Dr. Trent Salo: Tendon Health

In this episode, Gabe Derman sits down with Trent Salo, founder of The Tendon Lab and a physical therapist, tendon researcher, and former professional basketball performance specialist.

Trent breaks down the different domains of tendon health and the value each provides when assessing and developing tendon capacity. The conversation explores tendon structure and function, load management, assessment, and the role of strength and power in tendon training.

Drawing from his experience in professional basketball and current work at The Tendon Lab, Trent shares how these principles can be applied across the continuum from rehabilitation to high-level performance, and where he sees tendon training and research heading in the future.

Gabe Derman (00:00)
Welcome back to the Keiser Human Performance Podcast. I'm your host, Gabe Derman. How lucky am I today? I'm with the great Dr. Trent Salo, founder of the Tendon Lab. Trent, how are you today?

Trent (00:12)
Yeah, good Gabe. Appreciate the opportunity, man.

Gabe Derman (00:14)
Absolutely. I gotta ask Traverse City, does it does it get any better than Northern Michigan this time of year?

Trent (00:23)
This time of year? No. Ask me in a few months, I'll

Gabe Derman (00:26)
Yeah.

Trent (00:26)
have a different answer.

Gabe Derman (00:28)
I mean what a what a great place. And obviously being up in Traverse City, man, like such an awesome place to be. So hopefully you're enjoying that late summer up there in Michigan. And for those listening, if you're if you aren't familiar with Trent, you should be. I'm just gonna do a quick background of his experience. Trent, correct me at any point, please. started with Detroit Pistons as a sport performance coordinator, working his way up to senior director of athletic performance for about a seven-year period. from there, he served as a VP for player health and performance for the Charlotte Hornets.

For beginning as an advisor and medical consultant, Detroit Tigers, and in some other areas as well. in June of last year, he founded and opened the tendon lab, a health and performance practice specializing in solutions for attendant health. and not to mention, he's also getting his PhD right now from the University of Copenhagen. Did I miss anything there?

Trent (01:17)
No, that's great. I so made me sound a lot better than what I am, so appreciate that.

Gabe Derman (01:18)
Nailed? All right.

Trent, the hardest question I may ask you today, I'm gonna ask you to be brutally honest. Where do you rank all time for assists for point guards at Calvin University?

Trent (01:38)
I'm just thankful they let me on the team. So I I don't

Gabe Derman (01:40)
Yeah.

Trent (01:40)
know that I cracked the leaderboard. I played good defense, passed the ball, and was in really good shape. So I I I maybe had assist the game.

Gabe Derman (01:46)
I was gonna say is that your game? I

is that your game are you a defensive guy?

Trent (01:51)
in high school I shot it every time. in college, just solid. Floor general, knew the plays, d tried to direct traffic. So yeah, l loved hoops, man. But my wife reminds me almost weekly now, that I have the body type for more of a soccer athlete than a basketball athlete. but yeah, l loved the game.

Gabe Derman (02:09)
It's not a bad thing as you, you know, as we age. That's a good, that's a solid physique. all right. So, Trent, I'm really excited about this conversation today. to be speaking with the expert in the tendon health space is certainly a great opportunity for myself to learn, but obviously all of our listeners. So let's just start from the beginning. Like I'm curious how this all began. What initially drew you towards tendons and tendon health.

Trent (02:34)
Sure. You know, I I think it just starts simply working in the game of basketball and and Gabe, you worked in hoops. So just the high prevalence of tendon injuries where depending on the the literature and the cohort, over twenty percent of basketball athletes have some form of patellar tendinopathy. And again, we can dive down the rabbit hole of how we're defining tendinopathy, et cetera, but that's besides the point. so a high prevalence of tendon injuries and hoops. I being a physical therapist, but primarily operating in the weight room.

I was like, man, we have all these players with tendon issues. I need to make sure that I upskill myself to make sure I understand what's really going on. So so that's the first first sort of interest in tendons. And then, you know, the the curiosity and my just desire to understand and figure out the world around me led me to continue to go down that path. And, you know, we had a couple challenging cases early on in my career in basketball that led to interactions with people that were much smarter than I.

And they expose me to kind of new ways of thinking, different technologies, that sort of thing. and then, you know, what I say or what I ask, I've learned this from a friend Scott Morrison, but he's basically saying that being wrong feels the same as being right until you find out that you're wrong. And so for me, it's important to continue to revisit my beliefs and thought process and making sure that I'm not just doing, you know, what I

Right on the internet or seeing social media with these athletes. It's going to the source for some of the research and really trying to upskill myself and understanding. just because again, athletes are trusting me with their care and their training and so you know, I need to make sure I deliver on that. So so yeah, it's it's I tell people it's a continuous pursuit of trying to understand tendons and you know, I just think that the the the more we can understand

or be a better scientist, we can identify these, you know, objective truths which allow you to to really better understand reality. And if you understand reality then you can manipulate manipulate or manage these variables intentionally. So yeah, the world is a complex place and team sport is very chaotic. And so if you can have some idea of how these variables go together, the the outcomes are typically tilted in your favor.

Gabe Derman (04:39)
Nice to hear the name drop of Scott Morrison, a friend of the podcast. so real really brilliant guy doing some great work with the Marlins And let's go right into that. I mean, you mentioned defining teninopathy. I I would open the floor for you to, you know, go ahead and let's define it's a great place to start for the conversation.

Trent (04:56)
Sure. I mean, when you look at tendinopathy, again there's there's some research papers that define it simply as pain in the tendon. There are others that define it as imaging or sonographic changes via ultrasounds at the tendon. There are others that define it that you have to have pain upon loading the tendon and pain upon palpation and pain after loading. so that's the challenging part and

you know, trying to be a better scientist in this new season of life for me, it's been frustrating at times, but also just eye opening and saying, gosh, a lot of the disagreements that we have likely stem from just not first operationally defining what we're referring to or talking about. So so my view of teninopathy it's it's load related. location is extremely important. palpation attenderness is is it kind of goes hand in hand with the location.

and then we we do see some structural change in tendinopathy, although you know structure doesn't necessarily need to change for somebody to get out of symptoms. So yeah, tendinopathy is a a a can of worms when you directly dive into it, but important to you know to f to to define that, you know, in addition to some of these other terms like tendon health, et cetera, that are often thrown around.

Gabe Derman (06:09)
It's gonna say my next question is going right into tendon health then. Would that just be the absence of pain? Obviously there's an aspect of function. So like to you, if you were to operationally define it, what does tendon health mean to you?

Trent (06:22)
you know, tendon health to me is sort of like a mental model, if you will, to help me make sense of things and and bucket or categorize things where this sort of stems from various frameworks. you know, the athletic injury framework where Judd Kalkobin back in twenty nineteen put together this holistic understanding of of overuse injury through, you know, concepts of load tolerance and load application, where I took that and sort of simplified into

Capacity versus demand and injury occurs when the demand exceeds the capacity of the tissue. And I bring that up because I then view tendon health as the capacity side of that equation. And tendon health is is is again it's a it's a multidimensional construct composed of domains that effectively define tissue capacity. it's it's it's what the tendon can handle right now and what the tendon can handle in the future.

And so again, a researcher out of Delaware, Carl and Silvernagel and some of her you postdoc students, Sean Hanlon, have come up with a few papers and looking at different domains and subgrouping those you know, athletes or clients within to certain domains. and so for me, just taking some of that work and iterating on it to make sense in my brain. But again, it's a way for me to try to bucket or really understand all the components or or or things or variables that go into the capacity of the tendon.

Gabe Derman (07:45)
Like we said, there injury occurs or pain occurs when we have demand that exceeds capacity, usually a a good precursor for injury. And then these different domains, what it can handle now and what it can handle in the future. So take us into that. What are some of those domains?

Trent (08:00)
Yeah, so there you know, I I've sort of boiled it down to four. so I I look at capacity or tendon health as comprising the structural domain, the mechanical property domain, the function domain, and then the systemic or you know, personal factors domain. symptoms and personal factors, depending on if you read some about Karen's research, she has a couple different ones, but I've just sort of combined them two into more of a you know, systemic

symptom personal factor domain that's sort of all encompass encompassing. So so yeah, structure, function, mechanical properties, and then your your fourth domain, which is that systemic or personal factor domain.

Gabe Derman (08:39)
Okay, let's begin with structure. What is tendon structure? How do you trend evaluate it?

Trent (08:50)
Structure's a fun one. for me, you know, structure is essentially your your internal tissue organization, the the alignment of the fibrils within the tendon, where you'll sometimes see the word morphology thrown around, which morphology is related. It's just the the gross geometry of the tendon, the cross-sectional area, the length, the thickness, etc. but structure, when I think of structure of a tendon, I'm thinking the alignment of the fibrills of the tendon. Are they aligned? Are they, you know, continuous, wavy? Are they

you know, like patchwork. and and there are various ways to assess structure the common imaging modalities such as MRI or ultrasound, where both are good for different reasons. But ultrasound really provides a detailed look under the hood of the tendon and being able to be a lot more granular in what we're looking at. Whereas an R I will pick up some of the larger issues, you know, the elephants in the room, if you will. So

So I I currently use ultrasound to assess tendon structure, both a grayscale, B mode, ultrasound, but then also ultrasound tissue characterization, which allows us to quantify the alignment of those fibrills. So again, my brain's fairly simple. So being able to see really cool colors after an ultrasound makes things a bit easier for me. And so yeah, using ultrasound tissue characterization and just regular B mode grayscale ultrasound to assess tendon structure.

Gabe Derman (10:04)
For U T C, I think I was listening to another podcast that you're on where you gave a really great analogy about maybe like a tree farm or so. Like for someone who maybe isn't as familiar, can you maybe provide that analogy or or share that analogy?

Trent (10:18)
Yeah, I I can't even remember where I came up with that one on the spot. I think that might have been Jake's podcast. But it yeah, it was it just made sense in my head at the time. And so w what we're measuring is if you think about the Achilles tendon as a rope, within that rope there are multiple hundreds, thousands of other smaller ropes all going in that same parallel direction. And what UTC measures is the stability or the alignment of those ropes.

And so I've taken it and basically given the analogy of the tree farm where if you have a tree farm where you have all these trees in a nice straight aligned row, where if you're walking through them, it's almost just like a path, you know, every five feet or so. And the the trees are really strong, really tall, very straight. That is the echotype one in UTC. And so echotype one correlates to the type one collagen in attendance. And so type one collagen is the good stuff, the strong stuff.

Again, the aligned trees, if you will. where type two, echo type two, the the you know the blue on UTC, if we're giving the tree farm analogy, we would say, okay, maybe you know the trees are waving back and forth. you know, that those fibrils, the collagen fibrils are a bit wavy. and so that would be the type two where maybe that occurs after a high bounce of loading, you run a marathon, you image before or after that marathon, you'll see an uptick in that type two. and then type three and type four, so type three.

Think about, you know, just starting the tree farm where you have all these young trees and they're just growing and they're kind of all over the place, a little bit like patchwork, if you will, but it's not not those nice aligned fibrils yet that the the type one is. and that's so again that's the type three or the red on on UTC and and the type four is just open field. So it's it's it's amorphous tissue. It's echo type four or black on UTC where, you know, there's there's no trees growing.

Just there's not much there. So so yeah, the tree farm analogy, it made sense in my head. hopefully I explained it okay right there. But again, it just comes back to the alignment of the fibrils. The more aligned, the stronger the tissue versus the wavy, discontinuous patchwork, that's where we can run into some problems.

Gabe Derman (12:23)
when did you start getting involved with UTC? When did you start gaining these skills and looking at graphs like an imaging? Like, you know, I believe you started as a strength conditioning coach, right? So at what point in your career it was like, this is a whole different world that I have not explored yet.

Trent (12:39)
It's funny, you know, in physical therapy school we learned that if you take a hundred people and you image them, image their low back off the street, depending on their age, most of them would be asymptomatic, but have some form of structural change on imaging. And I remember learning that in PT school and just latching onto it and saying imaging doesn't matter, you treat the woman, you treat the man, not the scan. And unfortunately in in elite sport, structure absolutely matters. It's one of the biggest risk factors for future injury.

And even though it doesn't need to normalize for somebody to get out of symptoms, pain is a little complex. but structure matters. And so early on in my career, we had a physio who we brought in as a consultant, introduced me to the technology, became almost a mentor or guide of mine to to teach me how to use the technology. We ended up purchasing s purchasing a unit, again, continuing to upskill myself, learning from people much smarter than I. and then having the opportunity after, you know, in this new season of life, after basketball, you know, I have my own system now. And so we

We uda utilize it both for the diagnostic piece but then also for serial scanning or monitoring tendon structure. so spent some time over in the Netherlands, which is where it's from, UTC imaging. So spent some time training over there and then continue just to learn from again the the super users who who again have a lot more reps at UTC than me, but you know, I'm I'm I'm getting there.

Gabe Derman (13:56)
I love it. domain number two, mechanical properties. What characteristics are

Trent (14:00)
Yeah.

Gabe Derman (14:01)
important to identify? What's important to you?

Trent (14:02)
Think about mechanical properties basically being stiffness, where I I I don't want to go down the you know equation of stiffness, even though it's kind of fun to think through. but what I want to get across is the second domain mechanical properties, think about stiffness or the resistance of deformation to the tendon. I think it's important to mention that stiffness is not just one number. We we often or I've often seen, you know, somebody do a hop test on a force plate, for example, and say, well, that athlete has a really stiff Achilles tendon.

Unfortunately, there's about four different layers of stiffness where you have this global stiffness, which is your your your leg or the vertical stiffness, you have your joint level stiffness, you have your muscle tendon unit stiffness, and then you have your tendon stiffness. And so all of them are important for varying degrees. But why mechanical properties or stiffness matters for a tendon are two reasons. The first one is health related. And so when you have pain in a tendon or you have pathology in a tendon, the

The amount of force required to strain it, it strains at that same level of force, is another way to say it. And so the the strain is what matters for a tendon. and the the strain increases at the same level of load when you have pathology in a tendon. It's it's it's again, it's becoming more compliant. That's the health side, but what we often see is these are these performance consequences.

Where I'd I'd give the analogy of it's trying to dribble a flat basketball. You could do it, but it's really hard and you have to work much harder and you just lack that pop, that explosiveness, if you will. And so I I had a D one lacrosse player in yesterday and had him doing just a single leg hop, just to try to elicit some symptoms and he just said, I don't have any pain,

Gabe Derman (15:47)
Right.

Trent (15:48)
but man, I feel like I'm jumping on a flat tire.

And again, it's that decrease in stiffness or that increased compliance that that we run into with a you know mechanical ch or mechanical property changes in pathology. So so yeah, that that's mechanical properties. You can you can measure it a variety of ways. you know, I d elastography, tensiometry are a couple different ways that you'll often see it done in a lab. I recently, maybe about a year ago, purchased the Mayaton Pro. I've since then sold it.

simply because it measures compressive stiffness. And so it basically applies a stimulus perpendicular to the tendon and measures the response of the tendon. it just it's not the same as tensile stiffness. So again, a whole nother rabbit hole if you will, but where the field is going is getting a better understanding of the force elongation curve of a tendon. So how how much force do you need to apply to a tendon for it to stretch a certain amount. And if it takes a lot of force to stretch it just a little bit,

Well, that's a good thing because typically that tendon is is more stiff or that means it's more stiff. a and stiffer athletes are are tend to be, you know, faster, can jump higher, change direction, that sort of thing. So can get messy, but again, just think of mechanical properties being more of like the stiffness of the tendon and that stiffness goes down when there is pathology in the area.

Gabe Derman (17:02)
Yeah, I say I play recreational basketball and I feel like I'm on a flat tire all the time. Maybe I'm just getting older. Maybe maybe I'm just hitting the limitations of my genetics, you know. so you you mentioned the analogy of dribbling a flat basketball. Is there ever a point at which the basketball was overinflated?

Trent (17:23)
Yes, but less common. And why I hesitate is because there there of course is this, you know, perfect amount, not perfect, but a a U shaped, if you will,

Gabe Derman (17:36)
Right.

Trent (17:36)
level of stiffness where if you have too stiff of a tendon, then that puts you at risk maybe of more muscle related injuries, where the tendon is so stiff but the muscle as a part of the muscle tendon unit just is unable to handle the demands. And

I anchor to the function of a tendon being a buffer. So it buffers muscle. And so again, there's some work out of Berlin, out of Germany, that that they're trying to identify the types of athletes that have a weak muscle and a stiff tendon. Or a strong tendon and a com or a strong muscle and a compliant tendon. And then they're bucketing these athletes based on that presentation to then give them a specific stimulus to say, hey, you have a a weak muscle but a stiff tendon. All right, let's do things that just

Strengthen your muscle and maybe not stiffen the tendon. So again, that might be a bit too granular, but I think that's maybe where we're heading. kind of danced around the question, but I I again I think too much too much of a good thing is a bad thing oftentimes. And so I I do think

Gabe Derman (18:32)
Mm, mm-hmm.

Trent (18:32)
we we we we absolutely can have maybe too stiff of a tendon. I just it's uncommon. we can almost just theorize it at the point, just given some of the limitations in in assessment.

Gabe Derman (18:41)
Sure.

tell me if this is an unfair question, if you were to look at a hundred individuals that have some sort of pathology or tendinopathy,

What percentage is identified as structure related versus mechanical properties? Or are they intertwined?

Trent (19:02)
Both. And the reason I said both is that if we look at the tensile capability of type one versus type three collagen, type three collagen is less tensile strong. And so you can it strains at a much easier level than the type one collagen. And so you could say therefore in a tendon that has more type three collagen for a variety of reasons, it's overloaded, etc., it's becoming less stiff.

obviously there's some involvement from the extracellular matrix, et cetera. But I I would say that stiffness is almost an outcome, if you will, of changes in structure. obviously there's some neuromuscular factors, et cetera, but it's it's oftentimes difficult to have one without the other, although of course there's some nuance.

Gabe Derman (19:45)
Okay, so we've covered structure, we've covered mechanical properties. Let's talk about that third domain you mentioned, which is symptoms and personal factors. How does that influence tendon health?

Trent (19:59)
I say that the I I've learned that the Achilles tendon is a litmus test for your overall health. And a lot of good literature coming out supporting your metabolic health. So the diabetes, the obesity, the the hypercholesterolemia, hyperlip hyperlipidemia, hypertension, all of those can impact your tendon. And why that is, it's essentially creating this inflammatory state or systemic inflammatory state.

That then can impact the recovery of a tendon. and so oftentimes in the athletic population, we see entry into this tendonopathic loop via overload, mechanical overload. But especially being in the private sector now, I've seen you know a few more general pop clients where a lot of them have you know, have some of these metabolic issues or they have

ankylosing spondylitis or rheumatoid arthritis or gout or some of these other systemic inflammatory conditions that impact their tendons. Why does that matter? Well, you you can't just give somebody heel raises and not worry about the rest if the primary reason they're having some of these tendon issues is more systemic, inflammatory, metabolic related than a mechanical overload related. so the yeah, that that's sort of the fourth one. Again, depending on the the the

cohort or population you work in, you may not see a lot of these, but I do think it's important to keep in mind, especially in, you know, there's one example in sport where we had a D1 volleyball player who had insertional tendon pain bilaterally and ended up being positive for HLAB27, which is just again an inflammatory marker that can cause some issues at the endhesis or insertion. So so again, not you know look for for for elephants, not zebras or whatever the saying is.

but it's important for I think everybody to understand that there can be tendon issues from more of like a metabolic entry point.

Gabe Derman (21:52)
That's fascinating because I'm sure at some point you got pretty granular with tendon tendon health, but all of a sudden it allowed you to zoom out with even a clearer picture you said an Achilles tendon is a good litmus test for overall health. I mean, I I think most practitioners, most you know, general population people would never think, Hey, how is this related to anything else going on in my body? I just have pain right here.

Trent (22:11)
Yep. So

I work pretty closely with a a a physician here, a medical doctor, and and we order blood work or he does, I can't, but he orders blood work for a lot of the clients that come in that we suspect some type of inflammatory disorder. And so again, we've learned a lot of this from rheumatologists from overseas. Paul Kerwin is a really good one. he's got a really cool analogy or or acronym called Screendom, which is just like skin colitis or Crohn's, relatives, eyes.

early morning stiffness, nails, and a few others. I can't remember off the top of my head. But anyways, just basically some of these things that you should look for in somebody that is presenting with something that just doesn't seem right. so

Gabe Derman (22:50)
Wow. Yeah, that's that that's really cool. And I think earlier you had mentioned if you were to take a hundred people off the street, you looked at low backs, you scanned low backs, you may see some sort of structural issue, let's say, and maybe they're asymptomatic. But even in my own experience, and I'm someone who actually had a low back pathology, L4, L5 disc herniation surgery, I've talked to a lot of people.

Who have experienced low back pain, especially those that like where it comes and goes, I have definitely, in my own experience, seen a strong, strong connection between emotional stress, work stress, social stress, and them becoming symptomatic during those times. It's amazing. Like, and then all of a sudden you see them a few weeks later and they're happy and everything's fine.

Right? No pain. Well, all of a sudden, you know, for me, I started asking, hey, what's going on in your life? You know, what what what are these other personal factors that are happening in your life? Because maybe, just maybe, like it'll give us some insight and shine a light on maybe why you're now just now experiencing that pain because the structural change maybe has always been there. maybe that herniation has always been there. It's just at certain times you start to feel that. So kind of maybe what you're alluding to there.

Trent (24:03)
Yeah, spot on. Spot on. I heard the analogy the other day where the environment in the body is kinda like the forest and the forest can be more dry or less dry. And if it is less dri or if it is if it is you know, drier out and Smokey the Bear has a high, you know, flag up saying high fire danger today, a small little spark can cause a huge forest fire. And so this these systemic these risk factors such as obesity, high cholesterol, stress, that sort of thing.

can cause the forest, quote unquote, the environment to be dry. And so therefore, even just the smallest little thing reaching down to pick up your kid lights the whole forest on fire. When in reality, if you didn't have all that other stress, et cetera, it's like, man, I could do that all day. So so that was recency bias, but I I just I just heard that and I was like, that makes a lot of sense just as far as the environment that's created.

Gabe Derman (24:53)
I think new kid has to be a huge one, like for low backs, right? And it's like of course like you're so stressed out, you should be stressed. You're sleeping less, right? Like you're up in the middle of the night. you're thinking about your family, you're thinking about financial stress, I'm a new parent myself, and you know, I'm cognizant of that, that it could just take one time of you bending over, but that is because the forest at that time is really dry. I love that analogy. That's great. I'm gonna start using that.

Smokey the Bear, I gotta remember that Smokey the Bear. Okay.

Trent (25:22)
Might be a northern Michigan thing, I don't know.

Gabe Derman (25:24)
no, no, I love it. I love it. Okay, so so far, just to recap, we covered structure, mechanical properties, symptoms, and personal factors. Number four, function. What does function mean to you?

Trent (25:39)
The tendon is a buffer to muscle, and that that's the function of it. And it's important to then assess the function of the muscle tendon unit. I've latched on to Lachlan James's strength classification system, where he basically looked at in in his literature that you know these these strength qualities, as we'll mention shortly, they share less than 50% of common variants.

So they're they're distinct physical qualities that they they need to be trained individually, you know, d depending on the relevance to the the athlete or the sport. and so those are you know, maximal you know, maximal isometric strength, reactive strength, heavy, max dynamic strength, fast max dynamic strength, and explosive strength. So again, it can big it be a little, you know, a a mouthful saying all of those, but you know, the

Gabe Derman (26:28)
Sure.

Trent (26:28)
ones that I really consider

are the the isometric, so maximal isometric strength, reactive strength, and explosive strength are some of the big three for me. and yeah, I mean we can we can dive in, I guess, from a an assessment perspective.

Gabe Derman (26:44)
Yeah, why? Like why

why why those three? We'll go to assessments in one second, but yeah, like why why those three? Why have those become really important to you?

Trent (26:53)
I think because I've primarily seen you know, I primarily see Achilles and patellar tendon clients, athletes, and with the Achilles, the Achilles, every step you take experiences three times your body weight in peak force. When you run, it experiences anywhere from six to twelve times peak force. And so I would say most humans, if they're able, walk, sometimes run and jump. And so regardless of the sport, etcetera.

I think everybody should have really, really strong calves or they should maximize their max isometric strength. so that's that's the first one. the the other one is the just the reactive strength. And so if we just look at somebody's ability, speaking specifically to athletics now, you know, there there is some correlation between somebody's ability to run, jump and cut and the reactive strength ability. so again, if you're in a sport that demands that, then I would say reactive strength is is important.

And I guess you know, the the third one for me is just the explosive strength. And where explosive strength and maximal isometric strength differ is just having a time constraint now. So you might be able to produce high levels of of of strength or high levels of peak force on an isometric test, but it takes you five seconds to get there. Well, unfortunately they they they you know stole the ball from you and are going in for a a layup or a dunk. And so adding a time constraint via the explosive strength,

i is is that that third one that I think is important. Now of course it depends on the context in the athlete, but for me

Gabe Derman (28:20)
Right.

Trent (28:20)
it's more of like a how high can you get that line on an isometric test? And then how quickly can you get to that point?

Gabe Derman (28:27)
If it's me, I'm going up for a dunk, but you maybe other people layups. so so do you have kind of like a go to battery of tests that you just automatically go to? Is it really individual specific? let's start to work through maybe some of those assessments that you're you know about to expand on.

Trent (28:44)
Sure. I think the easiest one for me is just to talk through the Achilles. I like the patellar tendon, and there's obviously some people who think the patellar tendon are just as important, but Achilles often elicits a visceral response sometimes. the test that I use for the Achilles or the muscle tendon unit triceps or calf complex. I s I view these these these you know first two qualities, the the strength endurance and neuromotor control, which we haven't quite talked about yet, but for the calf they're important.

we do a heel raise endurance test for that. And so we're basically seeing how many heel raises can you do on one leg to a one second up, one second down tempo before your technique breaks down, or you just tap out. And we're not just counting the repetitions, we're counting the excursion of the heel. And so there's a a free app that you can use that can track the lateral malleolus and how high it goes. And so you can get some some nice objective numbers on total work done, peak height, fatigue index, etc.

And so being able to produce force repeatedly, having good strength endurance is what we use the heel raise endurance test for. so that's that's one. The second one looking at the maximal isometric strength is just the seated single leg isometric test, which you commonly see done quite a bit. now my one disclaimer is the private sector budget for me, unfortunately, is a little different than the team side. And so

I would invest in isokinetics. It's getting easier. The price point's coming down a little bit, but would would love a humac and would look at isokinetic testing. But for now we look at maximal isometric strength in the the seated calf position for for that maximal isometric strength. And then from there we continue on to the we do a single leg CMJ and we do a single leg hop test. So the single leg CMJ just looks at dynamic strength. We'll actually do double and single leg because they're not the same.

So that's looking at dynamic strength and then reactive strength. We do a double and single leg hop test. So so yeah, th that kind of crosses the boredom. So heel raise endurance test, seated isometric calf calf raise, CMJ, hop test are sort of the four that I use consistently.

Gabe Derman (30:49)
Curious, like do you start with looking at structure first? Like, do you start with UTC first? Typically.

Trent (30:57)
Yep, yep, yep. So order of operations, you know, the least fatiguing

Gabe Derman (31:00)
Yeah.

Trent (31:00)
test. we actually finished with the heel raise endurance test, even though I started with that first.

Gabe Derman (31:04)
Right. Yeah.

Trent (31:05)
we'll we'll do the CMJ, we'll do the hop, we'll do the max iso, then we'll do heel raise endurance after we do the the the structure mechanical property, you know, conversation part of it.

Gabe Derman (31:17)
Do you feel at this point, after looking, even just using UTC and taking a look at things, you have a pretty good guess at what you're gonna be seeing in some of these other tests? Or you really need all those other tests, like have a really obviously you need the other tests to have a really good understanding. They're important. You wouldn't do them if they weren't important. But based off UTC, like is that fairly predictive now at this point for you in terms of what you might be seeing or what you can expect for some these tests?

Trent (31:41)
Yeah, you know, not necessarily. and the reason I say that is again, in in basketball athletes, many of them have structural change already, particularly at the patellar tendon.

Gabe Derman (31:52)
Mm-hmm.

Trent (31:54)
and it can get a bit messy, right, when you try to correlate structure with with with pain and function. Now there is absolutely a correlation with structure with all three of don't get me wrong. But

I would say I I well I have a hypothesis seeing somebody and they can't do a hop test without a two out of ten pain or they just can't keep their heel off the ground doing a a hop test when I'm just trying to identify if they have symptoms before we even do any force plate testing. I'm gonna gather that the amount of time that they spend on the force plate will probably be, you know, three, four, five hundred milliseconds, just because they don't have that stiffness, muscle tendon or tendon stiffness to get off the plate really quick.

so I I think they all matter depending upon the sport, right? Like working backwards from the demands of the game. You know, if I've got somebody that just wants to get off the couch, go in the fridge and and grab a drink and walk back without pain, okay. Well, I know that they just need to tolerate that. And so do I need to have them do a single leg CMJ or a single leg hop test? Maybe not. but I think all of those, because they have distinct or they assess different strength qualities, I do think they're important to design a targeted intervention based on what the athlete needs.

because we can identify again the the rate limiter and what they need to do to complete their task.

Gabe Derman (33:07)
So, you know, I'm just thinking through this now. I'm a basketball athlete, 25, coming through your facility, bilateral, you know, Achilles tendinopathy, like, you know, I I play through it, it's painful. I'm trying to eliminate this essentially.

Among all the input that you're looking for, the things that you listed, heel raise endurance, strength, that's your strength nervous test, max seated ISO, your single leg CMJ, your hop test, your UTC, is there anything else? Maybe reviewing personal factors too, asking questions. Is there anything else? You mentioned blood marker tests too. Anything else that's important for you to understand or collect that we did not hit on?

Trent (33:46)
Other than the subjective, like just again, listening, listening to the athlete, trying to to to to gather patterns because with tendons there often is a pattern of a drastic spike or demand. you know, ev again, just just walking is a lot of body weight on the tendon. And so a small increase in activity can sometimes, you know, light that dry forest on fire, if you will. So again, listening and then describing their symptoms, but then adding

adding to our understanding of where the client or athlete is currently at via all the other objective tests that we talked about.

Gabe Derman (34:20)
Awesome. Now we've gained understanding. We've gathered all this input. I think naturally the next question becomes, Cool. We have all this information, Trent. Now what? What am I doing? Can you expand kinda on your operating model like that helps -- your maybe your decision tree then? Like how do you then start attacking the issue or the problem?

Trent (34:46)
Yeah, great question.

Big picture wise, and this is common in like a a rehab scenario where the start framework, strategic assessment of risk and risk tolerance, Ian Shire, basically says what can the tissue handle? What does the sport demand? And what are the contextual modifiers? And that's how you make your return to play decision. And so in this scenario, I would say all of the objective data that we just gathered provides us insight into what the tissue can handle. From there, that's the capacity.

From there we say, what is the sport demand? Okay, that's the other side of this capacity versus demand framework. You play basketball, you so you're going to have high magnitude of loading, high rate of loading, likely high frequency and high duration. Lucky you. and so it's

Gabe Derman (35:34)
Ha.

Trent (35:36)
we take those two things and then it's is it a preseason game or is it game seven of the NBA finals? Right? Like that contextual modifier gives us an insight into how much risk we're willing to tolerate.

into allowing this athlete to return to play or not. And so starting with just the the bigger picture framework, again, we're trying to measure capacity, we're trying to compare it to demand and taking any consideration of the contextual modifiers. So understand where they're at, know where they need to go, and then make a best guess and try to move closer to where they need to go via these feedback loops. Right. Like it's not a perfect crystal ball. we we have to establish or we have to enter the stimulus in loading somewhere, intervention somewhere.

But then we have this feedback loop that we're continuing to gather information on their on their response to train them. So so that that again, big picture, Gabe, that's where we're at. But I I I also want to say too often pain is the primary variable that is relied upon for making some of these decisions. And so I I I do think it's important that you can get somebody out of pain a variety of ways, but that doesn't mean that their function or their structure have improved.

And so especially in tendons, structurally tendons take a long time to change. And they do change, but they take a long time. And so we're we're seeing this lag of these some of these qualities, but yet we're making decision on just the quality that's the easiest that we just talked about, saying greater levels of stress, et cetera, can cause this quality to go up or down.

I think that's a problem. And so again, I I don't test just to test. I do think that testing should be used obviously to

guide decision making. but just again providing an insider of to where where that athlete is at.

Gabe Derman (37:19)
Yeah, just to recap that bigger framework, I really like that. Is what was the capacity of the tissue? What is the capacity of tissue? What is the sport demand or the performance demand? And then what contextual modifiers we have? It's a really simple, nice breakdown that you provided. So my question to you then is if pain is too often relied upon, how do you balance pain and symptoms with like chasing adaptations that you know, like in the long haul would be better for this individual?

Trent (37:48)
It's a challenge. And it's funny, I have a had a a client last week and sh her email to me, she's not local, but she her email said that, you know, I I realized that I was pushing through too much pain because I read that it's okay to have a little bit of pain when you're doing training for attendant. And she took that to another degree, and and didn't end up with as good of outcome as we had hoped for. So pain can be messy and

But it's important to church get an understanding of of how it progresses, how you know how it presents, that sort of thing. And so I'll bring it back to this. The the number one rule in medicine is making sure the diagnosis is correct. Where with the Achilles tendon, with the you know, patellar tendon, there are other factors or other air other other potential tissues that could cause problems. And yet we're just saying, nope, just pain is okay, it's a tendon. Pain is okay, keep pushing, keep pushing.

all of a sudden we've got a swollen knee and we get, you know, further imaging, whatever it is, and oop, it's not a tendon. And so keeping that at the forefront of making sure that the diagnosis is actually correct. but then going back to the the value and assessing and monitoring some of these other domains where I go to function and structure, where I'm looking at pain, I'm looking at function, I'm looking at structure. Pain we can see changes. That's great. Is the function and is the structure also changing?

And if they are or they're not, that also informs our decision making because they develop or they change at different time periods.

So yeah, I I d I don't even know where I was going with that, Gabe, but as you can tell, man, like the pain stuff is just so complex and I think we we just we need to make sure that we agree on we can't just use that subjective experiences. That that subjective experience is our only our our our only tool to make some of these decisions.

Gabe Derman (39:34)
Well, one hand, like on social media, right, which like the average like Gen Pop person and even athletes like around social media, you have like David Goggins running like ultra marathons being like, You can push through anything and then you have medical practitioners being like, you know, once you experience pain, that should be your limiter, you shouldn't do anything. So then you have the consumers in the middle, like, which one do I listen to?

Trent (39:55)
It is tough, man. It's and again, I'm five foot seven from the upper peninsula. I grew up pouring concrete with my dad, so like I I don't say that to pat myself on the back, I just say like I I support doing hard things and like but having some pain with stuff. spending some time in the NBA obviously shifts you to more of the conservative side and I admit that off the front end when it comes to pain. but what I do wanna say is that when it comes to tendons, when there is pain present and when you do have mechanical overload.

you enter this vicious cycle oftentimes where mechanical overload leads to these inflammatory mediators, which then lowers the mechanosensitivity. And what that means is that the tendon then responds to less load. Meaning that you could do the, you could do, you know, run two miles and be fine. But if you have a mechanical overload at some point and you have these inflammatory mediators, well, you could go run that same two miles and it would let you up.

And over time, as the sensitivity, the mechanosensitivity of the tendon cells lowers, we just people can't do the same amount of activity as they as they normally can. And so I bring that up to say, I do think that a little bit of discomfort is fine if we know what we're dealing with when it comes to is it a patellar tendon, is it an Achilles tendon overload? Do they have they don't have any other metabolic factors, etcetera?

the 24 hour pain response or the next morning, you know, their morning stiffness is going down, which is a great proxy for for for you know prognostic factor. if all those things are are trending in the right direction, then sure a little bit of discomfort's fine. But on the flip side of that, if we just stick our head in the sands, what we're doing is we're essentially just, you know, continuing to train into pain and continuing to lower that mechanosensitivity threshold that it takes for that to tip that tendon over the edge.

Because we know that unhealthy tendons have different mechanosensitivity or a lower threshold. So again, to answer your question or summarize it, make sure the diagnosis is correct.

Gabe Derman (41:45)
Mm-hmm.

Trent (41:46)
I do believe in the pain monitoring model, having a little bit of pain, three or less out of ten, both during the exercise and the next morning, it's not worse. I think that's fine. That means your body is is is able to handle that demand, particularly with the patellar tendon. I do think that's necessary over time. But just being mindful of all of that.

in in that if you don't respect it, then you can often lead to a significant lowering in that mechanosensitivity of the tendon.

Gabe Derman (42:11)
You mentioned earlier that it takes time for tendons to change. how long does it take?

Trent (42:22)
If you look at the literature on Achilles repair, the structure's still not back to a good spot, obviously. Obviously, with the the the sutures, et cetera, but even the tendon around it can take 12 months over a year. so depending on the injury, if it is a an acute overload collagen disruption, that tendon can heal at a at a faster rate. if it is more of a chronic degenerative tendon, sometimes

It just doesn't resolve. Sometimes you're stuck with a certain amount of structure. And that's where I think this initial, you know, donut and the whole theory came from. having used UTC and and have seen tendons change over time, they absolutely can change. And unfortunately they take upwards of a year for some of them, but we can, especially with the ability to granularly measure the percentage of changes of that type one versus type three, the echo type one, echo type three.

we can quantify and see some of that change over time, which is really cool. And so so yeah, I I tell people off the rip, you know, don't get tendinopathy because it just it takes a long time to to get rid of it. So the the you know the best training for tendinopathy is not getting tendinopathy at

Gabe Derman (43:31)
in your experience now, I know you've you've mentioned that you've talked to a number of like medical practitioners, and sounds like you know you have some great resources at the Tendon Lab, at least that you can tap into to learn a little bit more. as you take really, yes, you're looking granularly, but you also have this holistic approach to everybody that you see. So I'm curious,

Collagen supplementation, is that an area that you've come across a lot and and have leaned into? What's the efficacy look like from your understanding with something like?

Trent (43:59)
I rely on the evidence, people much smarter than I. And if you look at the literature, you'll see mixed reviews where literally within the same month you'll see something come out supporting the use of collagen supplementation and you'll see something come out that disputes collagen supplementation. So where I'm at currently is I don't make it mandatory or recommend it to everyone.

But if somebody's interested in it and they have the disposable income to buy extra collagen supplements, then I'm not going to discourage them away from that. So so yeah, I but I I'm kind of in the middle of it. and maybe that's a cop out if you will, but yeah, not not necessary in in my opinion, but but again, not gonna do any harm.

Gabe Derman (44:41)
So I imagine a number of people that walk into the tendon lab or who find you have been experiencing pain, right? Or have some sort of dysfunction. They say, I'm having pain. I need to do something about it. I need to find someone who can help. They find you. If we think about tendon development, knowing what you know now, and if we think about injury prevention,

What advice do you have for, I guess, the entire performance world? do we need to wait until someone has pain or injury? you just said, the best thing to do is to not have tendinopathy. So in your expert opinion, what would be the best way to not have tendinopathy?

Trent (45:22)
Yeah, look, I I think I'm trying to, you know, succinctly sum it up and if I had to choose something, I would say make sure you have really strong quads to reduce the risk of patellar tetanopathy and make sure you have really strong calves to reduce the risk of Achelles tetanopathy. Don't do too much too soon. and then, you know, track your structure in the meantime. you know, to be able to to to make sure that we're getting out in front of something bef before it happens. So

So yeah, again, because of the vicious loop that occurs when you have tendon pathology, it's really hard to get out of. And that's why you see people have tendon problems for years and years and years. And so I I think we need to react a bit more urgently when somebody first reports symptoms. And again, look, I know athletes balance on the edge of overuse all the time.

But we need to put more emphasis on avoiding tendinopathy and treating these minor symptoms with load modification instead of just ignoring. Because eventually it's going to get to a point where they have such bad patellar teninopathy, they can't decelerate into a jump shot or a three pointer. Their shooting percentage goes down. Instead of focusing on the patellar tendon, they just get more shots up because they're upset that their shooting percentage goes down and just gets worse and worse and worse. And all of a sudden you have a, you know, a tendon that's in a tough space. So again, I I

the more I do this, the the more I learn from again people in this space. you know, having strong calves, strong quads, being strategic about your loading progressions, taking some time off after certain seasons, but also maintaining some level of a callus or a chronic workload. Like to me that's that's how you would prevent tetanopathy.

Gabe Derman (47:00)
In terms of UTC.

Is this something you're doing every time someone walks into the facility, right? If they're working with you, there's let's say they're visiting three, three to five times a week. It are we measuring every single time? Is it once a week? Is it once every few weeks?

Trent (47:18)
Typically just upon the evaluation, if it is a client coming in that again wants a better understanding of what's going on. In the athletic cohort, we do monitor structure every month, every four to six weeks, because the premise being you can quantify the changes of the ecotypes, which is basically a signal at a very at a zoomed-in tissue level.

of the tendon being overloaded if you have some changes in the echo type one or echo type three. And so I typically do it on either end of that spectrum initially and then at a follow-up, you know, if it is just a local client, you know, four weeks later, just to continue to track changes. I do think that

I know that the words we use matter in how we describe something to a client, to an athlete. And and look, I I I'm all in favor of building robustness and resiliency. And I do think the human body is is incredible and can heal and do all these things. And so I'm very mindful of the words that I use to describe what's going on so that somebody doesn't get latched onto their structure because that's very easy to do, especially when you look at the Achilles tendon and the fear over rupture.

Right, especially the athletic cohort. And so there there is an art to it in my opinion, but we we need to be respectful and mindful of the psychology piece behind all of this and understand an athlete coming in, you know, if if they are the athlete that says, I just gotta push through this, or they're the athlete that I can't do that, my tendon will hurt. because that that changes maybe how you describe something to s to to somebody. So so yeah, it kind of a

Tangent, if you will, but that's at least the time scale for UTC.

Gabe Derman (49:03)
Yeah, well, I feel like you being a former athlete yourself, right, and being around locker rooms, travel, going through the ups and downs emotionally, physically of an entire season, you can really appreciate where people are coming from, you know, when they step into your facility. I feel like that has to have a huge impact on an emotional level, where you can appreciate, hey, this is the journey you've been on.

I know where you want to get to go to, but it sounds like that that's a huge piece of it that that sometimes can go underappreciated,

Trent (49:33)
Yeah, I d appreciate it. I'm I'm biased because it's my own story, but I I do think that there is value in being able to relay, particularly with basketball athletes, you know, having played the game and I always joke that part of the return to play criteria was you had to, you know, beat me in one on one or guard

Gabe Derman (49:48)
Yeah.

Trent (49:49)
me, you know, stop the ball full court. so having some fun with it at the same time and and

Gabe Derman (49:53)
Yeah.

Trent (49:54)
yeah, I'm I'm I'm late thirties, I've got some left sided Achilles teninopathy. I still, you know, try to play every every couple of days and

but I'm in that demographic or that cohort, man, that's at risk. So trying to keep it as long as I can.

Gabe Derman (50:07)
Funny, like I I like playing pickleball with my wife or like racket sports or Padell. And if I haven't played in a while and I know I'm about to go back out, like play in a few weeks or something like that, or I'm talking to some friends, hey, let's start to go play. I start just like hopping around as much as I can in the gym. Like I do. Like I'm going side to side, lateral, up and down, like scissors, like I do as much like little bouncing hops as I can because I I can't be that person.

Trent (50:31)
Yes,

yes. I feel free of that too. I'm like, I'm the you know, the one of the the people that focuses on tendons and and I hurt my tendons. So I'm trying to be strategic from a business

sense too with that. No doubt.

Gabe Derman (50:39)
Scoon scooting around the facility, huh?

That wouldn't be a great look. so if you're thinking about, you know, five to ten years in the future, where you think tendon training is going? What gets you really excited about the future of your work?

Trent (50:56)
A better understanding of the biology and the pathways of teninopathy, I think, will be critical. And we had a an orthopedic surgeon speak at our event last April on basically all these pathways that we can intervene, whether it's through a drug, whether it's something else that can you know stop tendinopathy in its tracks, if you will. And so if we look at all of these other conditions, you know, cancer, et cetera, et cetera, which again obviously important to pour dollars into and understand that to a high, high level.

But the progress that those other conditions have made outpace the progress that we've made in the tendinopathy space significantly. And so the one thing I'm excited about is just the the more attention to the biology behind it and understanding these cellular mechanisms and interactions. But the other side of it, I would say, is zooming in to the tissue level even more to get an understanding of what's actually going on at the tendon and not just making

an assumption based on a GPS or an IMU in saying that they have high levels of accelerations or high speed running, so therefore the mechanical load on the Achilles tendon is really high. I think we'll get to a point where we're actually measuring some of that, like in vivo strain measurement. and that's something that's really exciting because we're able to quantify some of the stressors and just help make more sense of maybe why injuries are popping up. see those are two I've got a list of things, man, but I would say those are two.

and again just probably the third one would be you know better understanding of unhealthy tendons would be the third one where a lot of the literature has been in healthy tendons from a high magnitude or intensity of loading being required. In unhealthy tendons as we talked about the mechanosensitivity is a bit lower. And so maybe you don't need to load as heavy initially to get a good response. But we need more research on that. So so yeah the biology, you know the direct measurement of the strain in vivo of the tendon.

And then the you know, the the the the better understanding of unhealthy tendons are the three areas I'm excited about.

Gabe Derman (52:52)
Awesome. Trent, thank you so much, man. I really appreciate your time. I I wanna give you a second just to maybe talk about the tendon lab. Where are you? Where can people find you? Maybe tell us about your facility and

Services you provide.

Trent (53:06)
Sure, I appreciate the opportunity, Gabe. so the the tendon lab, we're located in northern Michigan, Traverse City, Michigan. about 10 minutes from the airport, right downtown, Traverse City. we we specialize in Achilles and patellar tendons. And you know, we also do some research and so we're involved in various research projects. the one thing I'm excited about is this tendon summit that we're hosting every year. We held our first one back in April focusing on the Achilles tendon.

You know, we we capped it at fifty. We had a wait list. half the group that attended were from Pro Sport, which was really, really cool. presenters were world class. So it was really cool. It was almost like a a a fan in a way, picking some of the presenters up from the airport in Traverse City coming from overseas. So we're holding our second annual one this spring in Traverse City. We'll focus on the knee. So patellar tendon, quad tendon, distal hamstrings.

we've got you know, really, really exciting lineup for that. But we plan to keep this, you know, going every single year just to continue to shine more light on the tendon space and and make it applicable to practitioners and clinicians and being able to interact with the people doing the research. So so yeah, the the tendon lab dot com is our our our clite and then Traverse City Tendon Summit is the the other one that I would just want to plug. So

Gabe Derman (54:18)
Yeah, make sure you book your flight to Cherry Airport.

Trent (54:22)
T V C we we fly direct to twenty cities across the US in the summer. it goes down to just two or three in the winter, but

Gabe Derman (54:29)
A lot of different golf polos, i you know, right there and tendon summit giveaways, I suppose now.

Trent (54:36)
And sleeping bear dunes.

I don't know if you've ran that before, but n another level sand dune if you get a chance.

Gabe Derman (54:42)
All right, make sure you look that up. anyone listening in, you know, you got the Tendon Summit, you got the Tendon Lab. how about social media? Where can they connect with you?

Trent (54:51)
my personal pages is Trent Salo at Trent Salo, Instagram, LinkedIn, and then you know, social media, the Tendon Lab and Traverse City Tendon Summit. So we try to make it easy. So the Tendon Lab, Traverse City Tenant Summit, Trent Salo. You can find us on on IG and LinkedIn primarily.

Gabe Derman (55:07)
Love it. Last question for you before we sign off here. If I'm in Traverse City and I need a really solid lunch or I need a good bite, where am I going?

Trent (55:22)
Little Fleet is an outdoor food truck area. Really good vibes. So if the weather's nice, I would check out Little Fleet. I'm not paid by them, but that's where I would go.

Gabe Derman (55:34)
Maybe in the future.

Trent (55:36)
There you go.

Gabe Derman (55:37)
Last thing I had is that Albert Einstein driven a basketball behind you? I didn't see a

Trent (55:41)
It is. I thought it was fitting. I'm a big nerd, man, but I

Gabe Derman (55:43)
Love it.

Trent (55:43)
still love the hoop. yeah, athlete at heart, but just try to be a better scientist too, so

Gabe Derman (55:48)
I love it. I love it. I think at some point in the middle of the conversation, I think that's Albert Einstein back there. You know, awesome. Well, Trent, thank you so much, man. on behalf of Keiser, we you and anybody listening, we truly appreciate your time. It's such a pleasure to be able to to sit down and and learn a little about tendon health today and really excited to just stay in touch and and hear more about the success of the summit and obviously the tendon lab. So again, thank you so much for your time today. Really appreciate it.

Trent (56:12)
Yeah, Gabe, thanks for the opportunity.