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Stretch Shortening Cycle & The Role Of Pre-Tension
462 Plays9 days ago
In this solo episode of The Speed Lab Podcast, Les Spellman breaks down one of the most misunderstood aspects of sprinting: the stretch shortening cycle (SSC) and the critical role of pre-tension. Drawing from research, coaching experience, and case studies, Les explains why faster sprinters actually produce higher braking forces, how tendons act as both shocks and springs, and why athlete development often overlooks eccentric qualities.
Episode Timestamps
- 00:00 – Intro & why this topic matters
- 01:15 – Braking forces & the stretch shortening cycle explained
- 05:00 – Early coaching mistakes & concentric-only bias
- 08:00 – Why concentric strength doesn’t separate elite sprinters
- 10:15 – Hypothesis: performance = pretension + braking + transition + propulsion
- 11:00 – Tendons as shock absorbers & springs
- 13:30 – Force plates as a window into SSC
- 17:00 – Case study: Jacob Robinson’s eccentric RFD breakthrough
- 21:00 – Case study: River Cracraft tendon remodeling
- 23:30 – Case study: Brandon Jetter improving pretension & ground contact
- 28:45 – Pretension mechanics & dribble drills
- 31:00 – Practical takeaways from force plate metrics
- 35:15 – Training interventions: yielding/overcoming isometrics, reflexive eccentrics, plyos
- 38:45 – Programming ideas (slow, high, and fast force days)
- 42:00 – Redefining “stiffness” & SSC strategy
- 43:20 – Wrap-up, resources, and closing thoughts
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Transcript
Episode Introduction
00:00:05
Speaker
What's going on guys? We're back. It's episode three. Sorry to get the hang of this a little bit. It's been a while, but I'm starting to enjoy it. um I'm going to be doing this podcast solo today.
00:00:18
Speaker
So no Danny, no guest.
Main Topic Introduction: Braking Forces in Sprinting
00:00:20
Speaker
This is a subject I've really just been nerding out on and just studying and and looking into over the past couple over the past couple of months, really, since I was doing the courses that I've been doing this summer.
00:00:32
Speaker
And, um you know, it's something I think our industry needs. I think it's something our industry neglects. And I want to start the conversation. So I'm going to go out and try it out. And, so you know, I might be wrong about a couple of things here and there, but ultimately I think it's important to at least try to
Historical and New Insights in Sprint Training
00:00:49
Speaker
tackle this subject. So going to be talking about breaking forces, the stretch shortening cycle, and the role of pretension in sprinting.
00:00:57
Speaker
It's not something I've i've talked about on air. It's not something I've wrote a course about or anything like that. So it's relatively new. um But this episode unpacks one of the most misunderstood aspects of sprinting and athlete development, which is breaking forces and the stretch shortening cycle, SSC.
00:01:15
Speaker
um For decades, and including the time that I was in college and training in high school, it's it's really been focused on concentric-based strength training. And it's been treated as like the gold standard for speed and performance.
00:01:28
Speaker
There was even a book that came out about how you should eliminate all eccentric training and and and only focus on, you know, concentric only, you know high force, you know, per body weight type thing. Like, that stuff is has been out there for a
The Role of Tendons and Braking Forces
00:01:45
Speaker
while. So,
00:01:46
Speaker
The research that I've seen from Ken Clark, J.B. Moran, Stu McMillan talks about this, Matt Jordan talks about this, and they're all seeing the same things, that elite sprinting is really less about how much you can push and more about how well you can absorb, store, and recycle force.
00:02:05
Speaker
So i'm gonna I'm gonna talk through this. um I might stumble a little bit, but bear with me, guys, because I think this is really, really, really important. We're going to really look at, number one, why faster runners actually produce larger braking forces, which is counterintuitive.
00:02:19
Speaker
But what we've seen is that these faster runners are actually producing higher braking forces. So it's not about minimizing force. It has to be something else. We'll also talk about the importance of pretension to really just remove the tendon slack.
00:02:34
Speaker
and to set up elastic returns. So it's essentially preparing for that ground contact and being in a pre-stretched position so that when you do make that initial contact, that tendon can operate the way it's supposed to without slack.
Force Plates and Athletic Force Management
00:02:48
Speaker
um We'll also talk about how tendons act as shocks and springs, to two different things. And basically they protect the muscle fascicles while recycling energy. So the muscle has an isometric effect where the muscles are contracting.
00:03:07
Speaker
Alex and Tara talks a lot about this where the soleus and the gastroc, for example, on the lower limb are in a semi-like isometric contraction while the soleus is stretched and stores elastic energy for the propulsion phase.
00:03:23
Speaker
We'll also talk about why force plates can give us some insights. It's, you know, obviously it's it's limited because we don't have force plates on every track. rio Nagahara In Japan, it's done a ton of work with force plates on a 60 meter track.
00:03:38
Speaker
We don't all have that, but force plates can give us some global insights into how the athlete is physically managing forces, how they manage the braking phase and the deceleration part of the the jump and then transitioning into the propulsive side. So we'll talk about that a little bit.
00:03:54
Speaker
um We'll talk about how different jumps lead to different outcomes. We'll talk about the difference between a squat jump, a kind movement jump, kind movement jump with arms and a depth drop. We're all several different things, right?
00:04:07
Speaker
They're not all the same thing. And they all illustrate the stretch shortening cycle and and with different speeds and different ah magnitudes going into it. And then lastly, we'll talk a little bit about some practical interventions. Like obviously the solo pod is hard to kind of just talk through these things without visually showing you.
00:04:24
Speaker
So I'm going to talk to him on this. we'll We'll see how far we get. and then I'm going to follow up with an actual visual and then potentially some more written stuff.
Evolving Training Approaches
00:04:33
Speaker
So let's let's dive in.
00:04:35
Speaker
I've already taken up four minutes of time. Hopefully you haven't skipped. Let's keep going.
00:04:41
Speaker
All right, so the next piece here. So early on in my coaching career, I was reading Barry Ross. I was reading all about concentric level strength training, physical development for sprinters. So I had a track team at the time, and i basically controlled their weight room, their field, everything, their sprinting.
00:05:03
Speaker
And I only let them do concentrical and lifting. Well, you know at that level, it worked because they weren't very strong. And getting any level of strength allows for that strength to be used faster or whatever you're trying to do with that. You have more available strength to then carry out the tasks that you want to carry out.
00:05:20
Speaker
So at the time, it worked. And I was biased into that thinking, hey, combine, I should do the same thing. So I had my first combine group not too long after. And it was the same flow, like it was concentric only lifting.
00:05:33
Speaker
It was a trap bar deadlift drop at the top, you know, wanted to remove all soreness. And, you know, the truth is, is that we ended up getting higher jump heights. We ended up getting somewhat faster speeds. Obviously, like combine training is not hard to get guys faster because you're actually removing the thing that makes them slower, which is tons of football practice and volume and other competing demands.
Case Studies: Training Strategy Impact
00:05:56
Speaker
If you just sprint and lifted, like pretty much everyone's going to get faster. But that's besides the point. um Guys did get faster. Guys did jump higher. Guys did jump further.
00:06:07
Speaker
but I had a lot of guys break. And I was trying to figure this out throughout the years. I'm like, maybe we need to switch our exercises. Maybe we need to have a little bit more um unilateral work in there. So I tried different things.
00:06:20
Speaker
And I couldn't really find a solution. But, you know, honestly, I think back to my career as an athlete and how I trained. And the way that I trained was very concentric dominant, very power-based.
00:06:32
Speaker
Like, I only wanted to do um power cleans, but, you know, i I caught it really high. that didn't I didn't drop down at all. I only wanted to do box squats because I wanted to eliminate the eccentric phase and as much as possible and just focus on the concentric side of things.
00:06:50
Speaker
um You know, I was just very concentric dominant. like and i And I was an average athlete. I wasn't wasn't anything special, but I was an okay athlete. I had tons of issues.
00:07:01
Speaker
I had tons of pain in my body. Always had this chronic tightness. I couldn't really figure it out. So... I ran into Stu McMillan probably in 2017, 2018 during ACP.
00:07:12
Speaker
And I watched him do all these like crazy movements. At the time, I didn't understand it, but it was kind of the beginning of the reflexive eccentrics that he does, which which I'll get into in a second.
00:07:24
Speaker
um But one of the things that I realized during this process, and i think Stu realized with Matt Jordan as well, is that there wasn't a high correlation between the concentric-based lifting that I was doing and the athletes were doing and the outcome, which was being the fastest or best athlete on the team.
00:07:41
Speaker
there wasn't a high correlation between those things. In fact, it was somewhat of the opposite. It was somewhat of the opposite. um So Stu went on to say concentric strength does not separate elite sprinters.
00:07:52
Speaker
And i agree. I think if I were to line up all the athletes that I've had that were the fastest, they wouldn't rank the highest in the concentric-based strength metrics.
00:08:03
Speaker
In fact, they're probably in the lower end of that. And as you look across sprinting nowadays, like, without drugs involved in the sport.
Debunking Training Misconceptions
00:08:11
Speaker
Like you see a lot more ah body types that are elastic and smaller and guys you wouldn't think were very fast or could produce high forces, but they're producing extremely high forces. The forces haven't changed, right?
00:08:25
Speaker
So it's it's super interesting. Matt Jordan's talked about this extensively, saying the best athletes are the ones that can manage the stiffness and eccentric braking rate force development piece of the of the ground contacts, which we'll get into in a second. So super interesting. Now, Ken Clark has also confidentially told me, and now he you know he said it on our last podcast, so it's out there, but faster runners actually produce larger braking forces.
00:08:53
Speaker
and They ah obviously produce higher vertical forces, which is why they're faster, but they produce higher braking forces as well. And the demand required by the body with higher vertical forces is also a higher braking demand, which we'll get into in a second.
00:09:09
Speaker
So super interesting. So the core question of all this, are we focusing on the wrong things in athlete development? you You look across the board, we have 225 speed labs with universal speed rating. You have tons of high schools we're working with, tons of soccer teams we're working with.
00:09:27
Speaker
I would say the general consensus around strength training is to build size and to build concentric-based qualities. So I would say, honestly, yes, I think we are focusing on the wrong things.
Muscle Tendon Unit and Sprinting Performance
00:09:40
Speaker
The second core question I have is should eccentric qualities tendon health, and braking efficiency be prioritized along with the outputs?
00:09:51
Speaker
So I still believe outputs are good. But should we should we look at these things as well? Obviously the answer is is yes. So my hypothesis for today.
00:10:03
Speaker
Sprinting performance equals how well an athlete can, number one, pretense the muscle tendon unit, and i'll I'll define what a muscle tendon unit is in a second, before ground contact.
00:10:17
Speaker
Number two, how much braking force they can apply in the initial half of the ground contact phase. That's the second most important thing. Third is how they transition from the braking through the amortization phase. So I think about the transition from braking to propulsive. So how well they manage that phase.
00:10:38
Speaker
And then lastly, how they recycle that elastic energy into propulsion. So I think sprinting has a is a major component ah redefin redefinition here and in terms of what makes athletes good.
00:10:53
Speaker
um and Before I go on any further, I want to talk about the tendon and just like maybe the muscle tendon unit. So you have a muscle in the middle, you have two bones at the end, you have tendons that can connect the the bone to the muscle.
00:11:06
Speaker
So the tendon plays an interesting role. So number one, the tendon acts as a shock absorber. So when the foot strikes the ground initially and ground reaction force spikes, the muscle fibers alone could not absorb that load.
00:11:22
Speaker
Essentially they would lengthen rapidly and probably be prone to straining or tearing, which happens. um Instead the tendon actually stretches first and it takes on the majority of the shock of the initial impact.
00:11:33
Speaker
ah By stretching, the tendon reduces how much the muscle fascicles have to lengthen so that muscles can actually be near isometric, protecting the muscle from excessive strain. ah This is why compliant tendons like the Achilles are essential, but you need some level of compliance and some level of stiffness because that tendon has to be able to stretch.
00:11:55
Speaker
It also has to have a level of stiffness that to resist the the load that's coming down on top of the tendon. um So it's gotta be both, both somewhat compliant, somewhat stiff.
00:12:07
Speaker
Okay, it can't be too stiff, it can't be too compliant.
Analyzing Tendon Efficiency in Athletes
00:12:10
Speaker
Okay, the second thing is a tendon will act as a spring. As the tendon elongates, it stores elastic energy, it's like stretching a rubber band.
00:12:20
Speaker
Okay, during the amortization phase, the energy is held for a brief second. So the brief isometric of the tendon. And then when propulsion begins, the tendon actually recoils, returning much of that stored energy to help push the body forward.
00:12:33
Speaker
Okay, this elastic recoil improves efficiency. There's less metabolic cost, faster movement, and higher outputs. Okay, a stiffer tendon recoils faster.
00:12:45
Speaker
So it's more explosive of a propulsion. A more compliant tendon absorbs more but may reduce the last return if it's too loose. Okay, and we'll talk a little bit about the injuries that are associated with too stiff or too compliant, right? it's You got to be somewhere in the middle.
00:13:00
Speaker
Okay, so it's got to be both compliant enough to absorb the shock So reducing the muscle strain, but stiff enough to recoil quickly. All right, so too stiff means basically you're poor your poor shock absorber, you have poor shocks.
00:13:15
Speaker
and you have a higher calf and Achilles risk of strain. ah Too compliant, the energy will essentially dissipate and the muscle fascicles will basically fatigue faster and be inefficient, um which which could lead to strains and other things like that. So there's a sweet spot within that. And we'll talk a little bit about the training to develop both of those later on in this podcast.
00:13:41
Speaker
um Now, one thing that I should probably talk about before diving deeper into the sprinting side is that over the past couple of years, force plates have become a really good tool in terms of evaluating the stretch shortening cycle for an athlete.
00:13:59
Speaker
So if you were to just think about it simply, the stretch shortening cycle, you have an eccentric phase, you have an amortization phase, so somewhat of a switchover, and then you have a concentric phase.
00:14:11
Speaker
um And if you think about a jump, the jump utilizes eccentric forces driving down um as the muscles stretch and then you transfer that over into a propulsion.
00:14:23
Speaker
um Now if you were to think about the different types of jumps you could do, you could do a squat jump, restart at the bottom, where you basically eliminate that eccentric phase and it's primarily concentric.
00:14:34
Speaker
You could do a counter of movement jump, hands on the hips, start at the top, drop down, have an eccentric phase, and then jump regular. You could do the same thing with your arms, which adds a little bit more, ah but i would say little a bit more speed down into that jump.
00:14:49
Speaker
Or you could do a depth jump. Now, those four are pretty interesting because each one that I mentioned is a little bit higher. So the squat jump to CMJ, CMJ is higher. CMJ to with arms, with arms is a little bit higher.
00:15:03
Speaker
with arms to depth drop is a little bit higher and they all utilize the stretch shortening cycle a little bit different.
Efficient vs Inefficient Use of Tendons
00:15:10
Speaker
And then one factor that goes into that is speed. So the speed going into that stretch shortening cycle determines kind of what you're getting out of it.
00:15:19
Speaker
So that depth drop is actually the highest jump potentially, like you could have some issues on some technical stuff. Um, But yeah, that that depth drop actually utilizes stretch shortening cycle the best and allows for more jump height than you would get if you were just to jump on your own, right?
00:15:38
Speaker
um So we could also utilize the force plate to understand a little bit about how the tendon works, right? So an athlete that has really good breaking rate of force development is probably gonna have a better utilization of their tendons because of how fast they can turn on eccentric force and how quickly they can basically stabilize that to then transfer that over and load the tendon to transfer that over to the propulsive phase.
00:16:06
Speaker
So efficient athletes will technically have a better eccentric phase, which shortens the amortization phase and have a higher elastic return. Whereas inefficient athletes will have a longer breaking phase.
00:16:18
Speaker
They'll have some more time in the breaking phase, essentially. um They'll have a a a worse amortization phase and they'll have less of a spring of effect. So really that you think about from a training perspective, if I'm training an athlete and I know the problem, the problem is a lot of these athletes have an overemphasis of concentric output. So like chasing barbell strength and jump scores, um and they neglect their centric and SSC qualities. They're gonna have a lack of ability to amortize these forces when they hit the ground, when they're sprinting.
00:16:56
Speaker
um Now, basically what we're looking at here is an athlete that's probably had too stiff of a tendons, poor shock absorption, or they're too compliant.
00:17:08
Speaker
So the frascals lengthened excessively, right? So I end up in two different buckets.
Case Studies on Tendon Optimization
00:17:12
Speaker
All right, so moving on. ah Ken Clark's research, elite sprinters don't reduce braking. They prepare for better with pretension and rapid reversal. So this is Ken Clark's ground speed difference where the body's moving at 10 meters per second.
00:17:26
Speaker
The leg that's coming back into the ground is moving about seven meters per second, and then it impacts. When it impacts, these sprinters that have higher speeds, we'll have higher braking. Makes sense.
00:17:37
Speaker
So we had an athlete, Jacob Robinson. He came in, he ran about a 4.65, 4.67 in that range, in a 40. And, you know, it was a corner, 190-ish pounds, six feet tall, coming from BYU. We knew that he was probably going to be undrafted free agent.
00:17:55
Speaker
So, In his case, he had to run fast. Like he had to run four fourers, four threes to be able to be considered to be picked up as a priority free agent and potentially make the team 53-man roster, which I hope he should in a couple weeks here.
00:18:11
Speaker
Now, when we tested him, we went through James Wild's quadrants. So we went through the, you know, basically James says has identified four different strategies of running based on if you're ground and air-based or stride frequency and length-based. So end up in one of four quadrants.
00:18:29
Speaker
So you could be step length and air-based and be a bounder. which is the air strategy um and a step lane strategy. Or you could be a step lane strategy and ground-based strategy, which is a driver.
00:18:42
Speaker
Or it could be a step frequency in ground-based, which is a spinner, or it could be step length in air-based, which is a bouncer. So each of those abilities also has physical attributes that match up with what it takes to be good in those strategies. So Jacob in this case is a spinner.
00:19:01
Speaker
So high stride frequency, but also high ground time. And if you were to test him, let's say we took Alex Natera's test on the hip ISO, he's got an extremely strong hip ISO. So he we know he has strength through his hip extensors.
00:19:15
Speaker
um Now, when we did all the reactive tests, like he's okay, he's moderate. like He wasn't great at the 10-5 RSI. He wasn't great at the drop jump. um He was good enough and he was okay with the ankle ISO and those types of things.
00:19:31
Speaker
But when we looked at his force plate, The one key factor is that while he could produce a decent amount of eccentric force, decent, not great, he could not produce that eccentric force fast.
00:19:44
Speaker
So when we looked at the eccentric deceleration RFD, which is essentially, if you look at the braking phase on VAUD, so it's everything from the end of the unweighting to the top where you you reach your peak forces in
Impact of Eccentric Training Adjustments
00:19:59
Speaker
the eccentric phase.
00:20:01
Speaker
that whole thing is breaking. Now the deceleration phase on Vald is essentially when you start producing force in that breaking phase greater than your body weight. So that deceleration phase is centric deceleration RFD.
00:20:15
Speaker
How fast I can produce eccentric deceleration forces, how fast I can stop and switch and transfer that force from eccentric to concentric, um that was really poor for him.
00:20:28
Speaker
So... Looking back, knowing that, we we looked at the training program, like he's he's decently strong, but we really need to emphasize how fast he can produce essential courses. So you look at drops, you look at catches, you look at oscillations, you look at yielding isometrics, overcoming isometrics.
00:20:46
Speaker
We threw everything at it, right? Jacob went from 4.65 to a 4.39 and also jumped 38 inches in the vertical jump.
00:20:57
Speaker
So he had an insane change. And and really what what helped him on the sprinting side is that we were able to manage the braking, which actually shortened his ground contact time and actually made him less of a ground-based runner.
00:21:11
Speaker
Now he wasn't like, he didn't switch over to air-based running at all. But it reduced his strategy down and also reduced some of his hip pain because the longer you're the ground, the more torque you're experiencing and probably the more rotation you're experiencing in extension. it And Danny Foley could probably speak to that better than I can because I don't fully understand it um But his strategy changed and shifted into a ah more air-based strategy without going into air-based.
Case Study: River Craycraft's Return Strategy
00:21:41
Speaker
We got him more efficiency on the ground contact, so shorten his ground contact.
00:21:47
Speaker
um Another guy we looked at is River Craycraft, who we did the return to play with. We've talked about it like five times because it's exciting. He's on the commanders now. It's really fun to watch.
00:21:57
Speaker
um But River, in his case, he had very, very, very stiff tendons, but not very compliant. So what happened was is when he's running and he has this and incredible stiffness at the tendon from years of heavy concentric strength training and and all of that, the muscle fascicles were put at a stretch when they, really that was a job that attended, right?
00:22:23
Speaker
So he ended up with these, he ended up with bilateral calf strains and and issues with both. And when we were looking at his force plate data, we saw that he was actually extremely good at the centric deceleration, RFD side of things.
00:22:38
Speaker
So we knew that, okay, we need to understand that the tendon needs to be a little bit more compliant. And in the return to play process, we knew that we had to return him back to that quality that made him so good.
00:22:51
Speaker
So knowing the pre-number, knowing where he was at when he came back from the injury, we just worked towards it with reflexive eccentrics and drops and um all the work that Danny was doing to get the tendon a little bit more compliant, but also putting loading the tendon, putting more force to the tendon, not backing off of it. So putting more force and and really trying to remodel it as much as we could.
00:23:14
Speaker
And then returning him back to the eccentric braking deceleration qualities that he had. And the dude ended up running 22 miles per hour, which is one of his highest, and also having one of the highest vertical jumps that we've we've seen.
00:23:27
Speaker
So it's incredible. um The third case that I saw in this was Brandon Jetter, Bob Sutter. Now Brandon's exhausted pretty much all his available concentric abilities. Like the dude is insane. Like he was squatting 535 at 0.75 in a box squat the other day.
00:23:47
Speaker
Right. So eventually were like, dude, you're not, you're not getting much more out of this. He obviously he's a ground-based strategy. He's a spinner. Um, he's got very high frequencies.
00:23:59
Speaker
Doesn't really spend much time in the air, so like the ground is is his friend, but he likes to push.
Case Study: Brandon Jetter and Eccentric Forces
00:24:04
Speaker
What we noticed on Brandon, and there's a couple other issues in here that that Danny's talked to a little bit, is that he didn't manage the ground phase, specifically the first half of ground contact.
00:24:15
Speaker
And what we know about ground contacts, especially at max velocity, is that you have to spike it really hard in the first part of the ground contact to create that big spike in vertical force, to to manage that ground phase in the first half quicker.
00:24:29
Speaker
Now that that big spike also coincides with the big breaking spike as well. um And if you can't manage that breaking spike, then there's going to be leak somewhere. So what Danny identified is that when he hits the ground,
00:24:44
Speaker
He has a poor post-tib reaction of the tendon. um And essentially what happens is post-tib attaches to the navicular, navicular drops. So basically pronates, his foot drops and rotates and the energy is lost. He end ends up spinning longer on the ground on that one side.
00:25:03
Speaker
um And now on the other side, he tries to pick it up. So he's got this really asymmetrical stride pattern that was like incredibly... It looked weird. It just looked weird. I'll show out i'll show a video of it sometime.
00:25:15
Speaker
um So long story short, Danny worked on the post-tip and the navicular and all those things that I barely understand. And I worked on the quality that he was missing the most, which is the ability to apply large and fast amounts of eccentric force.
00:25:33
Speaker
So we did everything from drops, ah from 36-inch boxes, to rear-foot elevated catches with weight, to yielding isometrics, like everything. and We threw everything at it.
00:25:49
Speaker
And within a short period of time, like three to four weeks, This dude went through the roof like he was he was running I'll just give like a quick example like he was running about 102 103 on average in his 510 his 20 10.
00:26:02
Speaker
on average in his five ten his twenty plus ten after a three week block of doing this reflexive eccentrics and isometrics and Danny's work and all that, and he hit 0.94 yesterday. And not only that, like this is the piece that's probably the most the most surprising to me is that in his force plate jump, his force plate jump was like around 23 inches impulse momentum.
00:26:27
Speaker
um He touched 24 once, he touched 25 once. So like most of his jumps were in the 23 impulse momentum, 23 inches. Now yesterday he jumped 26.1 inches and he produced the highest eccentric deceleration RFD that he's produced ever.
00:26:45
Speaker
So he was able to move through that eccentric phase and rapidly reverse it, like very fast. Now to go like into a deeper dive into this and to Vol's metrics, on the propulsive concentric side, there's two phases to it. There's a P1 and the P2. So P1 is the first half of the propulsive phase.
00:27:04
Speaker
P2 is the second half. Well, Brandon was like 100th percentile in P2. It's like the push-off. He got really good at compensating, like most athletes do, good athletes do.
00:27:15
Speaker
He got really good at compensating and over-pushing in that P2 phase. So he would basically... drop down and then jump and basically sink down without without producing large forces and just try to muscle his way into a high jump.
00:27:32
Speaker
And actually, he got pretty good at doing that strategy. when we added in the deceleration RFD, his... Issa, not only that part got better, but P1 got better too, which is like the initial 50%.
00:27:47
Speaker
So his concentric net impulse at 100 milliseconds and increased like 12%, all right? And P1 increased significantly. So it it was massive, right?
00:27:59
Speaker
Um, the other part about that is Brandon actually improved his pretension.
Pretension's Role in Sprint Efficiency
00:28:04
Speaker
So pretension is incredibly important and i kind of like segue into this a little bit because, because it's on my list of things to talk about, but, um,
00:28:15
Speaker
Here's why pretension's important. So without pretension, essentially what happens is when you touch the ground without pretension, there's slack and the in the tendon. So there's no if there's no pretension, there's slack, and and basically the body has to react to that slack by reducing the height. So basically it draw it' will drop your body will drop.
00:28:39
Speaker
So imagine you have a flat foot contact. and you have to absorb through the muscular effort because the tendon hasn't picked up the slack, right?
00:28:50
Speaker
Now, it's it's not only gonna cause performance decline, but also it's risky. So what pretension does is basically it switches on everything, the muscle tendon unit, before ground contact and puts it at a stretch and basically puts the muscle at the length that it needs to be at. So dorsiflexing, right, is basically going to put the backside the soleus the gastroc and all that is already somewhat firing before. And it's also going to put the tendon at a stretch.
00:29:22
Speaker
So when that foot hits the ground, the gastroc and the soleus are lengthened but isometrically contracting while that tendon can immediately go into what it's supposed to do, which is stretching and storing elastic energy.
00:29:38
Speaker
And if you think about this in the in the case that we talked about with Brandon, Like he didn't manage that first part of the ground contact well. And there's there's reasons that are health related, like the post-tip stuff and navicular and all that. But um we knew that if we could work on teaching him through progressively adding speed into the drops and plyometrics and sprinting with a little bit of a focus on it, that we could improve the pretension strategy, that would help. So long story short,
00:30:11
Speaker
we were able to influence that. the The way we did it was really dribbles, to be honest. Like we did tons of dribbles and we did assisted dribbles. So high speed dribbles where the 1080 was pulling him into the machine and pulling him like 19, 20 miles per hour. So not like, it's not over speed technically.
00:30:29
Speaker
But what we're working on is just repetitively working in that pretension strategy of his foot slamming into the ground with a dorsiflexed ankle, right? So initially getting into that.
00:30:40
Speaker
um So with pretension, you have shorter contacts, you'll have better propulsion, you'll have better efficient recycling of elastic energy. Without pretension, they call it electromechanical delay. So it's like a soft landing, right? wasted and energy, right? which Which is kind of what he had.
00:30:55
Speaker
um It's kind of like pulling back a bow and arrow before releasing it, right? Um, so yeah, I, I think there's a, there's a lot here and I know I've gone on a few tangents here.
00:31:07
Speaker
Um, but just to summarize on the, on the force plate side of things, there's a couple of things that we're looking at. So one, we'll look at impulse, both braking and propulsion, because that's going to be your force and time categories.
00:31:22
Speaker
Um, you, you want high force, little time, um, For eccentric rate of force development, eccentric deceleration rate of force development, it's how quickly that force is absorbed.
00:31:34
Speaker
Concentric impulse I mentioned at 100 milliseconds is... essentially the power generated after braking so the right side of the curve um and in the concentric and then you have phase ratios p1 versus p2 so it's a strategy um really of like are you are early ah are are you generating that power early or late in that drought and some people can produce it late if they're very strong um So another thing I wanna talk through on this and and just kind of to close this this whole thing up is that sprinting has to do with preparation for the ground and what happens on the ground.
00:32:16
Speaker
So the preparation for the ground has a lot to do with how much can you wind up, really get a big split between your thighs, how fast can you reverse it? So the switching piece, how fast can reverse it from peak flexion extension?
00:32:32
Speaker
back into the ground with a stiff ankle. And if you do that really well, you have the opportunity to create a big spike in your ground reaction force in the first half of contact, which allows you to manage the back half lot and the front half a lot faster, but the back half more efficiently.
Comprehensive Force Analysis in Sprinting
00:32:51
Speaker
Because if you can get the back half done more efficiently, you could start basically, you'll you'll you'll see um if you were to have EMG on athletes, you'll see the hip flexors start to fire before toe-off slightly, which allows the recovery to be a little bit faster to manage that rip phase.
00:33:08
Speaker
which which could be honestly god-awful. If you don't have any pre-activation of the hip flexors before toe-off, you'll see the pelvis tilt backwards and the legs swing out behind you and put you in a bad position for the hamstrings. like This is where Jordan Mendiguchi has done a lot of his research and Johan Latsy has done a lot of the research on that that rip phase. So how how the pelvis tilt can influence um the strain on the hamstring during that phase.
00:33:39
Speaker
So if you think about it, it's like a cycle. So you have the attack phase, I have a high front side, and I attack down towards the ground with a stiff ankle. So if I do that really, really, really fast, I increase the forces that I get to the ground.
00:33:55
Speaker
then you have the push phase. So if I increase the force to the ground, ground reaction force, I can move through that phase faster. I can also um overcome the breaking forces quickly.
00:34:06
Speaker
And that allows me to push through where I can rip and then punch. So it all kind of works it all kind of works together. And what we fail to really focus on is that the most important piece of sprinting is the forces that are involved on the ground.
00:34:24
Speaker
And everything else is kind of just prepping for those forces and and helping to attenuate those forces. um And I think what we've misconstrued in the industry is thinking, okay, well, if it's about forces, let's just get stronger. Let's get stronger and stronger and stronger and stronger and stronger.
00:34:41
Speaker
And... failing to realize it's not only just how fast you can produce that strength, but ah those forces, it's also about how well you can manage a mor themorization the amortization, the stretch shortening cycle that's involved in sprinting.
00:34:55
Speaker
And I think it's something we should start to pay attention to.
Enhancing Stretch Shortening Cycle
00:34:58
Speaker
um So just to recap and and kind of give some practical advice on this. I think as a solution between the athlete, the coach, the therapist, we need to promote a little bit different training interventions to improve the stretch shortening cycle and pretension. So one, um I'm going to start at kind of like one side of the equation. So if yielding isometrics, so this will help with tendon tolerance under braking.
00:35:26
Speaker
um So basically grab a weight, hold it in an isometric position, heavy enough, it'll help that ah tendon adapt. ah You have overcoming isometrics, so it's really just the explosive stiffness and sprint-specific joint angles.
00:35:41
Speaker
I like overcoming isometrics, especially at the ankle, because it it puts the muscle, the gastroc and the soleus, under isometric load. And it's teaching that to contract with enough force that would be equivalent to what you experience probably in sprinting, like three to four times your body weight.
00:36:00
Speaker
And if you can do get better at that, then it allows the tendon to do it its job, which is stretch under load. um We have reflexive eccentrics. This is Stu Matt Jordan's work here. So rapid reversals to simulate braking and propulsion. So you're you're driving it with speed into the braking phase and you're quickly trying to reverse it.
00:36:20
Speaker
It's not necessarily heavy loads, um but if you try this, you could do it in season, a lot of it, because it doesn't induce a large amount of DOMS. Like you you don't see a lot of DOMS in this.
00:36:32
Speaker
um and And the benefit of that is that you could do it with a little bit more frequency and then you're really working on the breaking rate of force development, but you're not inducing hypertrophy. It's not a big strength exposure, all those things.
00:36:47
Speaker
Um, You also have oscillatory isometrics. So you're you're moving through end ranges with this and you're playing with how to how to basically reverse that, the break into propulsion.
00:37:02
Speaker
um And then obviously you got plyos. So plyos help with the pre-activation. It helps with the stiffness side of things and it teaches them to arrive at the ground prepared.
00:37:13
Speaker
It teaches them how to prepare for the ground attenuate those forces and move into propulsion. Um, a couple more on this. Like I took some notes before this because I've been reading up on some people that are a lot smarter than me on this.
00:37:29
Speaker
Um, and obviously like I looked at Sportsmith and there's like a ton of information from the eccentric side on, on Sportsmith. So I'm just going to read some of this to Um, All right, so we have on the eccentric side, we have super maximal loads.
00:37:45
Speaker
So meaning loads that are heavier than the athlete can can do on the on their own. So heavier than the one rep max. So this is going to really help their strength and their hypertrophy and their power.
00:37:57
Speaker
And it's really going to build that engine eccentric forces that the athlete can then use to move faster. um From there, we have sub max extenuated eccentric loading.
00:38:09
Speaker
This is going to kind of load to everything. So this is um like weight releasers and things like that. so maybe it's like 80 to 90% of the concentric side, but it could be 120% on the eccentric side.
00:38:23
Speaker
So strength, hypertrophy, power, rate of force development are all impacted. um From there, you have flywheel loading. So it's not, flywheels won't necessarily increase the strength side of things, but hypertrophy and rate of force development definitely get impacted on this.
00:38:38
Speaker
um Then you have tempo training, and this is kind of what
Advanced Eccentric Training Methods
00:38:42
Speaker
I think most people think about eccentrics is like, a slow countdown. Now, the research that I've read, and I could be wrong, is that you don't need to really go more than two to three seconds on the tempo side of things. And if you're going five or six, there's a diminishing return.
00:38:57
Speaker
um So this is going to help with hypertrophy. It's really good for athletes that are learning technique and things like that. um Then we have negatives where we're really just focused. Like, you can lower a weight that's way higher than you can push it up, concentrically push it up.
00:39:15
Speaker
So it's, it's loading that strength side of things, like where I'm just punishing that negative side of things. Um, then we have accelerated eccentric loading. So this is really going to focus on the power and the rate of force development side of things.
00:39:30
Speaker
Um, like I would think of this as like some band tension driving down. Um, It's really gonna attack. like Obviously, I'll get a little bit of a strength exposure, but very little hypertrophy, mostly power to force development.
00:39:47
Speaker
Okay, then I have accelerated eccentrics. So this is, again, power, rate of force development, accelerated eccentrics. um This is gonna help increase my ability to reverse, to reverse. So coming out of the hole, essentially.
00:40:03
Speaker
um i' have over-speed eccentrics. Like imagine if I might pull myself down with some bands and then rip myself out and do a concentric jump. um Again, power rate of force development.
00:40:14
Speaker
Okay, then I have my shock method, power rate of force development as well. So, plyometrics, shock method. And then I have the two-to-one method. So, if I were to pull with both arms on the way back um the on the eccentric side, I'm sorry, on the and concentric side, and then lower one arm on the eccentric, that's going to work your strength and hypertrophy. Now, I just pulled these straight from Sportsmith.
00:40:38
Speaker
um And the way that I really think of this is, If I were to to program and plan, I would probably use something close to hunt Hunter Eisenhower's force system.
00:40:50
Speaker
So I would have a slow force day. So it might include some tempo or or super maximal loads that are focused on strength hypertrophy. um Then I would have a high force day where I'd work on more the shock method. So dropping into from from high speeds into a a really big high, you know, high force, it might be rear foot elevated drops, overcoming isos.
00:41:15
Speaker
Oh, I'm sorry. And the slow force day, I would do yielding isometrics. On the high force day, I would do more overcoming isometrics. um And then could have a fast force day, which would be more reactive based stuff and maybe some overspeed eccentrics and things like that. So, you know, I, I'm not going to speak for Hunter on this. Like,
00:41:34
Speaker
We've probably only spoken through social media, but I would recommend just checking out his four system, his podcast with the needle. If you want to, if you want to learn a little bit more about that, but it's been a huge help for me to kind of conceptualize and put all this stuff together.
Conclusion and Call for Engagement
00:41:49
Speaker
Um, but yeah, that's pretty much all I got on this subject, man. This has been the source of the past couple of weeks, staying up late and trying to understand this piece.
00:42:01
Speaker
Um, and try to understand ah the idea of stiffness, right? Because when we think of stiffness, we think of just global stiffness. Like you hit the ground, it's stiff. Well, the stiffness that we're looking for is actually the muscle during the eccentric the amortization phase is contracting hard enough to to really stay isometric while the tendon does have some compliance to it and and does is it is able to stretch. It's not completely stiff, doesn't move.
00:42:32
Speaker
all together and that creates the stretch reflex that then creates the propulsion. So understanding how the muscle tendon unit works with the lengthening um and the shortening, it it's it's a little bit different than i once understood. So I wanted to make sure that was clear.
00:42:50
Speaker
um Ken Vick has also talked a lot about this with Shocks and Springs. He's been posting some really good stuff on on Twitter. I'm gonna try to get him on the podcast pretty soon. um Matt Jordan is another one.
00:43:03
Speaker
I suggest looking at his courses online. They've been a huge help for me in understanding. like I bought it pretty much every course. like it's It's helped me understand just the the force plate side of things and just how the short shortening cycle is utilized in the force plate.
00:43:19
Speaker
And we can see things in there that we wouldn't be able to see with just concentric-only outputs. um Yeah, that's all I got, guys. Make sure, make sure, make sure you guys not only just watch this episode, but you subscribe to the podcast and then tweet about it.
00:43:39
Speaker
Get more people. Send it to two or three people. That's how it grows. um i'm I'm starting to dedicate almost all my time to the podcast world and digital world. So this is not how I feed my three kids. So this is...
00:43:52
Speaker
really important. It means a lot to me if you guys share, comment, start a discussion. Even if you disagree with something, it's cool. i Just don't be disrespectful because like I got to get on your ass. But otherwise, i i love the discussion.
00:44:05
Speaker
i love disagreements and and things that are healthy and educational and help me learn because this is all learning process for me. So appreciate you guys a ton. Let's hop back in. Next week, I got a couple guests that you guys are going to be like, how did you guys get this dude on there?
00:44:23
Speaker
So I'm really excited about this, man. So thank you guys again, and we'll talk soon. Peace.