What's up everybody? I'm Isaiah Rivera. I have a 50.5 inch vertical. This guy right here is John Evans. He's coached me from a 42 to a 50.5.

We're also responsible for coaching four out of the six fifty inch verticals that have been officially recorded. And today we're going to be talking about something called your reactive strength index. It's a measure of how elastic you are, how well you use your tendons, specifically how well they store and release energy which has direct transfer to how high you can jump. So before we get into it if you want us to use these techniques these measurements for your training click the link in the description or in the pinned comment where we can help you find your vertical jump deficit completely for free. It's a no brainer offer make sure you go take advantage of it.

Cool. So when was the first

time you heard of RSI? I heard about it probably closer to first time when you first started coaching me, honestly. Really? Maybe even before. Did you hear it before that?

Maybe. I feel like I

need to hold this because I talk so much quieter than you.

Actually, it might have been around 2020. I remember we did yeah. Because I remember that's when I first did, like, the the hop test and stuff like that. And I had like, there was, like, really recently before that I had heard of it for the first time.

Sorry. The first time I heard of it was 2000, maybe '4 probably because I was in college at the time. So it was probably 2014 or something like that. And it was a it might have even been in a paper about high jumpers or something like that. I don't remember the exact, period.

Maybe Janik, Thomas Kortenbeck used it a lot at the time. Mike Young, my mentor, used it with the elite track and field guys. I know that for sure because he used to do it once a month. They would look at RSI on a jump mat that was, like, really, really sensitive. Basically, like, force plate type grade jump mat.

So as soon as you toe off and touch down Yeah. And it was it was really good for that. Did you use it on a jump mat ever? You never did it on, like, the jump mats?

No. That does remind me it was actually even earlier. I remember the first dunk camp.

It was a dunk camp.

Yeah. They had a Yeah. The RSI.

Had had to have heard it.

Yeah. And that was 2018.

Yeah. You you would have had to have known about it before that. Yeah. So yeah. So what is RSI?

It stands for reactive strength index. Like Isaiah said, it is not a unit. It is an index. It is a way for you to assess where you fall in terms of stiffness. Specifically, what it measures is how well you use the Musculo Tennis unit in rebound jumps.

You can also do it off depth jumps. You can do it on a multi jump test where it's like six reps essentially in succession. Typically, people take the top three reps and average them. But if you have the MyJump two app, sometimes I'll just look at the best rep. The MyJump two app is really good because when you do this test, you have to be very strict about your testing.

I think it's like the the sampling rate. So if you don't have a high sampling rate, meaning you're not collecting data fast enough, then the numbers are gonna be really, really inaccurate. So the iPhone uses 200 frames per sec 240 frames per second, and that allows you to get a sampling rate of at least 240, which is pretty fast. So you can get pretty accurate measurements. I think the app is what, like, $10 or something like that?

Something like that. And that's how we do it. You could also do it by taking your iPhone footage

sponsor us.

Yeah. They don't sponsor us. You could also do it by taking your iPhone footage and filming in 240 frames per second and putting it into, like, a software or something where you could just click through arrows. Yeah. Where you click through the arrows, and one second is 240 frames.

So you could do the math and essentially figure out how much time you're in the air versus how much time you're on the ground. And that's essentially how you calculate your RSI is your flight time over your ground contact time. So when this or the utility of

it I also wanna add Yeah.

Go ahead.

My favorite place to measure it is on a approach jump. Yeah. Because the what I don't like about the repeat test is you can change your technique to game it a little more Which I'm good at. But I haven't found it to be like a good indicator. Like, it doesn't transfer as well to your training.

However, if you're doing a max approach jump where the goal isn't, you're not trying to like maximize your RSI, you're just trying to jump as high as possible and then you see how that number changes over time, I think it's a lot more useful.

Yeah. I I do agree with that. It tells you how stiff you are in a takeoff. So if your ground contact times are really, really low and your flight times are really high, and that's happening as a happening at not because you're trying to do that, but as a consequence of your jump strategy, then I think it's really, really useful. Like for Isaiah, we typically look at it specifically with the ground contact time, and we are always considering the flight time so we know what those bandwidths are.

Like for him, I know if he's between nine four and nine nine in the air, his landing mechanics don't really change that much. We also take that into account. So if I know that he's landing really high, I pretty and I I can tell based on on a height check how high you get your head above the rim, and I'm really good at telling him, like, oh, this was your flight time. And I can pretty well tell based on how high his head is above the rim and the landing configuration that he's in.

And I can tell from two, like Yeah.

Being in the air.

Where the rim look like, where it looks like it's in the air compared to my face, I'm like, that was nine four. That was nine five.

Yeah. And then what's really interesting is when you look at the ground contact times. So on your best jumps ever, you're two I think two five. Two fives, two sixes. So, like, in the two fives, two sixes, meaning point two five seconds on the ground.

And then

flight time nine eight. Super fast, and then the flight time is point was it nine nine or 98?

98. 99 is my best ever. Let's call it 985. Okay. And then do right about point two six.

So our size

3.78. And if you look at someone like Dak, his is actually quite a bit lower. He spends a lot longer on the ground.

I mean, his would be probably similar flight time.

Similar flight time. So point, yeah, point nine

eight five. Divided by point three what was it? Three one? Three one. I think

just do three one. I think it might I don't think it was that long.

Think it was. But Really? Yeah.

So three one. But in an RSI test, he would do incredibly well. Yeah. Which is really interesting. So how you

use That this might be a technique.

Yeah. I I think it is. Yeah. So jump 55? Yeah.

You could say maybe Back. Maybe. So RSI is really good because it assesses how well you use the stress shortening cycle. It's essentially assessing when I put more energy into the ground or I'm throwing you down into the ground, how well do you handle that energy eccentrically, isometrically, and concentrically? How much energy do you get back when you're using a lot of gravitational energy, you know, move kinetic energy into the ground, how well can you use that energy to push you back upwards into the air, which is really important when you're looking at jumping because jumping is taking a horizontal energy, kinetic energy, and taking it upwards.

So in the case of RSI jumps, the the difference between the two is that it is strictly vertical. You're not using any horizontal momentum versus an approach jump, you're using that horizontal momentum. And so that's why we look at RSI with specific jumping because what traditionally happens is as Isaiah were to get to that 51 or 52 inch vertical, he needs to have those contact times trending downwards. If he's jumping point nine six, but his ground contact time is, like, two hundred and eighty milliseconds, then we know that there's a big deficit there, that he's not able to store and release energy really, really fast. And the faster you store and release energy, the less it dissipates his heat.

We we've also seen that on an approach jump, the ground contact time is inversely related to your approach speed. So it's like pretty much without fail, the faster I run, the shorter the ground contact time gets. But depending on how I am physiologically at that time, sometimes I'll jump lower by running faster.

Yeah. You have to be able to use the energy. And I think that's a big caveat, and that's why you look at both. Because, yeah, you could artificially, you know, decrease your ground contact time. You could try to run faster or spend less time on the ground.

Short to penultimate.

Short to penultimate, but then you're not gonna be jumping very high. So it's important that you look at both of those because the outcome we're really looking at is jump height. So you wanna see jump height go up, and you wanna see the contact times come down. You don't wanna see jump height go down as a result of decreasing the contact times. That's generally not gonna be the outcome you want.

It's gonna train you to be on the ground shorter and not apply the maximum amount of force over that time interval that you have. Typically, guys won't lower as much when they do that. They I'm trying to think. That's probably the biggest way. They'll they'll run really fast and not lower at all, and you can artificially, basically, decrease your ground contact time, which, again, is not what you wanna do.

Have we looked at my RSI on a one foot jump ever?

Yeah. I think we have. You're very similar to me on a one foot jump.

Point I mean, I'm around my best jump ever is probably, like, point eight eight.

Yeah. One one foot jumps, you depending on how you land, it, like, massively changes your flight time. And then your Our cycle is up. Ground contact time is real your ground contact time is shorter than that for sure. Really?

Yeah. So one foot jumps the the problem with one foot jumps is your flight time is usually lower because you're landing in a really high configuration, but you're also taking off in a high configuration.

Yeah.

So in a sense, it's like kind of corrects for itself. You land in a similar configuration to what you took off as, where, again, two foot does kinda same thing. That's the benefit of one foot jumping. You can get more of your mass higher. But somewhat tangent to the point, when you're using RSI as a metric over time, let's talk about how you can essentially assess the deficit.

So the two things that I would typically look at, specifically from one foot jumpers, I I do like to look at repeat repeat drop sorry, repeat jump RSIs.

Then because and it's because the range of motion and the ground

contact times. Very It's very specific. And then when I'm looking at two foot jumping, I'm typically looking at the ground contact times. I will also track RSI over time. But as you get more elite, I found that that correlation drops off really, really fast.

So it's good to tell readiness, and it's good to tell, you know, preparedness or how fit you are.

And if someone has a huge deficit Yeah. Exactly. Good. So Like like Amruth actually is a good example of that.

Right. So, like, Amruth is an athlete that we coach. This is a good example of this. His RSI when he started with us, I think, was, like, 1.3. It was really, really bad.

Good would be, like, in the high twos. Low threes is really, really good. If you're in the high threes to fours, you're probably a world class high jumper. You're probably, like, very, very, very elastic to get those numbers. Like, Cami Colville has one of the highest RSIs I've seen in repeat hops.

It's also height dependent. So if you're shorter and you have, like, a really small foot axis, I've seen that guys will typically test way higher in RSIs. The stiffnesses typically are higher in those guys as well. But when you correct for height, they're equated. So and we also see this in sprinting.

If you're a shorter sprinter, you have to have way higher stiffness than taller guys. So you also have to take height into account. But generally speaking, yeah, if you're a really, really tall guy and you're in those high twos, low threes, you're probably a freak. You have really, really high outputs. If you're a shorter guy, then you're wanna gonna you're going to want to be in the mid threes to high threes.

That's what I've noticed. And that would be someone under, like, five eight or something like that. You're you're gonna have a really, really good RSIs. So what that means in terms of Amroof. Amroof is a shorter guy.

His RSI was 1.3, and he was getting way, way stronger. We saw those RSIs climb up early on in that period of time. But he did this RSI test, and his metrics, again, were not good. Right? His power clean was getting relatively good to his body weight.

His backswat was getting better relative to his body weight, but his RSI was not changing. And as a badminton player, he needs to have RSI. It's probably one of the stronger determinants of his success in the sport as a KPI performance KPI. And so we had him on a protocol with very, very low volumes, and this is similar to what we talked about the other day doing plyos, specifically depth jumps. I think we started we started, I think, at twelve, maybe went to eighteen, twenty four inches and just had him practice doing the test more or less.

And I think he also did repeat hops in there occasionally too. And then after about, I'd say, six to eight months, he actually told us his RSI was 2.3, which is a massive, massive change. And his standing vertical also corroborated those changes, and his approach vertical also corroborated those changes. I think his vertical went up, like, from 18 to 24 or something like that. Yeah.

Maybe 25. So, you know what, he's not a jumping athlete. He's a he's a badminton player, so you have to take that into consideration. But the training that we do for jumpers is gonna help anyone globally. If you're more explosive, you can redirect energy better.

You have to be quick and explosive.

Yeah. It's gonna it's gonna pay off. And you see this all the time. If you watch Isaiah play defense, that's probably, like, the best example of this or myself even. Like, RSI is one of the better determinants of your ability to play defense.

It's I lock the lead athletes up.

I've seen it happen in real time. I've seen them play literally NBA talent. They were high school players at OT, and he was he was he was shutting them down. How hard they were trying? I don't know.

But I think they

were They're also a foot taller.

Yeah. They were a little bit threatened when Isaiah put their put his hand up in their face, and he's got that wide stance, and he's just shifting around like a little Sonic the hedgehog. So so, yeah, if you have those lower metrics like Amruth in RSI and your strength is really good, then that's a major deficit. You definitely need to address that in the form of really, really low volumes of doing the actual test. You need to learn to store and release energy, and that usually will transfer over to the sport that you're playing or jumping or whatever else relatively well.

It takes a little bit of time to transmutate those transformations that you made, you know, in a controlled setting to the court, but I've definitely seen it happen time and time again. And that's really the utility of plyometrics and why I keep them so simple. I don't like to get super fancy. It's in my experience, it's easier just to pick a few good ones that you really like and and stick with those.

What what should someone do if they're bad at everything? So they like, what they have a they're really weak and their RSI sucks.

So this was, not to put Amrith on blast, but he was not strong either when he came in. But the first thing that we did is we drove up those strength numbers. And so his RSI increased as a result. And what happened is he created reserves for adaptation for RSI that he then was able to actualize in the form of a higher RSI by doing the plyometrics.

So the the deficit, it's like it's more you have the deficit if you're really strong and your RSI sucks.

Yeah. That's when you have that deficit. You you if you have a true deficit, that means you're deficient at something. If you're just bad at everything, you don't have a deficit.

You're You just suck.

You're just you just suck. Sign up for TSB. You gotta get better at everything. So then the the reverse of this would be someone like a high jumper. High jumpers, they typically have crazy RSIs, even sprinters in some cases.

But if you looked at their squat jump metrics, if you looked at trying to think of, like, another good one. Barbell squat jump testing, where you're looking at VBT, you're looking at time to peak velocity, you're looking at peak wattages, you're typically gonna see really big deficits there. Know, if you're looking at Isaiah and I are really good examples, actually. His RSI is like 2.7 or something like that. I've hit upwards of three two, three three.

And but if you looked at our power metrics, his peak wattages are way higher. If you put us on an isometric mid thigh pool, my early RFD is really, really good. Isaiah's kinda lags back. But if you give him enough time in the latter part of that curve, you're gonna see his forces just keep climbing over time. And if you put him on a power clean test or something like that, it's it's demonstrated there as well.

Right? He's got a little bit longer time to generate force, and he generates a shitload more force. He can power clean, you know, almost a 100 pounds more than I can on any given day. But if you look at just the early RFD or RSI where you're predicated on producing force really, really fast, he's gonna lag a little bit in that area. And so that's why with him, we had that period of time where we were working on this.

We were working on early RFD because we wanna see that whole curve get steeper and then also go higher. We wanna see him generate more force over that interval of time that he has to generate force in a jump, which is, as we said, about two hundred and fifty milliseconds. So it is a little bit task specific. If you're gonna be in something that you're on the ground for no time at all, then RSI is gonna be a stronger KPI. If you're, you know, in something where you have more time, like a two foot jump or you're a shot putter or you've got I'm trying to think of another good example.

Maybe I don't know. That's those are really probably the best ones. Most sports are predicated on the shorter periods of time. Then it's not as much of an indicator to your success. And then on top of that, there's also technique.

So, like, the last thing would be if you're noticing you've got great RSIs, you're super strong. I see this a lot with bobsledders. They have crazy RSI numbers. They've got crazy strength levels. They've got really countermovement jumps, crazy squat jumps, but they don't jump high in in approach jump.

And in that case, then it's that you haven't been able to transform or transmutate sorry, transmutate any of those gains to actual jumping, and that's where your deficit is.

That's where I was like, even the athlete we we were having a dunk session yesterday, and one of our athletes met up. And looking at his technique, I I actually wasn't coaching it because I don't see a point in improving trying to improve someone's technique like short term like Yeah. Within one sec especially he was trying to get his first windmill. It's like I don't want him to worry about that.

Just jump

higher. But looking at his technique, I was like, wow. Like, if he, you know, really focused on only improving his technique, there's like three, four inches in there.

Like, that wasn't he bad. Like Yeah. The athlete was Joel. Shout out Joel if you're listening to this. But if he were to improve that technique, you know, along with those changes to his to his outputs, he's gonna he's gonna jump away.

Which happens at the time. And he was and he said, like, where he lives, it's winter, so he hasn't had a jump session in a

think it was really that bad too on some of those

lot of like Dom. Yeah. Yeah. It was actually pretty solid. It was yeah.

It some it was more so, like, the consistency Yeah. Of it and then the the speed of the approach too. Like, if he learned how to just, like, run faster and then get the, like, a good timing of that momentum, like, I think he would he would fly.

And there's a lot of ways that you could treat deficits. You could dose it in really, really well, relatively low volumes of just specific work. So for example, if you're really weak, you could hypothetically just do squat singles like three times a week, and you would be able to mostly correct that, or at least get a big chunk of that deficit corrected. If you're someone who's really strong but you don't have any reactivity, it could take you about a month before you could really start to correct that deficit. So there's different ways that you can do preferred way, though, and what I've seen consistently improve people's verticals is in a long conjugate sequence system because you're leaving no stones unturned and the adaptive reserves are way higher as a result of you adapting to all the workload, all the volumes, and, you know, as a result, guys traditionally jump higher.

Like Dom right now is probably a prime example of that. Dom's increasing his force capacity across the entire continuum. He's getting better. He's getting faster. He's getting better at power cleans.

He's getting better at repositioning out of those power cleans. He's getting better at pulls. His squat is going up. He's get he's doing and he's jumping, which is like a major thing. And I've just had him low rooming consistently.

So once those all come to kind of a, you know, a peak or a pinnacle, that's whenever guys really, really pop off. And I think you would agree with that. Right? Like, as your power up obsession soon. And you've had that happen with you as well on long conjugate systems.

Session tomorrow?

You always jump higher. What's that? No. He because well, we don't know yet. I have to talk to him because I don't know how he responded to power cleans yesterday, and I haven't talked to him today.

So I don't know. But when I get back

Who's waiting?

Who's waiting for I know. Dom is Dom is watch. I would say there's a storm brewing, and Dom is, like, in that case.

I can tell. Like, just from because I've been watching his training.

You can when guys start pushing weights, when they start challenging themselves, they start vomiting during workouts.

Any stringing together sessions?

Yeah. That's that's That's like the

rule I mentioned the other day. It's like string together three, four sessions in a row, and then your training has been dialed in during that time. Like

Yep. Keep the sessions short but sharp, and that's when guys jump higher. So that's the podcast, guys. If you're interested in getting coaching from us and having us do this deficit for you, we're currently running a challenge where we will get on a call with you, figure out what deficit you have. You bring your back squat, power clean, RSI numbers, and jump technique.

We run a whole deficit for you. It's completely free. No charge to you. And if you decide to move forward with working with us, you have the potential to earn your money back by increasing your vertical. I think it's two inches in six weeks.

So that is an option for you guys if you're interested in doing that. So little little shout out for us there. Little plug. Yeah. But, yeah, we'll see you guys tomorrow.

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