#72 - Tendons: from exercise adaptation to injury and rehabilitation, with Professor Michael Kjær

hello and welcome to inside exercise I'm Emeritus Professor Glenn McConnell from Victoria University in Australia and I'm also currently a Danish diabetes and ocine Academy visiting professor at the University of Copenhagen in Denmark the idea behind inside exercise is to bring to you the absolute who's who of exercise research so exercise physiology exercise metabolism and exercise in health and what I'm really wanting is for you to get your exercise information from the research experts rather than from influencers and indeed today to you Professor Michael K from the Department of clinical medicine at Biser Hospital in

Copenhagen who's also sociated with the University of Copenhagen in Denmark he has a really stellar and varied background he's a medical doctor who started off looking at glucose metabolism during exercise specifically what regulates liver glucose output during exercise he then moved into muscle and now is a world Authority on tendons so the effect of exercise on tendons what causes tendon injury whether you can prevent and treat tendon injuries so whether it's best to rest the tendon when it's injured or exercise it and we'll see that it's actually better to exercise it and whether any sort

of nutritional or drug treatments can improve tendon injuries I found it really interesting I think you will too so stick around I would of course prefer you to watch the whole chat and that way you'll get the full context but if you'd like to jump around a little bit you can look down the notes and then you'll see time stamps there so on YouTube you can go to the time which is in blue click on it and it will move to that section and on the other platforms you can just go down you can see

the times and you can move to them manually if you can do me a favor if you could like subscribe leave comments Etc that'll help get the message out because when people do searches the algorithm will tend to suggest inside exercise more if there's more likes subscribes comments Etc okay so enjoy the chat hi Michael how are you welcome to inside exercise thanks for coming on thank you very much I'm fine how are you yeah I'm good so you're why did you just explain so you're a medical doctor who's um also doing exercise research so

quite often I'm asking people you know were you a sportsperson first or a researcher first or whatever but you're actually a medical person so how did you actually get into this were you sort of interest in exercise and Sport and then thought I want to be a sports medicine doctor or did you do medicine or how did you end up doing what you did I I knew very early that I was very interested in exercise so I've been doing exercise my whole childhood and Adolescent period And when I had to decide whether what to study

I was actually dividing between studying exercise science or medicine and I chose medicine simply because I thought maybe there are some more options and I could I could still use the interest of exercise but but I knew from the first day of medical school that wherever I would end up then it would be something with exercise and that was really what made me feel if I had been become a psychiatrist I'd probably have done training in psychiatric patients so at that time I it was the exercise definitely first and then the choice of of occupation

came came after that and as as you probably know I ended up then specializing in Rheumatology because that was sort of close to sports medicine we don't have sort of a a big medical specialty called Sports Medicine in in Denmark despite the fact that I'm profess from sports medicine but but that was the entrance of it yeah but do you still not have a because in Australia we have sports medicine specialty is there still no sports medicine specialty in Denmark no no there's not I mean basically in Denmark so that Rheumatology covers also physical rehabilitation

and therefore they sort of feel that sports medicine is is on the non-surgical field that's the area and then of course if you're a surgeon you're an orthopedic surgeon and so so that's the way it is and and so so it also that's also why it started with uh during medical school that I was very interested in in beginning to go into to some kind of research um and um and there because I was uh active myself but I was also coaching on a high level European handball and then at a course there one of

the sort of top level courses there I had the Bine as a as a teacher and I heard about Ben saline and he he's not at the he was not at the medical school though he's medically educated but he was at the natural science faculty and um I asked him whether I could come and do some research because I was interested and curious about how the body is functioning I didn't study medicine necessarily to to sort of save mankind I studied actually to find out how things are going on in the human body and um

he was very open but he said to me at that time which was quite interesting maybe it was because he was generous or maybe it was because he didn't bother having me he said but you were from the medical school and then he said you should go to uh one of his colleagues a professor there who's called Henry galbo who's now retired because as bentin said he's the only one at the Medical Faculty who knows anything about medicine or about exercise in medicine and then I went over and knocked on the door and said I

would like to start doing some research and Henry galbo looked at me and said how far are you in the medical studies and I said I'm two year into medical studies and then he said then you haven't even finished your physiology course I said no because that's on the third year and then he said you can call me back when you've passed that exam and then I called him a year later and then he said oh we better find something for you to do so then he was my main supervisor during my PhD with bank

stin as the co-supervisor at that time so so it all sort of have Has Come Together there and the rest is history because then I stayed there doing a research that's an interesting background so did you even know that bank saltin was a big name at that time or in oh yeah I did I mean in in fact I actually had during during the the the third year of medical school I actually was able to buy one of the books about the first biochemistry and exercise meetings and had looked into that and I knew Bine

was was very much that time very much into the descriptive phes of a lot of exercises and then of course when I joined Henrik galo's lab I um I obviously went into the more metabolism and and hormonal Fields um so so that was my um well in Denmark it's the medic doctor of Medical Science but it would be like a PhD program for three years where I then studied primarily the sympathetic nervous system adrenaline or adrenaline and what was was going on during exercise how how much was regulated from the brain how much from the

muscle and also of course spent a lot of years looking at Del liiver glucose production what is really regulating the blood sugar during uh during exercise so those were sort of two two years at the at the um at the Medical Faculty here for research Department of physiology and then I spent a year as a postto at Stanford uh where I then got in touch with with Gerald Ren who's now who's now un fortunately dead but he was sort of the father of Syndrome X and metabolic syndrome and uh there we got to do some

exercise studies on type two diabetics and then after I came back and then I sort of took my own track there that's that's how I I knew you so during my PhD 1991 to 1995 there's all these papers I was doing glucose metabolism so there's all these papers obviously galbo uh Henrik Elbo and then Eric RoR who I had on four or five podcasts ago who who was also study with gbo and then your stuff and I couldn't believe your and it's funny I'm here in Copenhagen doing invasive studies with arctor now myself couldn't believe

the stuff you did with the liver you your epidurals and and um yeah epidural and then electrically stimulating the the leg muscles to contract to then see why just quick yeah and blocking blocking the Celia gangan was also very sort of challenging to do but but that's right we were trying to find out whether was the whether there was the the brain or the muscle that was really in control and and and the quick answer at the end was that that they're both important and depending on which hormones you're looking at uh it was uh

it was either the signals from the muscle or the central effort and it basically comes back to to the old story that that AOS C and linhard started with with the regulation of of both the circulation and heart rate and ventilation uh so it's funny there is a parallel there well I actually quote I don't know hopefully I'm quoting it properly but I quite often say how there's a lot of redundancy so something that's so important is you know glucose release from the liver there's redundancy so if you knock you know knock the muscles out

so there's no feedback you still have some glucose uptake if you if you knock the the signal from the brain you still get glucose output and it's this similar thing with um you know breathing so you just said heart rate and breathing you know you try and look at regulation of breathing and and it's like it's so important something else will kick in no I think I I think you're you're totally right I think it's a respiration physiologist Julius comro he wrote in one of the book The retrospectoscope where he says that if there is

an important thing to be taken care of in the human body there's probably more than one way to do it and that was exactly what we found out because there were all these nice um animal studies also from Eric rer and others which showed that if you manipulated a certain thing you could you could alter the the glucose uh production but but in humans whether we took the nerves Away by studying people who were liver transplanted or we did other acute changes we could still not get to the core of it and and and after

many years of studies there actually one of the last studies in that regards that I did together with David waserman from the US that was actually showing that it is the ratio between glucagon and Insulin that probably is a very important factor for the release of of sugar from the liver but um but that's how it is sometimes we we didn't we were not able to pick out sort of a magic factor that was really the one that that that nailed it but um but we were able I think to manipulate human models as as

much as we could at least so that's a good advertisement for my podcast as well because I've had David Bosman on the podcast and that was interesting as well because for a while there they'd say the glucon didn't really change much during exercise but it's because that was just the the systemic if you look at the you know portal V you see it did Etc so that's a good that's a good point and he was we met up because he was studying a lot in dogs and we were doing it in humans and then we

had a common uh post dog who then joined the lab here and we did a study together so that's yeah yeah and the redundancy thing is similar again with RoR because we I in the corridor the other day Eric RoR Yan meski and myself yanan's been on the podcast as well yogan and we're saying how if you look at regulation of glucose uptake in the muscle so in the mouth studies you know you look at knock out ampk and they still have normal glucose uptake pretty much I've done nitri oxide and knocked out OS and

they still have normal glucose uptake and then the studies showing you knock out camcas still so it's like there's just all this redundancy so makes it hard to study yeah that's I mean that's a very good point and and for many years you can say that that this has been a big discussion and also in relation to publication and I mean I don't no offense but but it's really difficult to get invasive human studies really published well because you can always argue in the humans that you have not knocked out it totally and a lot

of The Knockout things in humans would probably cause death in people if you did it but but but in in animals you can you can very often have a a clean cleaner model but the question is whether it really means something for for human and and and it's very very elegant that you can in different models show the importance of of a certain factor and that can be sort of uh you know a a proof that it it has an important role I think it's hypothesis creating and not necessarily solving the question because a lot

of studies even PE even studies which are published very very well from cellular or molecular or animal work cannot be reproduced in humans in fact there are studies where they tried in humans and they avoid putting it into the publication because that will deduct from the news of the public because it's actually it has is it is nice to know but it hasn't got a real importance for human body yeah that's why I think it's important to sort of try and look at both it's a bit hard but you know I've been doing it Eric

does it you do your human studies as much as you can you know we had one study we had seven catheters in each person F FAL vein both legs infusing microbubbles and looking at contrast andh ultrasound for muscle blood flow and insulin and glucose but then you do your knockout you think ah I think it's this enzyme and so then you knock it out but um anyway so this is very interesting so that that's how I got to know your work initially and so you've gone from liver and then why don't you tell us how

you moved uh you know that muscle there then into T yeah then it moved I mean the the quick the quick answer is then it moved a little bit um from from this uh this liver glucose production because then we wanted to find a model where maybe there was some more chronic changes and that got me into the the the area of spinal cord injury where I went to the New York to learn to electrically stimulate uh spinal cord patients who could then activate their muscle which they had no control over and that was sort

of the the entrance was the liver glucose production and hormonal production but it got me into um more into muscle changes and looking at what's actually happening in in muscle um muscle fiber changes contractility and for some years uh I I did some studies within that area and um and focused more on on muscle as such not necessarily on the metabolism but more on the structural changes hypertrophy atrophy what happened with the with the stimulation and in in different kinds and then at that time point I had finished my my specialty education and U become

became a chief physician and then they got they there was a possibility of making a professorship in sports medicine and that made a big change for me because then I really went into to all the sports injuries and that's where you know clinically that was really where my interest was and therefore I when I looked at the different injuries and we're going to talk about a little bit about muscle a little about tendon it became very clear to me that a lot of the textbooks on sports injuries were you know there were guidelines for what

to do but there were really really not many studies behind it uh it was very sort of pragmatic approach maybe there was a little bit of a clinical study but no one really dig into or dug into what was actually going on in the tissue and especially when we come to the connective tissue like tendon that that has been um and I mean we're we're we're coming from almost the same generation so we remember that that at studies at at conferences American College of sports medicine I mean there was maybe one small section on bone

and that was it and tendons and ligaments that was something for biomechanics people because that was very inert tissue and it was a tissue that either held or it was broken and uh you know muscle was much more Dynamic and that's where so so I I tried to go into the to the connective tissue especially tendon very early and uh I got I mean the the real story is that I got an invitation from physiological reviews to write about sympathetic control of metabolism and I wrote back to them and said I've actually shifted area and

I wanted to write of something else and they accepted that and that took me I think three quart three quarters of a year to do a a as a single author to do a physiological review paper with I think 700 references but it made me dig into the field of connective tissue and that's where it all started basically and then we were we were going into that there was at that time there was a a English researcher who is unfortunately dead today Michael reny who is interested in protein metabolism and he was actually sort of

discreetly also interested in connective tissue so when we started trying to find out that there was actually more going on in the connective tissue than we thought there was some Dynamics in the tissue it's not just an inert tissue then he became interested in some of the first studies we did on protein turnover and the change of tissue renewal of collagen was actually with him and we we stayed longterm friends until he he unfortunately passed away and that was actually the transition and from then on I kept my interest in muscle um also in the

hormones but mostly in in in muscle adaptation with uh with impatience bed rest uh training aging but a very very vital interest in the connective tissue of tendon so therefore it's very interesting that that some of my colleagues are actually catching up now on studying the my tendonous Junction because it all comes together and the things are actually connected in in a very nice way I think so so that's the the very short story of how how the transition took place and then it was more accepted in the sports medicine field rather than studying glucose

metabolis yeah it's interesting we had I had Abigail Macky on she was talking about the muscular tender disjunction and and I I because I haven't been working in the area I I was sort of still back in the the Dark Ages sort of thing not realizing there was so much going on and um even the the my the neuromuscular Junction and you know all this stuff that you just think you don't really sort of think about you just think all the messages just sent across and so and just sorry a quick one the the the

interesting small story there is actually that that some 20 years ago I was invited over to be a PhD opponent in Ireland at Abigail Mack's PhD and that was actually about connective tissue in muscle because very many people have looked at muscle but but connective tissue was like at that time so so um you want to get rid of it when you have to what you C when you do a biopsy exactly so what happened is that that that Abigail then came over for a post duck and then she stayed on here in Copenhagen and

recently as you know have became full professor and is really now looking into the myotendinous junction and also the neuromuscular interaction so so this is really an example that that the the whole connection between muscle contraction and the connective tissue has a wide range uh and and in this case it's it's been the the interface it's not just two tissues that meet by a coincidence so so I'm very happy for that that today that the connective tissue is much has much more attention that it had earlier I wanted to say that was pretty brave of

you during a physiological review on something that you you'd only sort of relatively recently moved into because I I it reminded me that there a colleague of mine I won't say his name in Australia but he got he got hassled by his university they said you only published like two papers last year but one of them was a physiological review single author it's like give me a break no that's a huge I mean it was it was it was reviewed and and it was I mean for me it was a check that that at least

you know I wasn't completely ignorant in the field but it was really a steep learning curve because to going into all the Matrix proteins coming from very sort of comfortable words in in glucose metabolism it was a big shift and and but the turnover thing and the tissue turnover is is still close to my heart and the methods are about the same it's just now more protein turnover than it is fat and and carbohydrate metabolism so that's interesting so I guess doing that you would have you know set yourself you could have 20 years of

research questions would have come out from doing that that review right to see you would have seen how little was known about a lot of lot of areas yeah but that that that's of that's of course exactly your your your point and and I've looked back to that a lot of times but but it's also a a a big risk and I I remember a lot of uh American especially American colleagues who said uh you know that's very stupid of you to going away from a field because now you've made your name in one field

you can't you know and and that's not been a thing for me it's it's more I had an interest and uh I don't care you know if and it could be a blind alley but uh but I think we've at least moved it a little bit in that area and I think for the for the clinicians it's extremely important and I mean it's you know that better than me also that there's a lot of hype on translational research and people want to combine Clinic with basic science but it's not easy and some people think translational

research is just identifying one molecule that could lead to another but but to have truly translational research requires that you get the clinicians to say hey um there there are things going on on the on a more detailed level and I think and and you know it also that that there is a tradition here in Denmark that a lot of us who are MDS are involved Eric R is one example there are several others B Clon and who are medical doctors but have stayed in in research um and collaborated the whole time with people with

other backgrounds whether it be from exercise physiology molecular biochemistry whatever and I think that is a very very fruitful thing and we we still have today uh my own lab but but also all the other labs here in Copenhagen have a mixture of people with different backgrounds and I think that's where the new ideas come up and I think it's an advantage okay it's obviously working here because I mean it's not a coincidence I'm here I guess and it's not a coincidence that um I've had I don't know seven or eight people on that are

from Copenhagen all right so this is a good uh background and just I know let's move on a bit but that was it was kind of Brave switching areas because you know when you go for Grants they obviously want you have a track record and so a track record but not in this but um obviously he did well so there's a good message there for people okay so why don't we think about um muscle so you know a lot of people were probably still thinking about like me you know maybe not thinking about the turnover

proteins and and so what what's actually going on in muscle how does it interact with the tendons you've obviously got the muscle the muscular tendon disjunction the tendon how do these things interact and and why do they get injured so okay why don't you start talking about muscle a lot of stuff there I guess yeah we can I mean the basically I mean overall you can say that there are there are of course like in any other case there are there are acute things and there are more chronic things and and and the acute things

clearly would be that you have some kind of rupture and that rupture could either be that the tendon will tear most people know about the killis tendon rupture that can happen H or it's what we would call a muscle strain injury which which predominantly happens in The myotendinous Junction so but also can h happen of course further up in in in the muscle but it's clear that that those are sort of very acute events and you're not in doubt when you have such an injury with sports that there is a sudden onset and even if

you're very motivated you cannot complete your 100 meter race or whatever it is and then there are the overuse injuries and those will not um attack the muscle they are predominantly in the tendon and the surrounding of tendon and over injuries has been sort of a you know you know people have not really realized what's going on there was a a belief for many years that overuse is maybe it's a small partial rupture like a stress fracture in in bone that maybe it's a small tear and it doesn't heal but there's more and more signs

that that's probably not the case especially in tendon and and is it a problem yeah it's a major problem because it's a you can say if you take top athletes for instance the the by far prominent reason for stopping career that's over your centuries could be Jumper's knee if it's around the knee it could be the Achilles tendon it could be in the shoulder could be in the elbow so so it's not something you just could uh could put away and if you're if you're a recreational athlete it will really is an annoying thing and

and if you're I remember a colleague from medical school who said he didn't want to become you know muscular scal it's not really interesting he wants something with with Neuroscience or Cardiology something real cute things you know where it really is life and death and he phon and he said the other thing is just a small thing and he founded me recently and now he's over 60 so he said yeah I have a problem in my knee I said you're not dying from it so it's not a big problem he said it's so annoying it

spoils my whole you know life quality and I said then we better look at it but it's just to say that that I think it's really something that that limits people's ability to do something and and to find out and that's really can say the overall uh theme for for why I've gone into this is I want to find out what is really causing it not necessarily sort of factors that could lead to it but what is actually going on what's the pathogenesis of it what is what comes first what comes next because because preferable

we would like to find a thermometer that could take you know that could tell you I have been running 10K today I'm a little bit s is it something I should be worried about in my achilles tendon or could I run tomorrow and that's really what we would like to get in that situation we are getting closer and having more and more sence also how to treat it but but if we could if we know what is happening and what the sequence is then we can also better jump in and say this is an early

stage this is a warning sign you should be take care of that so that that's a really overall question okay can I just ask the basics so like you said sometimes it's the muscle sometimes it's the muscular tenderness Junction sometimes it's tendon do we actually know why so you know I'm bit self-centered here but when I run and I we can talk about age later but just calf injuries right and I and I in signs it feels like it's in a different spot I hang on I thought it was there and now it's like over

here and and it feels know is it is that the muscle is that the is it muskers Junction and so do we actually know why um see me looking down at my c yeah sorry we could know why yeah yeah I mean you if you if you take the acute ones it's clearly a one loading that is too high compared to what it can tolerate and that could be sort of a special position or something the overuse is simply also too much load over too long time could either be intensity or just the the the

total volume but we don't know today who's actually registering it down in the muscle or the tendon and say hey now we're approaching that we can't do it but but the obvious thing biomechanically is of course that you have a muscle that clearly is shortening and you have a tendon that is lengthening and and there is a mismatch because the the muscle would like to contract very much and the tendon is is a little bit soft but it's also it takes some time for it it has visco elastic properties so we if you do a

contraction very fast you know you you you the tendon will appear relatively stiff and especially if you take the the the P the Patell tendon It's relatively stiff and that means that you have a a part of this unit that really has to withhold or withstand this muscle contraction and normally that's a beneficial thing because you don't want if you want to jump you don't want to have it take three seconds before you can jump you want the tendon to be stiff but you are loading it a lot in that situation so so why does

it happen because we do too much compar to what it consolidate yeah so even if it's like so with mine I used to be a distance Runner I to do a lot right but then then I'll go okay I'm going to try and get back into running and see if my calf goes I'll run one day 20 minutes fine next day three three days later 20 minutes fine next day 300 meters into it my calf goes so but I guess you would say that's just too much because you've gone from doing nothing to doing like

20 minutes 20 minutes you can you can say you can say that a lot of the exercise we do especially if if they're very very explosive and we want to want to run very explosive or jump that is not necessarily a good training for the connective tissue uh in itself it might be good for the muscle because you can biometric training and you want to have these explosive things but for the for the connective tissue it's not necessarily a good training it's a test of the equipment it's like taking a small car and trying to

drive through Europe with it it's not necessarily good for the motor or running America that in itself is probably not healthy but it's a test of whether you can do it so so so the point here is that there is something that is not cannot withstand these very uh many repetitions of explosive things and in your case if I don't know how how much over for an easy job yeah but but if you have I mean it sounds like especially if it's in the calf it could very be that you had a smaller muscle strain

injury and of course of course then what you do is you will then take some rest and then you'll start again and see how it works and maybe forgetting that the things will not just heal by itself I mean it does but it just takes much longer time so when you think you don't have pain and I can start again there is still a healing process that is by far not completed and and and sports people don't want to wait for several years until or for several months before they start again so that's the other

challenge is of course to say can we do a measurement saying that now you can be allowed to go for your run as you did before let's make sure we're clear because I was I was a bit I thought hang on a minute I had to think about that so make sure people are clear so muscles all muscles can do is shorten really they contract and shorten so you're saying while the muscle Contracting to shorten it's pulling on the tendon so the tendon stretching is that what you're saying y yeah that's just with noral concentric

contraction yeah yeah I mean if you of course if I mean if you do you can take the example you do an isometric contraction where the muscle by definition will will shorten a little bit it's just that your extremity doesn't move but but the tendon will elongate in that situation and then of course there are variations over that theme depending on your do content concentric or Ecentric contraction especially the Ecentric contractions because the the the the load on the muscle will be high then the load on the tendon will also be high and and I

mean the Ecentric contraction is very class iCal one let's say you if you play batminton for instance and you and you put your foot back and that's the the most frequent at least in Denmark reason for for rupturing your Achilles tendon you don't get a muscle injury you rupture your tendon and that's typically because it's a high load like this all right so make just make sure people are clear so concentrics where the muscle is shortening while it's Contracting Ecentric is Contracting but it's lengthening yeah so like you just showed if you're not on YouTube

yeah so if you're lifting a doing a bicep curve when you're lifting it it's concentric when you're lowering it and resisting gravity that's Ecentric and you're saying that's that's so with badminton they step back and their calf is Contracting while it's actually lengthening and the Achilles is lengthening yeah yeah yeah yeah and then and then the combination of of a little bit higher load we normally joke and say the most frequent cause for rupturing your aillis tendon in badminton is a 45y old slightly overweight men so who who still in their play exactly as they

did when they were 20 they're be becoming a little bit more heavy and they're done not in the shape that they were before and that's also the explanation why why sometimes in running recreational Runners that they think they can run the same as earlier but they forget that they're not in the same shape they might also have put on some kilos compared to earlier and that adding up for many kilometers of course plays a role that's the thing because I do these 20-minute runs and then I think okay well no why I'm getting injured because

I'm 30 years 20 years older or something and I'm 10 kilos heavier and I'm surprised that you know something's going wrong okay so if we just think again so I used to think of the muscle as you know and you talking about the connective tissue so you got the connective tissue throughout the muscle and then it sort of tapers down and then becomes a tendon but when I see when I see um you know presentations by abigal macki and things it doesn't look like that at all it sort of goes muscle bang and then tendon

so is that not actually what happens is that not what I that that is still that is still I would say debatable and I it's definitely so that we can't just see that the the tendon goes on and then splits out to the intramuscular connective tissue but it's probably not either correct that it's just sort of stops and then there starts a whole new thing so so a lot of people in in uh in the fapy area there are a lot of common beliefs that basically it's one long tendon there's just some muscle fibers in

between at some spots and that's probably not exactly the case and and especially Rick Liber in the US has done a lot of good studies on looking into this it's probably a mixture because you have to use the intramuscular connective tissue because in contrast I mean in in muscle the single muscle cell doesn't go from one end of the muscle to the other they have there are longer fibers there are shorter fibers but they need the U the connective tissue between the muscle fibers really to transmit the force in the in the tendon and we've

shown that both in the patella and the achillis tendon human that there the fibro the the smallest component or functional component of the tendon the fibro actually goes from one end of the F of the tendon to the other and that means if you've cut half of your tendon you have half the force there's no help between these fibral they are they are lumped together in bundles or facies but but in essence they are going from one end to the other and that's a big difference in this uh in this situation and in the muscle

also the connective tissue has a a shifting Arrangement so so I think neither we can say that it's just tendon that goes on neither can we say that it stops and then there's no more connective tissue because there is and and Abigail has shown and you probably talked about that in that podcast that at the end of the muscle before it comes to the Mendon Junction already these muscle cells begin begin to have different qualities as they go closer to the tendon and probably the same is the case within the tendon that there's a big

difference of whether the tendon is at the insertion of the bone or it's up there where the muscle starts that makes sense have you seen Brian Clancy is it Clancy he he gave a talk here he was talking about how muscle fibers even don't just go the whole way along they sort of they split in things so I guess there's a whole lot going on and are you saying with tendons that some of them split or that or they you just saying that they go the whole way along yeah the the F the fiber is

the smallest unit are going from one end to the other so so that means that there are and and and if we talk about overuse injuries in the tendon and I'm just jumping quickly here but if we talk about those there is no good evidence that people have been able in human models to see that there is a discontinuation of these fibos so what I'm basically saying is when you have an overuse injury and this is not that it happened this afternoon but something that comes gradually where you begin to be a little bit sore

in your tendons after you begin to have when you start running it gets a little bit better then it comes again and at the end you have pain all the time and we cannot in those situations we can see changes inside the tendon but we cannot see a discontinuation of these fibros so I think the tendonopathy uh or the overuse injury in tendon is not so much a a rupture or discontinuation it's rather something that is added on and fills up spaces in there and therefore the tendon swells and attracts water and that becomes then

s so so so there is there is a a a mismatch there in terms of what happens in in the tendon and what normally happens in the muscle and the sore muscle doesn't matter so much that that goes that will that will go back to normal situation in muscle you only have to worry about things that occur like this U as an acute thing sorry just clarify that again um I'm just saying I'm just saying that yeah if you if you look at a tendon you can have an acute injury which is of course a

rupture or a partial rupture or you have overuse injury where it begins to be more and more sore it has more and more pain in the muscle in the muscle you have either the acute injury or it's just a little bit overload from training so if you been out running and you're a little bit sore in your muscle you shouldn't take that very serious because that's more like a soreness uh and that is just the late onset muscle soreness and and will be better but you can actually so back to me sorry it's about me

of course with my calf I know I know because it's up high in the in the head you know the head is is signs I feel like I'll just be running and I just feel a bit of a tear and then I'm like limping and sometimes it ends up like black the next couple days or whatever so it's bleeding in there that can't be the tendon right it's higher up no no no and you're saying don't worry about obviously I have to worry about it right but um you're saying that won't become a chronic thing

is that what you're saying what are you saying no I'm saying I'm saying I'm saying that you have probably as from what I hear you probably have a small it started probably with a smaller muscle injury um that would be my guess but of course if there is a bleeding then you are tearing some of the vessels that are inside the muscle and that is definitely not in the tendon there is a little bit of blood flow in the tendon exactly there's not much blood there so so so it's probably a a a recurrent small

rupture of a part of your muscle that doesn't have it so so good and there some Scar Tissue probably also yeah exactly Scar Tissue yeah so that's the thing because I wasn't sure I thought you were saying like if you do an acute muscle injury don't worry about it it won't become a chronic thing it not I wasn't saying that I was just saying that acute muscle injury is a real injury if you just have been out running and you feel sore and you have no history of acute muscle injury then it's just because you

overdid something with a muscle that was maybe not uh trained enough or or not strong enough so so no no no h you definitely and this is a this is an very interesting aspect of muscle injury is that no matter how well you recover uh the it takes some time for the connective tissue really to recover in the muscle and and there is reason to believe that like on the skin if you have a a wound on the skin uh a traumatic wound there will be some scar tissue and there probably there will also be

some Scar Tissue it's it's it's only when it was basically before you were born that that the muscle totally heals up and you cannot see that beenin anything so so there will be some scar tissue in there it will never go back exactly to place it was before well that's what I re because you I was start talking about my own C but if you here you could feel it's like a lump on there it's like all right so if we go back to the ten okay but just another thing there what determines why so

in that situation why that the muscle goes versus the muscular tenderness versus the tendon do you know is it the forces is it because it's concent Centric do you know that's that that's still that's still a tricky question it's something with the forces of course but but it can also be I mean if you take the calf you have this sort of delicate balance between your Sol and your gastrus the two major muscles there and they are both contributing to going down into the to the Achilles tendon if if you look at some of the

people who who ruptured their achillis tendon for instance the classical the classical small picture of of David Beckham rupturing it it wasn't very a high load he was just turning and he was in very well good shape so so in some ways we cannot EX describe it but there there will be a bigger load on one of the things than than on the other um and especially these very quick Ecentric um stop stopping movements that will probably hit the tendon very hard whereas if you're in a a constant activity where there is Ecentric contraction also

like jumping or running fast um that will then be the my tendonous Junction more but but it's a good point it's not possible to say exactly where you will have the injury if you get one it is weird isn't it because you as you said with David Beckham but same there's a guy Justin Marshall so we just had the Rugby World Cup and I love the I was born in New Zealand so I was going be the All Blacks and they lost but anyway um but anyway classic he was just running to score a try

you know so I don't know if you know rugby but just just running he was you all day every day running and he just suddenly like 5 meters from the tri line he R it's total ky's just coruption you know nothing it wasn't changing direction nothing so it must be a bit hard you said you want to get to the point of sticking a thermometer or making some decision that's very that's very strange and we we I mean I I I I actually saw that one also um and uh um because I was in South

Africa recently I followed this this world cup there so no no we won't um but uh but it's clear that that there are situations where people probably should not have taken the Sprint or should not have run but we just don't know it and and you it's a very very well taken point we also have some track and field people where you are surprised that it happens in the tendon where you think why was that during a warmup period with things they've done a thousand times before so yeah so you mentioned about that thing about

uh how tendon sometimes can warm up and feel better do you know what's going on there so you'll think I I you know I don't my my k does feel that good or whatever and then you start running feels better the the the the research so far what we have of information is that that if we look at the things that occur early in in this overuse injury situation then it looks like that one of the early things that happens is a an accumulation of water in the tendon so it simply swells exactly where the

water is we don't know but what we know is that there are some molecules that are more prominent uh in that situation the there are some glycosaminoglycans from the protog glycan complex but it doesn't matter so much what they are called but it's more substances that have both a hydrophilic but also an osmotic effect and that means it can attract water and we've seen some some observations in top athletes where they have pain in the achillis tendon but it's still not really swollen not so to the extent that you can see it on ultrasound or

feel it or MRI but you can with some MRI techniques see that there is some water accumulation locally and they're also sore so the first thing that happens when you are overusing an a tendon Achilles tendon for instance is that it it's not painful when you run but if I palpate it or if you palpate it yourself you sore and you might also have a little bit of mourning stiffness soreness that's the beginning and that's probably and I it's not solid proof yet but it's probably so that that is the water accumulating in there and

and that's the first thing that happens and once the water accumulation becomes bigger the tendon becomes more swollen and it's like if you inject it forcefully water into it it will also be painful and that's then painful when you use the tendon and I think what happens in the early phase is that this water is not very strictly bound it's maybe sort of more like a swelling thing so once you warm it up or at least use the tendon or it could be stretching exercises maybe you can squeeze some of that water out in the

beginning the problem is once you've done your run it will come back again or you could also you could argue that just doing a massage of the tendon could probably help it in the beginning when it's not so severe then at the later stage when you've had it for let's say a month or two month then it begins to be some ingrowth of maybe some more vessels maybe some nerves that are coming in so that really contains also some some pain sensing uh thing and then the begins to come a tissue change so so we

can see that new formation of collagen there is a normal formation of collagen constantly but an excess formation of it doesn't come until two to three months into to the phase of overuse so so I think the early stage is that you have a little bit bit of more water accumulation and then some of the other tissue changes come later on and it's it's also from some of the studies we've done pretty clear that if you have an overuse injury for instance in the Achilles tendon and you had it for a a month for instance

a shorter period of time then you're are much faster back again than if you had it for three to four month and the the explanation is most likely that in the early phase it's reversible water accumulation and in the later stage you begin to have some structural changes and it will take exactly and it will take longer time so so if I mean it's also sometimes a common myth that you can rupture your tendon because you have pain in it and there's no sign that this is the case so it's not that you should be

worried that you rupture the tendon just because it's a little painful but what you can say to people is if you train on with pain in your achillas tendon you can do so but be aware that the the longer time you train with it in a painful situation it will take you longer to come back and that's important for some people who are in the competitive season they want have two more matches you can do so but be aware that it will take you longer time and if you trained with very painful things and a

lot of basket and volleyball players have constantly pain around the knee because they have jumpers knee as we call it the Patel attendant which is affected and if they train with that pain for a long time there's some data that indicate that they will also keep that pain for very very long time uh after that so to bring it together so you were saying earlier that that basically it sounds like early on when you've got a tendon sort s tendon if you biopsy that you'll find it's just the normal tendon structure and that tendon structure

even later as you get worse if you keep training on it and it's sore that original structure won't change it's more that you're laying down new things and pain receptors yeah therefore and therefore in the beginning it will be just water so it will just the distance between the fle will just be a little bit bigger and that can be shown and then in the later stage you can see that you have some some some there's some new connective tissue coming in and that of course if you take a biopsy there it will look a

little bit more Disturbed but but the main fibers or the fibros they are still there it's just in between those there will be some some changes and and that of course can take some time before that can be let's say replaced or at least be normalized again sorry but you're saying within the original core you have stuff laid down not just on the outside no not just on the outside and that was also sort of a question that's been around for a long time is it only in the outside that things are happening no we

we cannot see any big difference in the Dynamics what of what's going on in the tendon whether you're on the surface or you're in the middle of the tendon and and and our me our measurements show that you have a turnover in the tendon but it's not in the entire tendon so most likely and there was several studies showing that that most likely you have a dynamic renewal of the tissue while you are growing and once you're 16 17 you're basically left with the tendon that you're going to live with the rest of your life

and in that in that tendon around maybe 5% of of the The Matrix proteins which is dominated by collagen will be turned over maybe in a Cadian fashion that's what we're trying to prove right now but there are some indications that you have a homeostatic circadian rhythm where you actually like when you use the classroom and it's dirty and somebody comes and cleans it up and then it looks nice next morning so there is some kind of well not renewal but sort of a a homeostasis of the dynamic part and those Dynamic parts are probably

the one where you then accumulate fragments of uh proteins that then can attract water and that's the ca for the difference between a normal training if you then run 10K two days in a row you will accumulate a little bit of water and that becomes worse and worse so so that's where we are right now in in in understanding what's going on in the tendon so it's more Dynamic than we thought 20 years ago it's interesting is it all fits together as well so in muscle you've got muscle turnover you've got autophagy you've got mitophagy

and you know we know that's actually important to be breaking down the mitochondria and turning it over and if you end up with with old bits that aren't removed properly it causes problems same thing the tendon yeah you're saying you want to be turning it over sure sure I mean especially I think a few years ago we looked at that and autophagy seems also to be a very important role to keeping this thing going right now blood blood we touched on blood flow there isn't much blood flow at all in tendons is that right so

yeah that's right that's right but but there is water uhuh yeah but there there there there are some vessels in the tendon it's just compared to the muscle it's much less and there is also a rise in the flow in the tendon with exercise uh and that can be shown but it's just at a much large smaller scale but but the whole idea and this is really where we don't know enough in the clinic we use a ultrasound and then we have sort of measurement with Doppler to see whether there is an increased flow in

the tendon but that really just measures that there is more blood in there so we really don't know whether there are more vessels or is just the dilation of the vessels that are there some studies show that you with training you are increasing your stimulation of substances that will make new vessels or NE vascularization but we don't really know what is happening in humans and the interesting thing is that we use this sign with with too much blood flow and hypervascularization as a diagnostic sign for having an overuse but if you take Elite athletes a

lot of them have a lot of blood flow and you find the same thing but they never had pain so so there is maybe a correlation and it's also so that if if top athletes have a lot of these changes with a lot of flow they're more prone to get problems down the road but a lot of them don't get it so it's not really a good prognostic sign because that could have been the thermometer which you say okay if I can see some more blood vessels coming now you should hold the horses and and

not run so much but but unfortunately it could at this time Point uh I mean I don't want to be too definitive but it looks more like the the blood flow is a kind of an innocent bystander that like you get more vessels when you train maybe you also get more vessels when you in the tendon when you train and then if you then have an overuse injury and you have fluid coming in you have some changes in the tissue then you might form more vessels but it's it and it's not necessarily a good marker

for what's wrong it's kind of like with the na the back you know if you scan people's knees and backs you'll find something it doesn't mean it's what's causing the pain or or whatever but you're saying so they have more blood flow more blood vessels uh basil you're saying just at rest yeah yeah at rest and I mean and basically with there's no really good technique so far to to to see how many vessels there are I mean we basically just measure how much blood is coming through and then we're currently looking into that to

see whether we can see if it's more vessels uh um when you have tendonopathy so yeah okay so with training is it does it depend on if it's endurance or strength I mean so with strength training when people get hypertrophy do they get a thicker tendon as well as a normal response to training they they they they do so if they've trained for a long time and probably if they've been training while they were also growing we've we've looked at people who who have who do asymetric sports like fencing or batminton where you have one

leg favorable in front and you can see that not only is the muscle a little bit thicker on that side but the tendon is also but we've tried to train people for nine month naive Runners and they didn't get big attendance but but if you look at people who are volleyball players they have thicker tendance than kayak rowers in the Achilles tendon for instance so so so the the quick question the quick answer is yes it will adapt to a certain extent but if you take adult people that's probably very very very little adaptation in

in that sense but but it could still make an adaptation that what we can see that in train people there is a little bit of a higher turnover so the the small portion that is actually turning over is actually turning over faster we don't know exactly how much exercise you need to do but what we do know is if you put people to bed for two weeks or take one leg and immobilize it you can see that this turnover circadian turnover is going totally to zero so basically the reason why we don't recommend just rest

is that you're pretty sure that everything goes to zero and it's almost like that you you you just you haven't just stopped the car you've also turned up the engine so so you have sort of to to Kickstart the whole thing again when you then start and that's probably one of the reasons why people who just use rest as a treatment they will then have problems when they start again because also all you know regenerative processes also go slower uh if you don't do some kind of exercise oh that's interesting all right now I know

we've been ailles Centric and I'm going to keep doing being Achilles Centric unfortunately um so yeah the classic thing I guess is if you have a carf injury uh so Achilles well let's talk about so so Achilles tendon right part of you is telling you to to rest part of you is telling you to to keep moving at least walking and part of you is is thinking especially since I saw one of your talks a few years ago is maybe I should train the crap out of it um because I'll tell you I I got

a friend right Richard there you go Richard Sagi my mate now he told me years and years ago he had all these Achilles problems from running right and and he he' heard someone say that that they had an Achilles problem and they wouldn't operate they said operate on my achilles they wouldn't operate on it it's like and it just kept going for months and months and months wouldn't go away got frustrated and said okay you know what I'm going to do I'm going to do c raisers really hard C raisers until my achilles just ruptures

and then they'll have to go in there and operate on it okay so what he did is he's really hard you probably he the really really hard car phasers and it didn't rupture it got better right and then that made sense to when I saw your talk because you said when you've got a chronic Achilles problem then you actually go in there and cut cut it and it's like it fires it up again or something so just my my very I'm sure you'll give a proper explanation is that that it's become so chronic it's almost

become like normal and and the and it's not getting fixed and then if you stress the crap out of it then you have this infiltration of you know and you start to fix it so whether it's sticking a fork in there or no but it's the the the point here is that you need mechanical loading and you do it with heavy slow resistance training because there you have a a loading of the tendon it's not enough just to do stretching but you have to do uh loading of it but it's control loading it's not the

Ecentric component there's no plyometric component where you sort of jump or something it's a a constant sort of uh a little bit concentric and Ecentric but heavy slow resistance training and and more recently we've also shown that even at lower loads because you said you have to beat the hell out of it but but you can also at lower loads even at 60% 50% of what you can lift one time which is lower than you normally would use for for muscle growth there you can also see an effect so there's no doubt that this controlled

loading of it is a good thing and I think it's because the turnover rate is going up in that portion of it that can be uh turned over H and that is probably what is what is happening there um whereas what causes the pain and why this person has is is all these Landing things or or in running or jumping and and that in itself doesn't make it go away so so you you stimulate something down there that maybe only exercise can stimulate because we have not found any drug or any injectable things that are

equally good uh to make a quick fix and I think that's that's one of the lessons from both muscle injury and also tendon injury is that it doesn't look like that any pharmacological agent can replace the use of the muscle and tendon it might be that some of the things can help but but it's not in itself a magic thing it's like everything with glucose metabolism whatever it is it always ends up generally that exercise is the best thing to do but so you're saying though that this person that's got this chronic you know he's

a distance Runner he's got this chronic accles problem so my mate Richard had the same thing you know he just thought okay I'll just do it feels wrong but I'll just do really hard and you're saying you don't have to do really hard but anyway car phrases and you know you feel like it's going to make it worse because your Achilles hurts but it actually gets better yeah but but it's nothing to do with firing it up so I had this rudimentary thing in my head that because it's so chronic you know we're talking about

months years that it's almost become the new norm and then you've got to do something different to activate it is that is that just my that that that could be a point but I mean you have another point is that there is probably some new formation of of tissue not scarlike or whatever we should say but an excess amount of some Matrix proteins in there that fills up and if you if you take an MRI or you take an ultrasound you can see something is not normal there and and the the surgical approach would of

course be let's remove that and some people who go through operations get better because you remove something that is in there and you basically then create a new healing and that can be good but but but there is not a good evidence that treatment of tendonopathy with surgery really is the drug of choice but but you know story-wise or case study wise I can tell you that in some tendons where we took tendon biopsy like you take muscle biopsies and put in a very small needle to take a little bit of tissue out some of

the people who had problems for a long time they actually said that after the biopsy it was better so maybe we were down there sort of searing up that the whole thing can start all over again and that that might be that in some cases it's really it's too it's irreversible it's you have so much guard tissue down there so even if you do very nice heavy you know resistance training you cannot get rid of it but um but that's that's still to be to be solved why why this would help but but certainly you

shouldn't just because you have pain in attendant if it's an overuse injury not think that just surgery will help you yeah so so you would you would say then to people that if you've had a painful Achilles chronically overuse that you would suggest doing controlled um calf calf type raises yeah um and doesn't have to be really heavy even 50% what but you just do a lot of them every day yeah then you do a lot yeah yeah then yeah exactly how many would you tell people to do you know like 23 day the old

no but the old traditional exercises found first by by alfredson in Sweden and others both for patella and for Achilles they recommended that you did exercises maybe once a day or even twice a day uh and we've compared that to to just doing three times a week like you would normally do your strength training and it looks like that three times a week is enough and that would then be depending on your load of course but something like three times 10 repetitions like you would do with your strength training regimen really uh would be would

be enough in this situation we're currently looking into whether even less would do it because people always ask how little can I get away with uh and uh we will see how how it comes out so so so exercises that are not that far away from from the way you would do also with strength exercise so if you go down to 60% you maybe want to go up to 15 20 repetitions or something like that but but but just um just three times a week would be would be enough to get the effect over a

12 we period yeah and that would be enough to get to to get over like a chronic overuse injury yes yes there is a 70% effect both in the Achilles and the p the one thing that is still not solved I have to say though that is the challenge of the Achilles insertional problem so if your problem in the achillis tendon is down by the by the calcc bone or down by the heel it's another story because there can be a lot of other things taking place there but unfortunately those are not as frequent as

the mid portion problems in the achill all right so it sounds like you're saying because it used to be this thing about a you know lift yourself up with both feet in a c raise and then lower with one leg so it was like focusing on the Ecentric are you saying that's not really a big thing now just just up slowly con concentric down slowly Ecentric you don't have to be hanging off a step or you know whatever sure sure but it I mean the point was that when when it was found way back it

was actually people on a waiting list to have surgery done and the author also had a problem himself in the killers tendon and then they started doing these Ecentric contractions and there was a period where you were not really a proper uh uh person to treat these things if you couldn't say Ecentric and it was sort of a magic word and and the studies I've just referred to you with three times a week doing strength training and those are both for Achilles and for patella and they actually show that it probably is not the Ecentric

exercise that is the magic thing you can also get a long way with the with the concentric there are people out there who would favor isometric in the early phase when you have problems simply because it could then sort of squeeze out some of the things and and the tendon gets to move a little bit more um I think it's it's it probably also plays a role but I wouldn't be too much fixated on the type of contraction rather than just doing it do it exactly so we tend to complicate things so I think just

just stand there hold on to the wall lift yourself up slowly lift yourself down lower yourself and do it 10 times three days a week or something like that that you don't have to worry is it's concentric eent you're concentric on the way up Ecentric on the way down and you don't have to worry about sort of messing around is that right y all right now what about biomechanical again it's Achilles so what about biomechanics so obviously you know there's a lot to be a lot of people when you go to the Running Shop saying

you should buy this fancy B you know shoe and expensive shoe and and and you know have um reduce your pronation you know all these sort of bit pie do you have people looked at those sort of things for injuries yeah we have we haven't looked at it but I mean the the quick answer here is that that yes there is a correlation between some risk factors if you have a certain way of of Landing or you have a certain way of your anatomy in the foot you can show that there's a bigger risk of

having it but there are a lot of people who have some of these risk factors without having problems so if we find a person that has uh even if the person pronates a lot or do something and there's not a real problem then we would not fix it whereas the the shops sell you running shoes they would tell you that you will you will have problems if you don't get this or that or and and and and the real evidence behind uh running analysis I mean taking a video and saying you should have these exactly

these shoes is not very solid so so where I would say it plays a role is if somebody has a problem then of course if we then find that there is something which is very strange then we would say let's see if we can fix some of the things and I think especially the the problems with the Achilles tendon insertion there you really have to look into things like that and and and how how things and there you can manipulate but I think I think um I mean I probably the producers wouldn't like to hear

it but but I think there is a overselling of shoe equipment saying that for you it would be perfect if you did like that but of course if a person comes and say I always have these types of problems then I would do it and I remember way back we did some some blinded analysis of of people who are either patients or Elite Runners and we had at least two or three of the people from the national running team were were identified as they should probably have done something done because they they have a very

strange way of putting their foot in the ground so so one should also be be a little bit cautious of of overtreating so no exactly well you Michael Johnson's a classic you know he would lean back when he was running but he did well enough to win the 400 800 double I think it was so when you've said tendonopathy a few times it it's uh it just makes me think of a like a disease process is is what what is a definition of a tendonopathy well the tendonopathy is that you have a pain in relation

to the running that you have a thickening of the tendon and you have a palpatory soreness when you compress it as a medical doctor or if you can sometimes up in the shoulder you can that's the that's the definition you can say and then you can add things on and say you should be able to see something on ultrasound and MRI but that's basically a definition we don't take regularly biopsies out just to to diagnose what's uh what's wrong yeah okay and if someone comes along with with a thicken Achilles tendon and things or if

they've done actually I want to ask you the treatment again so you said not no sort of medicine or any supplement or anything does anything the exercise is the best thing it makes me think a few times it's come up with people who have said what about uh the classic you know rest ice compression elevation what about anti-inflammatories what about all these things do you know do you have any thoughts on those the the the the rest and ice and other things is is of course uh has some role especially compression has a role in

acute injuries you can say with a tendon rupture it doesn't matter so much because you have to find out how you want to fix it anyway but acute muscle injury is there of course you have it has a ro and it has been shown that you probably have a a quicker way back if you've done that but mostly with with acute muscle injuries it's much more important that you start your Rehabilitation early if you just wait one week with Rehabilitation it will take you three more weeks at the other end to come back so so

that's a point but but with the tendonopathy a lot of these things will not really help a lot we've looked at uh the use of anti-inflammatory medications so despite the fact you can you can find inflammatory components in there there neither in the early phase nor in The Chronic phase people have been able to demonstrate that all anti-inflammatory medication in regular doses will have any effect whatsoever sorry um but but there's no role there you can say glucocorticoid injection as an isolated treatment one should be very cautious uh because it doesn't really help in itself

it looks like that there are some tendons where a combination of strength training and not into the tendon but around the tendon with glucocorticoids maybe have an effect um and then there are also some other treatments um pled rich plasma which is used where you centrifuge your own blood and you take the rich plasma there with a lot of troyes has been shown to have absolutely no effect it's used it's it's given a lot but it's not having any effect high volume injection where you inject sine around the tendon can can have some effect if

it's especially if it's around the tendon there are problems and then people have tried with other drugs where they really have not shown very much effect the shock wve treatment has been used and shock wve treatment is very good if you have a calcification in the tendon but if you just have a regular tendon opathy with sring tendon you will have no effect but um of course if you have a shock wve treatment equipment you are more prone maybe to use it so um okay so it's either gonna have no effect or or maybe some

effect probably no effect but if you've got it you might as well use it it's been the shock wave has been shown in the original studies to be very efficient if you have a calcification and that was from the shoulder and if you have a calcification where you really can see that there is a a calcification area then it really has the effect that Shar wave has and can destroy that and then there are some laser treatment that Etc others but it's very very minor effect that has been shown there and you mentioned uh you've

mentioned collagen so a lot of people you know people always are interested in supplements you see all over the place supplement supplements and generally if you watch my podcast I'm generally saying don't take supplements you generally don't need them so I know some people go oh tendon's made of collagen therefore I should eat collagen what yeah it's I mean it's it's the same it's the same discussion as with muscle wear creatin supplementation or or with the cartilage with glucosamine supplementation because the substances are there should we then give them and there is very very sparse

evidence there are very few observations I know it's Advanced at some stages and we're we're actually currently in the study also on Elite athletes to look at whether it has an effect but but of course collagen is has to be broken down into the amino acids and then build up again so so you know you really should have a a lack of of am acids in order for me to think it would really be be helpful but it it sounds very appealing and I I don't think it and collagen I mean it's an important molecule

it's the most frequent molecule in the human body so normally we think when we are very muscle oriented we say Okay myosin Ain myosin are very important and if you're blood interested you will say hemoglobin and they are but collagen is like it's almost 2% of of the entire proteins so um because it's in the skin it's every it's the glue that holds it together but I I don't see at this point it's not a thing we we would recommend um it's not collagen may get broken down to its amino acids and then you need

to have DNA to RNA to to message RNA to actually say make more collagen to then put it together so it doesn't make sense in that regard I mean if I if I eat a tendon uh and it's not so that the fiber in there will will will will replace the other fiber I have exactly and and people can listen to Stu Phillips podcast where he says generally most people get enough protein in their diet anyway um now what is the best way to prevent tendon injury so I know you said so we're talking about

doing calf raises and things or the equivalent for other tendons um if you're injured but is it the same is is doing these you know 10 reps three days a week whatever will that help prevent no not not really I mean it's it's it's very important to uh to be in the shape that your sport will require and the most frequent cause for having overuse injury of the tendon is and we know that from people who are very systematic in their approach and write down what they've trained and the most the most uh risk the

highest risk factor to get it is a an increase a dramatic increase in your training amount in the last two to three months before and and I mean the the mystery is so that that that if you go out and train and you start running and we have a lot of people who we and worriers there are a lot of people who want to run a marathon and haven't tried it before and they then go out and run a lot and the first two three weeks as I talked about before you might get a little

bit of swallowing in attendant but not enough to have pain so people think it goes well and they Advance with several miles a week and then all of a sudden they say why did it happen this week I just trained the same as I did before but that's we can often see with a with a delay of 3 4 weeks and then go back and see okay something happened there it could also be that you've been let's say you've been running on soft surface and all of a sudden it it's getting colder so you run

on on on concrete uh and then people say hey I I did run exactly the same as before so so changes dramatic changes over time does make a difference and then of course all of us have an upper limit even if we're well Tred where we cannot tolerate more and unfortunately I mean we don't know exactly of there if there is any genetics behind it there are some people suggesting that there are some people who can resist more but but if I have three recreational Runners and they train a lot then one of them will

come with an overuse injury and he will say it's not fair because the two other ones didn't have it and they run exactly the same so so we all have a higher level and we know that from from Elite schools let's say on on volleyball in Norway where people are together and doing nothing but volleyball and some of those who actually are performing the best who can jump the highest who in the best shape they are actually very prone to get it simply because they train too much and what is too much unfortunately we don't

exactly know where it is but but there's no doubt that that respecting and that's what I say to Runners if you feel that you've been running a lot and your killis and if you squeeze it and feel that it's more it's more s s than it normally is then you're on a bad track and then you should probably reduce it a little bit or if you get more sore in the morning when you start the first step you feel like there is something then you're also on the wrong track and then you shouldn't go to

zero but you should reduce it a little bit and in explosive Sports we can very often have people train exactly the same amount of hours but they replace a lot of the jumping with this heavy slow resistance training instead so so a lot of the explosive things it's probably not the jump that is dangerous it's the landing of it which is which is very hard to theend yeah okay all right so so you suggest if people are in that position they should they should not necessarily um necessarily reduce what they're doing or just replace some

of it with that that more controlled car phras I mean that that would be a suggestion and and that's why that's why the the clinical experience is that that triathletes are in a very good situation because if they get a little bit overused by running for instance they will just swim a little bit more whereas if if you tell a a a very ftic Runner that he should bicycle or row a little more he would look at you and say you must be crazy because it's only running that is fun so so you know we

all have our preferences but but but shifting a lot of the people who can train a lot but don't have injuries is people who do very big variation in what they do uh if you do the same same same thing all the time and and I know from the track and field people a lot of the elite athletes in track and field have problems when they train too much on the track with with spikes uh and so so so there is something where we strengthen the tissue and train or build up and then there is

something where we test whether it can really resist it and if we if we test constantly it's like people say you can't just run a marathon every week I mean there are few people who can but but most people will at some point run into a problem even if their glycogen is built up again even if they should be ready because there's something that is not that doesn't tolerate that you do it that so it all comes comes to the load and how often and how if you're building it up so things like warming up

stretching so I had Christian thorborg I think you collaborate with him is that right sure yeah he was saying there isn't really good evidence for stretching things like that for pre uh for for prevention yeah no stretching and and it goes the same here stretching is a very good thing to do if you need to be flexible in your sports so a hurdle Runner should do flexibility training because you do get more flexible you do get a higher range of motion but we cannot show that it really decreases the amount or the risk for for

injury but of course if you have to perform in a certain way and you have to be flexible you should do that if you do strength training we know that you get less flexible and that means if you want to do strength training and maintain your flexibility you should also do that on the top so there's not really a big issue in selling people they should do strength training there but for some people it feels right and there are a lot of experiments where they've put warming up on people who normally didn't warm up and

it didn't influence their their their amount of of injuries on the contrary but people who normally do warm up if you took the warm up away from them they reported that they felt they had more injuries so so it might be also sort of a what you normally do and and it it it's sort of a a ritual you have to go through but but then of course the warmup instead of stretching but the warmup has of course we know that for performance it has an obvious role that that your muscle the temperature the contractility

will go up so so if you do a 100 meter run I would suggest to warm up but the injury you get is not necessarily from whether you w up or not yeah okay that makes sense I remember there was a distance Runner Robert D Castell he's a great distance runner for Australia in the 80s and I remember he was saying he couldn't even get within uh like two feet so 60 centimeters of touching his toes but he didn't care he didn't do you know he what do I care I'm a distance run I'm just

moving through this small range so as you say if you're not if you don't actually need that range then you don't need to try and get that range right um but all right so yeah there is something about the the connective tissue and the explosive things which is very puzzling because now you mention a famous runner we have a a famous Danish track and field person who back in the 70s won the European championship in in high jump and he was a very good decathlon very explosive he became a doctor later on and and he

told that because he was giving an interview he said that even at the age of 50 he could still he almost had the to Max his endurance capacity as before he could almost lift the same weights as he could before but if he went on the track field with spikes on and did a 100 meter fast run he would get an injury so so the explosive things he had to avoid this has been great I know you need need to finish up soon so how about we go to some of these Twitter questions so Fabian

can a fully torn this sounds a bit personal I think Fabian can a fully torn proximal hamstring tendon heel back to the Bone uh so what is the cellular mechanism if so is there anything a patient can do to make the formation of a neoton tendon more possible yeah if you if you have a muscle injury in the back and it's at the my tenderness Junction it will it will not require surgery but the the the example that he mentions a totally torn off tendon will actually require surgery and I don't think that should be

left un unoperated because it will not buy itself grow back at that stage okay okay so it doesn't just sort of attach to the I don't know other bits and pieces it just it ends up just blowing the it does but it it does attach in some way but it's not going to be as it was before and the the ability to do Sports will be limited okay just the thing about age so with age you know we we talk about you know the person you mentioned getting injured more often and whatever what actually happens

to the with age did I don't know if you said it earlier does there less turnover with it doesn't change very much and actually a lot of the changes with getting a little bit stiffer tendance with h is more related to not doing exercise than anything else if we take people who are very good shape when they're older there's not a big difference on the on the tendon whether it really is reduced in its tolerance before it breaks we really haven't been able to measure that much in humans but uh maybe there is a little

bit of reduction but on the other hand the muscles also get the get less strong so so it should go along with each other and and old people are not very prone to get tendon ruptures for instance and then you can say it's because they don't do exercise but but even those who do very much exercise uh Master athletes they're prone a little bit to get the muscle injuries but because they still do a lot of explosive but it's not very prominent that they get the tender ruptures so okay so they don't get changes like

you know you tend to lose elastin and things like that so I guess but you're saying tendon is mainly collagen there isn't much elastic in there is that right no there is a little bit in in there and it looks like that you your your tendon can can adapt a little bit better when you do when you use it and if you don't use it uh it tends to to become a little bit stiffer and that happens with age rather than because you don't do so much exercise like the loss of muscle yeah okay so

I had wind D on here and he was saying he's got some evidence that people with more muscle type two muscle fibers get more injuries now does that make sense I guess I guess that makes sense yeah it's just putting more strain or faster strain or something on the tendon it's probably the I mean the fast the fast movements there because the tendon has this visco elastic properties So the faster you you uh you make a movement in the muscle the less elasticity you will see in the tendon because it it when it those very

fast if it's visco elastic it will take some time before it elongates so so the more fast fibers you have the more explosive you are but maybe also the higher risk and this is a this is a very interesting sort of dilemma that actually the things that make you perform very well is actually also some of the things that make you go in a higher risk for for injuries um like a like a karate kicker if you're very good in relaxing your backside of the of the there your hamstrings for instance so you can kick

better so you don't get a co- contraction of the antagonist muscle you're also in a higher risk of getting injuries in the knee so so the more you train just to let the muscles activate for performance the more you also activate maybe the or you you you inhibit some of the muscles that are actually protective for the KNE for other things so I think there is a paradigm in in between this uh or dilemma between performance and the risk of getting injury okay Mark here has a question to what to what degree can the structural

changes in tendon seen in people with diabetes be reversed with resistance training and can the risk of tendonopathy be normalized is that a thing I I didn't wasn't aware of that yeah they they have a higher risk for for for tendon rupture and and there there are a lot of things that are not solved with the risk for tendon rupture and for tendon opathy there are also certain drugs anti-inflamm antibiotics the flu kinos where it's reported that people get uh get tendonopathy when they get those and there are a lot of things that we still

don't have an answer on yet why this is so but but diabetic people have a greater tendency to get uh tendon problems yes and uh we think that they have the same effect of doing strength training um but uh we are not pretty sure there I see my battery is almost running out on my phone so yeah okay all right so we're going to finish up soon if you don't mind where do you see the next big scientific or clinical breakthrough in tendon research clinical practice and in what populations athletes metabolic or rheumatological diseases yeah

I think I think the elite athletes they will just train more when we tell them what how to do it optimally I think the biggest Advance will be in the recreational um athletes or or people who do Recreational Sports because we will be more able to tell them what signals and what findings they should be worried about and where they by just small adjustments in the training can actually continue doing most of what that's that's what I what I strongly believe we can uh we can come to and I think we're getting there very soon

okay so also Mark again since there are ocin so these are these are proteins released from OS tissu of fat iines so releas from muscle hepatic kindes from so from liver just so the audience Etc do tendons also secrete molecules during exercise tendoc Kines he's calling them the quick question is we don't know there are much less cells in the tendon than there are in muscle and and it's also difficult to say whether a substance in the tendon should go abroad or or to some other tissue to do something but locally you can say that

what we do know is that there are in in tendon cells and that's published just last year in this circadian control thing that the the individual cells in the tendon release extracellular vesicles like they do in in in other tissues and those vesicles are signaling between the cells in the tendon and they are under circadian control so it's actually so that there is a a proof that there is a lot on the Circadian control and that's probably very important because that tells the rest of the tendon what is actually going on we also know that

when we measured with microdialysis some years ago that for instance il6 interlukin 6 that is known to be released from muscle is released to an enormous amount in from the tendon but what that means because it's it's it's it's a high amount but in the total in the total sum it's very little because the tendons are very small but if that has a role locally we don't know but it's a very tempting idea thanks for the suggestion yeah so with secan changes so if you got messed up by jet lag or whatever it could potentially

be affecting your tendon or it's a bit early to say that that's that is exactly what we're looking uh more into now and maybe also the question is it better to train in the morning than in the evening and what you know things like that but it's really difficult to make observation because you would think that people who have night shifts would that have more Ines but then again they are just a training uh when you do that but but it's a very good point that's interesting because I know I heard a talk about by

a sleep researcher uh Matthew Walker I think it is he was talking about if you don't sleep enough then you don't get amid you know that's associated with Alzheimer's uh removed because while you're sleeping it's removed so it can build up so might be the same with tendon you know we're getting that turnover if you're not seeping enough or your Cadian rhythms messed up and and the other the other point is that we know that growth hormone and igf-1 are very strong stimulators of the connective tissue and I mean even if you have an activation

of those with exercise the strongest activator of growth hormone is sleep so so that's really where you where you probably have a lot of the regenerative things uh the growth hormones by far the highest during night and that's a very strong stimulator of formation of collagen so that could be another issue yeah how about if we just before your phone dies can we just give a quick um take away messages possible so what do you want people to take away from this before unless you find eyes sure I think I think that the important uh

Point here is that sports injuries is an an an overuse of the tissue and that the connective tissue that we normally just feel as very inert as passive structures is more Dynamic than we think that uh constant exercise is really good for you it's about finding the balance between doing doing the exercise that is really stimulating the tissue and not misusing it and that balance we try to be better and better in trying to give good advices of how much is is good and how much is uh is too much right right thank you very

much so as usual exercise is good for us and even if you're having problems and you know it's your tendon for example it's still good to keep moving it and um maybe just don't overdo it so you know everything in moderation okay well thank you very much Michael thanks for coming good thanks okay bye bye see you I hope you enjoyed this podcast please like subscribe pass it on to your friends and colleagues check out the other podcasts thanks again