(31:19):
So stretching a specific musclein this case it would be the
calves for actually that's nottrue.
It is not mentioned.
We're going to have to look upthat citation, guys and check it
out.
That coconut at all, 40 minutesper session, three days a week
for 10 weeks this is excessive.
This is not going to show up ina neighborhood yin class, but
(31:43):
it's really interesting to knowthat you can improve your
strength significantly, your onerep max significantly, just
through stretching and somepretty serious stretching.
So what this does right away isI hope it shows us that
(32:04):
stretching does not make youweak, even like really extreme
stretching.
So we'll just take that in fora second, and you might be
thinking some of these timingsare really excessive and I want
you to know that yes, they are.
(32:25):
The other thing that was prettyextreme was the intensity, so
that refers to how hard themuscle is being stretched.
Like I said, I have not lookedup these citations.
I just needed to keep myselffrom going too far down the
rabbit hole for the purposes ofthis podcast and actually
getting it out to you onWednesday at 9 am.
(32:49):
But if you look at the datafrom the animals, they were
stretching the muscle that theyhad chosen from the animal,
anywhere from 12% to up to 30%of body weight, which is very,
very, very extreme.
But again, I think what thisshows us is that over stretching
(33:10):
is highly unlikely to causeexcessive weakness.
So we can eliminate this myth,perhaps that stretching makes
you weak.
That's the first one.
Here's another myth that mightstill be true, but it's not a
(33:32):
slam dunk.
Stretching negatively impactsperformance.
We don't have firm conclusionson this yet, but another study
that was simply cited in thismeta-analysis used a daily
duration stretching protocol forthe plantar flexors.
(33:53):
So those are the muscles whichhelp you point your foot, and
this research showed significantincreases in maximal strength,
muscle thickness and flexibility.
So here we see at least withthe plantar flexors, flexibility
(34:16):
and strength can be improvedsimultaneously.
I think that the currentnarrative, not just in the yoga
world but also in the strengthworld, is that you can only have
one at the expense of the other.
But what this showed wasstretching could improve
strength and flexibility, and Ithink this goes in hand and hand
(34:39):
with other research that I haveread which shows that
resistance training outperformsstatic stretching in improving
range of motion.
So, in other words, liftingweights can help you to improve
(35:01):
your range of motion about aswell as static stretching.
However, research also showsthat resistance training plus
static stretching is the verybest for improving range of
motion.
So I hope that your head iskind of exploding right now With
(35:25):
all of this great information,which can hopefully help you as
a practitioner, and definitelyyou if you're a teacher, to feel
more comfortable and safe aboutrecommending yin yoga or
teaching yin yoga, knowing thatit is very unlikely that your
students will be overstretched.
(35:46):
So another thing I want to pointout about this data is that
some of the studies stretch theanimals muscles continuously for
days or weeks and those studiesdemonstrated the highest effect
size, the best results.
So, for obvious reasons, that'snot going to be something that
(36:06):
we're going to do in yin andthis probably never even going
to be studied on humans.
It's probably not applicableeven in a clinical setting,
although I would imagine ifsomeone is immobilized somehow
anyway, it could be helpful.
But what I wanted to show youagain is that it is not
dangerous to stretch my hope inreviewing this study for you is
(36:26):
that we can start to change theconversation about weak
flexibility and strong tightness, and I think that this is also
very compelling informationabout our industry fears about
overstretching.
Do some people experience painas a result of their practice?
Yes, I'm not here to gaslightanyone who has experienced pain
(36:47):
as a result of stretching theiryin practice, their vinyasa
practice.
Pain happens.
The question is is it due toover stretching?
The evidence here and elsewheresays no.
I will touch more on this injust a little bit.
So let's talk about anotherstudy which talks about
(37:08):
stretching and other thingsoutside of the realm of
flexibility.
This was a study on rats.
The scientists injected theback of the rat with an
inflammatory substance calledcaragenin, and if you are
remembering this word, caragenin, it's probably because you read
(37:31):
it on the back of your oat milkcontainer, your almond milk,
your coconut milk container.
It was used widely in all ofthose non-dairy milks as a
binder.
I think that it has sort ofbeen outlawed, but I'm still
seeing it, so maybe it's stillallowed in certain percentages
in these products.
(37:52):
Ever since I read this studyseveral years ago, though, I
have been avoiding carageninlike the plague, because it was
literally used to cause pain andinflammation in these rats, and
, yes, were they getting a lotmore caragenin than you do in
your oat milk?
Absolutely Still, I don't thinkI want any part of it.
(38:13):
So, after they injected theserats with this caragenin
substance and they witnessedthat there was pain and
inflammation, they thenproceeded to stretch the back of
the rat and there's a diagramshowing you how.
It stretched the rat for 10minutes twice daily, and what
they found was that protocolreduced inflammation and
(38:34):
improved pain within two weeksof the caragenin injection.
A follow-up study to that studyshowed that the reduction of
inflammation was due to thereduction of pro-inflammatory
immune cells.
In the actual research, itbreaks down the different immune
cells and all of the differentinformation.
I don't think we need to gothat into the weeds for this.
(38:55):
Basically, what it's saying,though, is that there was a
reduction of inflammation, whichthey then concluded was a
reduction in pro-inflammatoryimmune cells.
So, as you know, I mostly workwith people who are managing a
pain issue, so inflammation is amajor concern, and probably
(39:17):
should be a major concern, bythe way, for every adult on the
planet, since inflammation is adirect cause of pretty much
every chronic illness that wehave.
So even though the data showsthat static stretching resolves
inflammation in rats injectedwith caragenin, that may feel
like wow, mandy, that is reallya wide bridge to cover here.
(39:40):
To me, reading research likethis is kind of a what is the
harm in recommending staticstretches to my clients, like,
yes, we don't have this data onhumans yet, but static
stretching feels really good, itis almost universally
(40:01):
well-tolerated, there is nocopay, there are no side effects
, or very few side effects,right.
So if it's possible that thisdata could transfer to humans,
why shouldn't I just kind of tryit out?
And so sometimes we useresearch, not because it's super
conclusive, but because there'sreally no harm in trying with
(40:23):
something like this and so manyof the things we do in this
profession or in this practice.
I want to talk about just onemore study.
This one will be brief.
This study showed thatstretching can help tendon
injuries to heal.
Tendon injuries to heal.
Now I remember learning in myteacher training years ago my
(40:46):
200 hour that tendons have noindependent blood supply and
therefore they never really healonce they're stretched.
They're stretched for life,right Like the credit card
analogy in the the Yin site.
So the complete guide to Yinyoga by Bernie Clark.
In fact I probably taught thismyself in my 200 hour trainings
(41:07):
that I have taught.
But this is a really revelatorypiece of evidence because it
showed, it concluded, thatdynamic uniaxial stretching
stimulates the biomechanicalconditions of natural tendons by
inducing tenogenicdifferentiation, alignment of
(41:28):
cells and extracellular matrix,and promotes tendon repair and
regeneration, promotes tendonrepair.
So we're all concerned aboutoverstretching, but it turns out
static stretching couldactually promote tendon repair
and regeneration and all ofthose other wonderful things too
(41:51):
, inducing tenogenicdifferentiation and lining cells
, ecm.
So I will give you the link tothis study, I promise, so you
can look at it yourself.
But I will say that what theyconcluded this was a meta
analysis, by the way.
So they looked at a bunch ofdifferent studies that were
looking at natural tendons andalso lab generated tendons.
(42:14):
The frequency of an effectiveprotocol and bioreactors is not
usually higher than 1 Hertz,which is a unit of frequency
equivalent to one event or cycleper second.
Okay, one Hertz and between 1and 12% strain.
So they strained the tendonbetween 1 and 12%.
(42:36):
That was the.
You know, depending on thestudy, some did 1%, some did 12,
some did 8, some 10, 6, somedid 3.
But all of them were somewhateffective in wound healing.
So you might be like, okay, howdoes that break down in my body?
What is?
1%, 12% feel like strain for atendon and it is extremely
(43:02):
difficult to conceptualize, tomeasure, and the fact is you're
never really going to know.
Have you strained yourhamstring, the proximal
hamstrings tendon?
6%, for example, in yourcaterpillar pose?
Like that's impossible, becausestretching a tendon is really
challenging when you're quotestretching, since the myofascia,
(43:24):
that's the muscle with itsfascia, takes up most of the
stress.
It's pretty stretchy and thenwhen you're stopped stretching
it, it's elastic and it comesback to shape.
So the myofascia is going totake up the primary, the largest
amount of the tension, and thenthere will be other structures
that can kind of take up some ofthe tension.
(43:45):
And only when the tensionreaches a sufficient level of
intensity will you actually bestretching your tendon, which is
why the best way to stretch atendon is actually resistance
training.
So I want to mention somethingabout this.
So, working with people wholive with chronic pain, who are
(44:07):
already a little plugged intothe yoga world, I encounter many
, many clients who have painwhich they attribute to over
stretching, specifically atendon attachment sites.
The ones that pop up the mostin yoga are the proximal
(44:32):
hamstrings tendons, so that'swhere your hamstrings attach to
your pelvis, at the sittingbones, the ischial tuberosities,
and a lot of your yogis.
Out there are like oh, I havethat pain.
Right, it's like an achy.
Sometimes it can be very sharp,almost a sick feeling.
It's like you just think I gotto stretch it, I have to stretch
(44:52):
it.
And then another one is thelateral hip.
That would be where the glutealtendon attaches, just below the
greater trochanter.
Those are the most common foryogis and even though and, by
the way, the feeling on that oneis the same just achy,
sometimes sharp, certainmovements really really bad,
(45:15):
wakes you up at night, verypainful when sitting, like those
are all the kind of things thathappen and these are known.
Potentially.
Obviously I can't diagnose youeither in person or over the
podcast, but these are symptomswhich are typically attributed
(45:37):
to a tendonopathy and eventhough stretching can reduce
inflammation and it canpotentially help with tendon
regeneration and repair,stretching is the very last
thing you should do for theseinjuries.
So I didn't feel like it wouldbe responsible for me to give
(45:57):
you all this great informationabout stretching, and if you
potentially have an issue in oneof these areas and you would
like help with it, you cancertainly reach out to me.
I do online coaching.
I've helped many, many peoplewith this problem or you can
find someone else who isqualified to help you with a
tendonopathy.
I have found that tendonopathyprotocol is really, really
(46:18):
helpful, even for people whohave never had a diagnosis of
tendonopathy.
So in this episode, you learnedthat stretching is so much more
complicated than you have beenled to believe and potentially
so much more beneficial than forjust range of motion and
flexibility.
(46:39):
I hope you've learned that itis not as simple as stretch it.
To lengthen it right Stretchingcould increase the cross
sectional area of your muscle,and I hope that you've also
learned that many of ourconcerns about overstretching
and injury are unfounded when wego down the evidence rabbit
(47:01):
hole.
You have also learned that diduration and dynamic stretching
can potentially potentially helpto resolve inflammation and to
speed up tissue healing.
So the question is how will youuse this information in your
teaching or practice?
At this moment, it might behelpful to just reflect a little
(47:24):
bit on that.
So here's a question for youWill you lean into the benefits
of stretching other thanflexibility?
Will you change your languagearound the postures, around
stretching, around the benefitsof stretching?
(47:47):
If I'm honest, I would say thatI would actually really love to
hear your responses to thesequestions.
I would love to hear if youhave any follow up questions for
me or if you have read researchthat you think would be an
interesting adjunct to whatwe've discussed here on the
(48:08):
podcast today.
So to do that, I wouldrecommend that you join my
private Facebook group.
It's called Movement forHealing.
It is a great place just to askme questions and pick my brain.
I'm going to leave a link in theshow notes, and here's the
(48:29):
other reason why you shoulddefinitely consider joining my
Facebook group.
I am going to put all of thelinks to the research which I
have discussed in the Movementfor Healing Facebook group.
I only get so many charactersin my show notes, so there's no
(48:54):
way I could include this in theshow notes.
So type in to Facebook,movement for Healing, or click
the link in the show notes, andthat will take you right there.
You will have to request to beallowed into the group and then,
once I approve you, you'll seeall of the articles right there.
(49:16):
All you have to do is click.
All of these are open accessarticles, so obviously I've only
scratched the surface here onhow evidence can enhance your
teaching and your personalpractice.
Next week, I am very, veryexcited to tell you about
research that is related toother important aspects of our
(49:39):
practice and many of us wouldsay the more important aspects
of our practice.
That would be nervous systemregulation, mindfulness,
attention, and I am going toapply these specifically to my
great passion, which is paincare.
Thank you so much for listeningand for your interest in
(50:01):
research literacy.
Welcome to the Yin Yoga Podcast.
I'm your host, mandy Ryle, andI am so excited for the third in
our series Becoming anEvidence-Informed Yin Yoga
Teacher or Student.
As promised, today, I will bereviewing some interesting
evidence for you so that you canstart to see, number one, how
(00:24):
you put what you have beenlearning actually into the
process of reading andprocessing research.
Number two, so you can see howresearch literacy directly
impacts you as a teacher or apractitioner of Yin.
And then, finally, so that youcan increase your body of
(00:46):
knowledge around something soessential to our practice that
would be stretching.
There is a pervasive myth inour practice that stretching is
just for gaining range of motion, and I am going to present some
(01:07):
evidence for you in thisepisode which will help you to
see all of the wonderful thingsthat happen as a result of
stretching, and I really hopethat you can bring this into
your teaching or into yourpractice immediately.
I'm going to let you know alsothat I am providing the full
text links for every singlepiece of research that I will be
(01:31):
discussing in this episode.
However, my show notes do notallow enough room for me to put
all of those full text linksinto the podcast players, so
here's what I'll do.
Instead, I'm going to inviteyou to please join my Facebook
group.
It's a private group calledMovement for Healing.
(01:53):
Once approved in that group,you will see each of the full
text links for the articles, andyou will also have an
opportunity to ask any follow upquestions that you might have
or to add any comments that youwould like to add.
I will leave a link to theMovement for Healing Facebook
(02:17):
group in the show notes, or youcan just head right to Facebook
and type it in.
Thank you so much for yourinterest in research literacy.
Here is episode number three.
So, as you know, this is thethird episode in my series
(02:45):
Becoming an Evidence-InformedYoung Teacher or Student.
Right here at the outset, Iwant to let you know that there
will be one more episode in thisseries, where I'll be reviewing
evidence related to the nervoussystem and cognitive benefits
of the practice of Yen, and I'llespecially like to highlight
(03:08):
how Yen can contribute to a paincare process, because that is,
after all, my personal specialty.
Today, though, we're going tobe looking at how stretching
specifically influences tissues,and I chose the three studies
that I'll be discussing in thisepisode because they illuminate
(03:31):
some outcomes of practice, someconsequences of stretching that
I do not think are widely knownor certainly understood by our
industry, yen Yoga and Yoga ingeneral.
So I am very excited to tellyou this information, because I
(03:52):
think it's really going tobroaden your horizon and your
love and awe for what we areactually doing in our practice.
So before we dive in, though, Iwant to make sure that you
understand that reading one ortwo or three studies, or even
(04:12):
six studies, is not reallyenough to truly be an expert on
a topic.
I mean, think about it.
There is a reason that researchmust be duplicated by multiple
organizations and differentscientists before it's actually
considered conclusive, right?
So when a new interestingconclusion comes up in a piece
(04:34):
of research, the next step isfor somebody else to try to
duplicate those results.
And for the same reason, it'simportant that we don't limit
our knowledge to just one study,but that we instead have a
broad range of research that wecan draw from.
So a lot of times, we sort ofuse evidence as like a blunt
(04:57):
instrument to confirm our bias.
We essentially would likecherry pick some evidence so
that we can back up what we'retrying to say, the point we're
trying to make.
But there is a better way touse evidence.
I think that a better strategyis to use evidence to contribute
(05:21):
to your personal body ofknowledge so that you can
continue to develop your ownskills.
A big part of this iscontinually challenging your own
biases and assumptions.
If you find a study thathappened 20 years ago and you're
like this is great.
This is everything that I'vebeen saying.
(05:42):
I highly recommend that youmake sure that you look at more
recent evidence as well, becauseoften you will find that there
is some contradiction, somedevelopment, as maybe methods or
technologies have advanced.
Becoming a really trulywonderful evidence informed
(06:06):
teacher will require quite a bitof humility, and in fact, I
think that's probably true forany profession, not just yoga
teachers and yen teachersspecifically.
So that is a little bittroublesome because if you're
just starting out in yourresearch literacy journey,
(06:30):
you're going to have to startwith one or two or three or six
studies.
Right, and that's okay.
It just means that you'rebuilding up your body of
knowledge over time and you willaccumulate knowledge that can
help you to serve yourpopulation of students better or
to customize your personalpractice to become even more
(06:50):
effective.
That can happen in one or twoor three studies.
So I say this also to let youknow that the studies that I'm
going to discuss here are just afraction of the research that
has helped me to form my ownopinions and to develop specific
teaching protocols orstrategies.
Okay, I am not setting the holygrail by these particular
(07:13):
studies, okay.
So before we get startedlooking specifically at the
research, I wanted to kind ofback up and bring this to more
of a practical realm, becausewhat I've noticed about training
yoga teachers all these yearsis that we really do best when
we know how this is going to beapplied specifically to our
(07:37):
practice or to our teaching.
So let me help you toconceptualize how you will apply
your new research literacy thatyou've been building over these
last few weeks.
For the most part, yourstudents won't really see a huge
(07:58):
difference in your teaching,right?
They won't understand that whatthey see is just the very tip
of the iceberg and that yourbody of knowledge and your skill
and your wisdom is like therest of the iceberg that's under
the ocean, right?
Massive amounts of informationthat you have to bring to bear
(08:20):
at any given moment in theteaching experience or in a
learning experience, buthopefully your students will
feel the difference in theresults that they're getting.
I know that we like to talkabout non ambition and practice
and indeed that is importantwhen you're in a practice
experience but we need to berealistic here.
(08:42):
People come to yoga becausethey're looking for a result.
That's the only reason anyonedoes anything right.
So, regardless of what thatresult is, my assumption is that
you can probably find evidenceto help you, to help your
students to get to that resultmore efficiently, more quickly,
(09:03):
more completely.
To be evidence informed willinfluence your, your post
choices, your sequencing.
It's going to impact yourtheming and that's gonna be much
more important in next week'sepisode.
It's going to impact your handson assisting and perhaps most
(09:25):
importantly I believe, it'sgoing to impact the language
that you use, the words that youchoose.
So let's just start with thatone the language.
How is your languagepotentially going to change as a
result of being evidenceinformed?
I'm gonna go out on a limb hereand say that the first thing is
(09:46):
you might avoid results-basedlanguage that would indicate
that a quote stretch end quotecould permanently lengthen
tissues.
So we might not make claimslike that anymore that Yin yoga
makes you more flexible becausethe tissues are lengthening.
(10:06):
You'll understand more aboutthat as we go today.
You might instead focus onother benefits of the poses and
you will have the information toback that up.
Another thing that might happento your language is you might
reduce your language around thedanger or safety of poses.
(10:29):
I would say that's probably thebiggest difference that it's
made in my teaching and if thathas piqued your interest, that
you might change your thinkingor language around danger or
safety of poses.
Make sure that you tune into theepisode next week because
that's gonna be the lion's shareof what we're gonna talk about,
(10:51):
because I think it's so, soimportant.
So if you are not currentlysubscribed to the podcast,
quickly, just scroll up, hitthat subscribe.
Some podcast apps also allowyou to opt in to alerts.
Make sure that you have optedinto those because I don't want
you to miss that.
That one is incrediblyimportant for you, for your
(11:12):
students, for our profession.
So how could being evidenceinformed potentially change your
pose choices?
Once evidence informed, I thinkthat you will understand that
more intensity to a stretch willnot change the length of
muscles, so you might start toavoid some of the more gnarly
(11:34):
difficult, harrowing poses,understanding that results can
happen with a much smaller levelof intensity.
Here's another thing that mightchange your pose choices is if
you understand that pain is notthe result of tightness.
(11:55):
Pain is not the result oftightness.
I just literally obliterated asacred cow just now.
I know we're gonna be doing alot of that in this episode.
So once you understand thatpain is not the result of
tightness, you might start toavoid prescribing or teaching
specific stretches for thatpurpose, and I know as a yoga
(12:22):
teacher myself, as a trainer ofteachers, people are asking us
all the time for a pose tostretch X, y or Z because it
hurts.
So perhaps being evidenceinformed could help you to give
more helpful, beneficialsuggestions to your students and
(12:44):
could potentially help you tobe empowered to address the true
driver of tightness andsensitivity, which is the
nervous system.
We're gonna talk more aboutthat next week.
Being evidence informed, youwill likely develop strategies
for helping to your students toembrace their range of motion,
(13:09):
and you will do this because youwill understand that range of
motion is largely a product ofgenetics and bone morphology and
that no amount of stretchingcan change those.
So perhaps being evidenceinformed will help you to
support students in working,accepting, being content with
(13:30):
the body that they have.
So, as I said, I'm gonna besticking today with research
that specifically addresses howduration stretching impacts
tissues.
And let me give a littledisclaimer here Research rarely
gives us an ironclad conclusion.
(13:51):
Most of the time, it raisesmore questions, right, it's sort
of like, okay, we got thisresult, but now we don't really
know why.
Now we need to look at that.
We have more questions than wehad when we started.
But what research does do is itmoves us slowly, inexorably,
over time toward more effectivestrategies.
(14:14):
It gives us more what, how,when, and that can be incredibly
useful to a yoga professionaland, I believe, to someone who
simply loves the practice of theend.
So the reason I chose this firststudy is because it lays a few
sacred cows in the yin world.
(14:35):
Now I don't wanna come in andjust steal your lollipop, but as
a teacher, my mission is I amcommitted to encouraging more
accurate and therefore effectivepractice, and so I think it's
really, really important that weget honest about what our
practice is actually doing andwhat it is actually not doing.
(14:58):
So here are some sacred cowsthat I think you're gonna be
maybe considering orreconsidering as a result of
hearing about this particularpiece of research.
Here's the first one Staticstretching can make you weak as
it overstretches your tissues,and overstretch tissues are weak
(15:23):
.
So that's the first thing Ithink we're going to be
reconsidering as a result ofthis evidence.
Okay, that's number one.
That's a big one.
Number two stretching is bestfor flexibility when things are
too tight and therefore toostrong.
Yes, okay, that's another onewe're going to look at.
(15:46):
And then, finally, the type ofstretching we do in Yin can
cause injury throughover-stretching.
That's a big one.
That is a huge one.
And it's not just for teachers.
How many students do you hearfrom that?
You know they felt like theyneeded to come to a class or
(16:10):
have a teacher to help them, toquote do it right so they don't
quote hurt themselves, right.
So this is a very pervasivemyth in our industry and while I
can't like really just 100%nail it right in the center, I
am definitely going to help youto reconsider some of these
(16:33):
myths and how we might get to alittle bit more truth.
So the first study, as Imentioned, that I want to
discuss is all about stretching.
Most studies, the vast majorityof studies about static
stretching are examiningflexibility or range of motion.
(16:54):
Okay, this meta-analysis isdifferent.
There's not many at all whichare studying static stretching
for reasons other thanflexibility or range of motion.
In fact, this meta-analysis ofanimal studies was conducted to
(17:16):
determine whether stretching cangenerate adequate mechanical
tension to induce musclehypertrophy.
What is muscle hypertrophy, youmight be asking me.
So it is a very complicatedthing, but let's just say for
(17:38):
simplicity that it is musclegrowth.
There are many, many factorswhich may contribute to muscle
hypertrophy.
If I'm being honest, I'll haveto tell you that there are still
a lot of unanswered questionsabout what causes muscle growth.
But in general, musclehypertrophy is muscles getting
(18:01):
bigger as a result of mechanicaltension.
So all those bodybuilders whoare headed into the gym every
single day are mainly trying toincrease the size of their
muscles and, as a consequence,also getting stronger.
But their primary goal ishypertrophy, whereas, for
(18:24):
example, a powerlifter, theyjust want to lift something
really heavy one or two times.
They're not interested inmuscle hypertrophy, muscle
growth.
They're interested in strength.
So the two are correlated, butthey are not exactly the same
thing.
So this study wanted to look atif you could use a stretching
(18:46):
protocol to generate enoughmechanical tension to induce
muscle hypertrophy or growth.
The reason this study reallysticks out to me is because it
bridges my two big passions,which are heavy resistance
training and Yin yoga.
(19:07):
It's like a marriage made inheaven.
So here's why the researcherswanted to know if stretching can
do the same thing as resistancetraining, because and I'm going
to quote the study directlyhere muscular hypertrophy
depends on metabolic exhaustionas well as mechanical load on
(19:28):
the muscle.
Chemical tension seems to bethe crucial factor to stimulate
protein synthesis.
Can I break that down for you?
So basically, whether a muscleis stretching due to moving a
heavy weight through a fullrange of motion or it's due to a
(19:49):
stretch of sufficient intensityand duration, the body will
have a similar adaptive response.
That's kind of their hypothesis.
So in this meta-analysis theywere looking for data
specifically on musclecross-sectional area.
(20:13):
So in yoga we're alwaysconcerned about the length of
muscle.
When we're looking at studieslooking at hypertrophy, they're
looking at the width of themuscle, that is, the
cross-sectional area.
They were also looking at fibercross-sectional area, so those
would be the individual feshklesand in some limited studies
(20:34):
they also looked at fiber numberand length.
We will not be considering eachof these separately, as that's
going to be way too in the weedsfor this discussion.
We're just going to think ofall of these as hypertrophy.
So now that I've broken thatdown, here is the official
hypothesis of this meta-analysis, which I took directly from the
(20:58):
introduction Stretch trainingperformed with sufficient
intensity leads to highmechanical load that can trigger
muscular hypertrophy as along-term training effect.
That's what they were testingfor.
This study pulled data from 16studies.
(21:19):
Those were only 16 of the many,many studies that they pulled
actually meet the criteria forhaving collected the data that
we just talked about using aduration stretch protocol.
And the 16 studies all usedanimals as subjects, mostly mice
(21:39):
and chickens.
So you might be wondering howuseful, mandy, is this
information, even to me, ifthey're looking at research on
animals?
We'll kind of touch on that ina second, but I want to let you
know first of all that there arenot many studies that are
looking specifically athypertrophy as a result of
(22:00):
duration stretching on humans.
There are very few.
I think there's less than fiveor six that's not to say right
and there are some which we'reactually going to discuss, I
promise, the other reason thatthey used animals in this
protocol is because many of theinterventions they use, the ways
(22:22):
that they stretched the muscles, would not be appropriate or
ethical to perform on humans, sothat's why we use animals.
I'm not going to weigh in onthe ethics of using animals.
I have to say I'm prettyuncomfortable with it as well,
(22:44):
but also the world needs data,so it's a tricky subject.
Okay, so now that I've told youthe hypothesis and the general
study design, what were theresults of this analysis?
This is the question we allwant answered.
(23:06):
I want the results.
So here they are.
The findings show an almostcontinuous positive effect of
long term stretching onhypertrophy, which means that in
nearly every included study,there was only one on a single
test subject, by the way whichdid not have a positive result,
(23:30):
and positive means it did whatthey expected.
So what that means is that thisduration stretching on these
animals resulted in biggermuscles.
In some cases, the musclesactually got stronger and in
some cases, the stretch trainingeven improved muscle
(23:51):
performance.
Muscle performance generallyrefers to maximum strength, so
that's basically the maximumamount of weight that you can
lift once, and speed strength,which is how quickly can you
lift a heavy weight.
So that improved as well as aresult, my friends, of
(24:15):
stretching.
So already I hope you see whereI'm going.
When it comes to our sacredcows, right, they're just
dropping like flies.
Stretching improved strengthand, in some cases, performance.
However, most of the studiesshowed an increase in the amount
(24:38):
of time it took a muscle tocontract after stretch training.
So, in other words, performancewas decreased in all but a very
limited amount of data.
So I think what we can saythere is that it is thus far
inconclusive as to whetherstatic stretching can improve
muscle performance, but itappears to be able to improve
(25:00):
strength, okay.
So a question you might behaving is that obviously, humans
and animals are different.
You are correct.
For example, the proteinsynthesis rate that was one of
the things that they weretesting for.
Protein synthesis is requiredfor muscle growth.
(25:21):
We have to increase the size ofproteins, the amount of
proteins.
It's a little bit unclear tothis day what exactly is
happening, but protein synthesisis important and we do know
that humans experience a slowerprotein synthesis rate than
chickens or mice.
(25:42):
Chickens and mice are prettyquick within a few days, humans
a couple of weeks.
However, we still have muscleprotein synthesis Okay, and
there are enough similarities toconclude that stretch training
could be beneficial.
These were the conclusions ofthe study.
Stretch training could bebeneficial for reducing muscle
loss or stimulating muscle gainin people who can't do strength
(26:06):
training.
There is, my dear listener,some data about stretch training
for humans which I would liketo read somewhat directly from
the paper.
There's not that much data, soit won't take me long.
(26:29):
Okay, so initial human studiesshow that long-term stretching
interventions for several weekscan induce hypertrophic effects
and or increase maximum strength.
For example, a study, simpson etal were able to achieve an
(26:52):
average increase of 5.6% inmuscle cross-sectional area
through a stretchingintervention with a duration of
3 minutes, 3 days per week for 6weeks.
This, I would say, is probablythe most relevant study to what
we do in Yin, because they werestretching 3 days a week for 3
(27:16):
minutes, which is a Yin holdright For 6 weeks.
Now I don't want you to thinkthat they are just doing a bunch
of different stretches for 3minutes.
They are looking specificallyat a target muscle.
So a lot of times they're goingto be doing the calf muscles,
for example, but maybe you coulddo your hamstrings right, so
(27:38):
any muscle that you can stretchin a very consistent way would
be applicable to the research, Iwould think.
So what that looks like is youor your student is going to be
stretching 3 times a week.
You're going to stretch thosehamstrings for 3 minutes and
(28:00):
you're going to do that for 6weeks and not only was there an
increase in strength, but it wasalso an increase in the
cross-sectional area, basicallythe mass of the muscle.
Okay, so the others have lessapplicability to our practice,
but I think that they arehelpful just for our body of
(28:23):
knowledge.
So in Panini at all, they foundan increase in muscle
cross-sectional area of 23%,plus or minus 14% after a
12-week stretching intervention,with stretching durations up to
15 minutes per training session.
So what you may have noticedthere is that the results were
(28:44):
significantly higher, but alsothe duration of the stretch was
15 minutes per training session.
And if you're like me, by theway, I have not yet, but if
you're like me, you're like holysheesh.
I got to look at that research,I got to look up Panini at all
and I have to see what were theother parameters, what were the
(29:06):
other methods of this 12-weekstretching intervention, and I
want to let you know that I amgoing to provide links to each
of the studies that I mentionedin this podcast so that you can
do just that.
There is a citation for everysingle piece of research in this
(29:29):
study.
That was included.
Okay, in Nelson et al, theydemonstrated a 29% increase in
maximal strength afterstretching the calf muscles for
30 seconds four times three daysa week for 10 weeks.
(29:51):
So this again pretty applicable.
And the increase was phenomenal29%.
I mean guys, any gym bro wouldlove a 29% increase in a
strength in any muscle group injust 10 weeks.
(30:12):
Right, and it doesn't requirelifting heavy weight or doing
calf raises, which are alsoreally fun, but it's just
stretching.
And then here's another onewhich is very, very interesting
and compelling.
In Coconin et al, they achievesignificant improvements in
various performance tests, suchas a one rep max, knee extension
(30:36):
and knee flexion.
Let me break that down for you.
Knee extension will be workingyour quadriceps, so how much
could your quadriceps lift toextend your knee one time?
Knee flexion will be workingwith your hamstrings, so how
much could you, how much loadcould you withstand, to
(30:56):
basically bend your knee?
That's the knee flexion test.
So those both improved.
The standing long jump and highjump improved.
So those are looking more atperformance and elasticity.
And the protocol was staticstretching for 40 minutes per
session, three days a week for10 weeks.
(31:19):
So stretching a specific musclein this case it would be the
calves for actually that's nottrue.
It is not mentioned.
We're going to have to look upthat citation, guys and check it
out.
That coconut at all, 40 minutesper session, three days a week
for 10 weeks this is excessive.
This is not going to show up ina neighborhood yin class, but
(31:43):
it's really interesting to knowthat you can improve your
strength significantly, your onerep max significantly, just
through stretching and somepretty serious stretching.
So what this does right away isI hope it shows us that
(32:04):
stretching does not make youweak, even like really extreme
stretching.
So we'll just take that in fora second, and you might be
thinking some of these timingsare really excessive and I want
you to know that yes, they are.
(32:25):
The other thing that was prettyextreme was the intensity, so
that refers to how hard themuscle is being stretched.
Like I said, I have not lookedup these citations.
I just needed to keep myselffrom going too far down the
rabbit hole for the purposes ofthis podcast and actually
getting it out to you onWednesday at 9 am.
(32:49):
But if you look at the datafrom the animals, they were
stretching the muscle that theyhad chosen from the animal,
anywhere from 12% to up to 30%of body weight, which is very,
very, very extreme.
But again, I think what thisshows us is that over stretching
(33:10):
is highly unlikely to causeexcessive weakness.
So we can eliminate this myth,perhaps that stretching makes
you weak.
That's the first one.
Here's another myth that mightstill be true, but it's not a
(33:32):
slam dunk.
Stretching negatively impactsperformance.
We don't have firm conclusionson this yet, but another study
that was simply cited in thismeta-analysis used a daily
duration stretching protocol forthe plantar flexors.
(33:53):
So those are the muscles whichhelp you point your foot, and
this research showed significantincreases in maximal strength,
muscle thickness and flexibility.
So here we see at least withthe plantar flexors, flexibility
(34:16):
and strength can be improvedsimultaneously.
I think that the currentnarrative, not just in the yoga
world but also in the strengthworld, is that you can only have
one at the expense of the other.
But what this showed wasstretching could improve
strength and flexibility, and Ithink this goes in hand and hand
(34:39):
with other research that I haveread which shows that
resistance training outperformsstatic stretching in improving
range of motion.
So, in other words, liftingweights can help you to improve
(35:01):
your range of motion about aswell as static stretching.
However, research also showsthat resistance training plus
static stretching is the verybest for improving range of
motion.
So I hope that your head iskind of exploding right now With
(35:25):
all of this great information,which can hopefully help you as
a practitioner, and definitelyyou if you're a teacher, to feel
more comfortable and safe aboutrecommending yin yoga or
teaching yin yoga, knowing thatit is very unlikely that your
students will be overstretched.
(35:46):
So another thing I want to pointout about this data is that
some of the studies stretch theanimals muscles continuously for
days or weeks and those studiesdemonstrated the highest effect
size, the best results.
So, for obvious reasons, that'snot going to be something that
(36:06):
we're going to do in yin andthis probably never even going
to be studied on humans.
It's probably not applicableeven in a clinical setting,
although I would imagine ifsomeone is immobilized somehow
anyway, it could be helpful.
But what I wanted to show youagain is that it is not
dangerous to stretch my hope inreviewing this study for you is
(36:26):
that we can start to change theconversation about weak
flexibility and strong tightness, and I think that this is also
very compelling informationabout our industry fears about
overstretching.
Do some people experience painas a result of their practice?
Yes, I'm not here to gaslightanyone who has experienced pain
(36:47):
as a result of stretching theiryin practice, their vinyasa
practice.
Pain happens.
The question is is it due toover stretching?
The evidence here and elsewheresays no.
I will touch more on this injust a little bit.
So let's talk about anotherstudy which talks about
(37:08):
stretching and other thingsoutside of the realm of
flexibility.
This was a study on rats.
The scientists injected theback of the rat with an
inflammatory substance calledcaragenin, and if you are
remembering this word, caragenin, it's probably because you read
(37:31):
it on the back of your oat milkcontainer, your almond milk,
your coconut milk container.
It was used widely in all ofthose non-dairy milks as a
binder.
I think that it has sort ofbeen outlawed, but I'm still
seeing it, so maybe it's stillallowed in certain percentages
in these products.
(37:52):
Ever since I read this studyseveral years ago, though, I
have been avoiding carageninlike the plague, because it was
literally used to cause pain andinflammation in these rats, and
, yes, were they getting a lotmore caragenin than you do in
your oat milk?
Absolutely Still, I don't thinkI want any part of it.
(38:13):
So, after they injected theserats with this caragenin
substance and they witnessedthat there was pain and
inflammation, they thenproceeded to stretch the back of
the rat and there's a diagramshowing you how.
It stretched the rat for 10minutes twice daily, and what
they found was that protocolreduced inflammation and
(38:34):
improved pain within two weeksof the caragenin injection.
A follow-up study to that studyshowed that the reduction of
inflammation was due to thereduction of pro-inflammatory
immune cells.
In the actual research, itbreaks down the different immune
cells and all of the differentinformation.
I don't think we need to gothat into the weeds for this.
(38:55):
Basically, what it's saying,though, is that there was a
reduction of inflammation, whichthey then concluded was a
reduction in pro-inflammatoryimmune cells.
So, as you know, I mostly workwith people who are managing a
pain issue, so inflammation is amajor concern, and probably
(39:17):
should be a major concern, bythe way, for every adult on the
planet, since inflammation is adirect cause of pretty much
every chronic illness that wehave.
So even though the data showsthat static stretching resolves
inflammation in rats injectedwith caragenin, that may feel
like wow, mandy, that is reallya wide bridge to cover here.
(39:40):
To me, reading research likethis is kind of a what is the
harm in recommending staticstretches to my clients, like,
yes, we don't have this data onhumans yet, but static
stretching feels really good, itis almost universally
(40:01):
well-tolerated, there is nocopay, there are no side effects
, or very few side effects,right.
So if it's possible that thisdata could transfer to humans,
why shouldn't I just kind of tryit out?
And so sometimes we useresearch, not because it's super
conclusive, but because there'sreally no harm in trying with
(40:23):
something like this and so manyof the things we do in this
profession or in this practice.
I want to talk about just onemore study.
This one will be brief.
This study showed thatstretching can help tendon
injuries to heal.
Tendon injuries to heal.
Now I remember learning in myteacher training years ago my
(40:46):
200 hour that tendons have noindependent blood supply and
therefore they never really healonce they're stretched.
They're stretched for life,right Like the credit card
analogy in the the Yin site.
So the complete guide to Yinyoga by Bernie Clark.
In fact I probably taught thismyself in my 200 hour trainings
(41:07):
that I have taught.
But this is a really revelatorypiece of evidence because it
showed, it concluded, thatdynamic uniaxial stretching
stimulates the biomechanicalconditions of natural tendons by
inducing tenogenicdifferentiation, alignment of
(41:28):
cells and extracellular matrix,and promotes tendon repair and
regeneration, promotes tendonrepair.
So we're all concerned aboutoverstretching, but it turns out
static stretching couldactually promote tendon repair
and regeneration and all ofthose other wonderful things too
(41:51):
, inducing tenogenicdifferentiation and lining cells
, ecm.
So I will give you the link tothis study, I promise, so you
can look at it yourself.
But I will say that what theyconcluded this was a meta
analysis, by the way.
So they looked at a bunch ofdifferent studies that were
looking at natural tendons andalso lab generated tendons.
(42:14):
The frequency of an effectiveprotocol and bioreactors is not
usually higher than 1 Hertz,which is a unit of frequency
equivalent to one event or cycleper second.
Okay, one Hertz and between 1and 12% strain.
So they strained the tendonbetween 1 and 12%.
(42:36):
That was the.
You know, depending on thestudy, some did 1%, some did 12,
some did 8, some 10, 6, somedid 3.
But all of them were somewhateffective in wound healing.
So you might be like, okay, howdoes that break down in my body?
What is?
1%, 12% feel like strain for atendon and it is extremely
(43:02):
difficult to conceptualize, tomeasure, and the fact is you're
never really going to know.
Have you strained yourhamstring, the proximal
hamstrings tendon?
6%, for example, in yourcaterpillar pose?
Like that's impossible, becausestretching a tendon is really
challenging when you're quotestretching, since the myofascia,
(43:24):
that's the muscle with itsfascia, takes up most of the
stress.
It's pretty stretchy and thenwhen you're stopped stretching
it, it's elastic and it comesback to shape.
So the myofascia is going totake up the primary, the largest
amount of the tension, and thenthere will be other structures
that can kind of take up some ofthe tension.
(43:45):
And only when the tensionreaches a sufficient level of
intensity will you actually bestretching your tendon, which is
why the best way to stretch atendon is actually resistance
training.
So I want to mention somethingabout this.
So, working with people wholive with chronic pain, who are
(44:07):
already a little plugged intothe yoga world, I encounter many
, many clients who have painwhich they attribute to over
stretching, specifically atendon attachment sites.
The ones that pop up the mostin yoga are the proximal
(44:32):
hamstrings tendons, so that'swhere your hamstrings attach to
your pelvis, at the sittingbones, the ischial tuberosities,
and a lot of your yogis.
Out there are like oh, I havethat pain.
Right, it's like an achy.
Sometimes it can be very sharp,almost a sick feeling.
It's like you just think I gotto stretch it, I have to stretch
(44:52):
it.
And then another one is thelateral hip.
That would be where the glutealtendon attaches, just below the
greater trochanter.
Those are the most common foryogis and even though and, by
the way, the feeling on that oneis the same just achy,
sometimes sharp, certainmovements really really bad,
(45:15):
wakes you up at night, verypainful when sitting, like those
are all the kind of things thathappen and these are known.
Potentially.
Obviously I can't diagnose youeither in person or over the
podcast, but these are symptomswhich are typically attributed
(45:37):
to a tendonopathy and eventhough stretching can reduce
inflammation and it canpotentially help with tendon
regeneration and repair,stretching is the very last
thing you should do for theseinjuries.
So I didn't feel like it wouldbe responsible for me to give
(45:57):
you all this great informationabout stretching, and if you
potentially have an issue in oneof these areas and you would
like help with it, you cancertainly reach out to me.
I do online coaching.
I've helped many, many peoplewith this problem or you can
find someone else who isqualified to help you with a
tendonopathy.
I have found that tendonopathyprotocol is really, really
(46:18):
helpful, even for people whohave never had a diagnosis of
tendonopathy.
So in this episode, you learnedthat stretching is so much more
complicated than you have beenled to believe and potentially
so much more beneficial than forjust range of motion and
flexibility.
(46:39):
I hope you've learned that itis not as simple as stretch it.
To lengthen it right Stretchingcould increase the cross
sectional area of your muscle,and I hope that you've also
learned that many of ourconcerns about overstretching
and injury are unfounded when wego down the evidence rabbit
(47:01):
hole.
You have also learned that diduration and dynamic stretching
can potentially potentially helpto resolve inflammation and to
speed up tissue healing.
So the question is how will youuse this information in your
teaching or practice?
At this moment, it might behelpful to just reflect a little
(47:24):
bit on that.
So here's a question for youWill you lean into the benefits
of stretching other thanflexibility?
Will you change your languagearound the postures, around
stretching, around the benefitsof stretching?
(47:47):
If I'm honest, I would say thatI would actually really love to
hear your responses to thesequestions.
I would love to hear if youhave any follow up questions for
me or if you have read researchthat you think would be an
interesting adjunct to whatwe've discussed here on the
(48:08):
podcast today.
So to do that, I wouldrecommend that you join my
private Facebook group.
It's called Movement forHealing.
It is a great place just to askme questions and pick my brain.
I'm going to leave a link in theshow notes, and here's the
(48:29):
other reason why you shoulddefinitely consider joining my
Facebook group.
I am going to put all of thelinks to the research which I
have discussed in the Movementfor Healing Facebook group.
I only get so many charactersin my show notes, so there's no
(48:54):
way I could include this in theshow notes.
So type in to Facebook,movement for Healing, or click
the link in the show notes, andthat will take you right there.
You will have to request to beallowed into the group and then,
once I approve you, you'll seeall of the articles right there.
(49:16):
All you have to do is click.
All of these are open accessarticles, so obviously I've only
scratched the surface here onhow evidence can enhance your
teaching and your personalpractice.
Next week, I am very, veryexcited to tell you about
research that is related toother important aspects of our
(49:39):
practice and many of us wouldsay the more important aspects
of our practice.
That would be nervous systemregulation, mindfulness,
attention, and I am going toapply these specifically to my
great passion, which is paincare.
Thank you so much for listeningand for your interest in
(50:01):
research literacy.
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