This blog is a review of the Pacey Performance Podcast Episode 227 – JB Morin

JB Morin

Website

Background: 

Jean-Benoit Morin, often known as JB Morin, is a full professor at the University of Nice in France.  He has a PhD around sprinting and sprint mechanics.

 

Discussion topics:

 

JB on the contrast between academic research and real life

”It’s very, very important to me to go and see people at the elite level, to see the real life issues, and the real life context.  In my opinion, it’s a way to ask better questions, it’s a way to challenge what we do, and it’s a way, I think, to better design what we do.

 

The main issue is that when people work with athletes, they work with individuals, and they work with individual changes in everything.  When they read research they see group results, and we all know that group results can be influenced by individual variability.  For example, you can see some group results that totally contradict some of your single player’s behaviours.  Sometimes applying the group result to a single player might not be effective.”

 

JB with an overview of what Force-Velocity Profiling is:

 

1. High Force- Low velocity
2. Mod high Force- mod low velocity
3. Mod high velocity- mod low force
4. High Velocity- Low Force

 

 

”What we call profiling means building and assessing the individual spectrum of the force output at various possible velocities of motion.  We know that every load, every velocity is associated with a different level of force output.

 

What we understand from the F-V spectrum analysis is that if you analyse performance through a single load velocity condition, like you do a jump test or a 30-metre sprint, you only have one point of information.”

 

JB on some of the tools and simplified methods to monitor accurately in field conditions

• My Jump app
• My Sprint app

 

”With my friend Pierre Samozino we published some equations that allowed us to profile people out of the laboratory, and we confirmed these equations against reference devices.  Then some Spanish colleagues designed some Apple apps to measure the input easily in the field.  One of these is My Jump, the other app is My Sprint.  I have absolutely no conflict of interest.  I make zero money on what they sell.

 

 

These apps only measure accurately the inputs that are needed for our equations to calculate the mechanical outputs.”

 

JB on how to develop an optimal profile for horizontal or vertical force velocity

”We have computed the optimal profile.  The idea is very simple.  You can have the same 30-metre time with very different force-velocity spectrums.  And our question was does the force-velocity spectrum influence your performance, because we know that for the same Pmax we can have different profiles.

 

I can say now that yes, there is an optimal profile for sprint performance.  It depends on the distance you want to optimise, so it will not be the same for a 20-metre than for a 60-metre.  And so depending on your actual profile and the optimal profile we calculate, we have a better way to individualise the training.

 

 

The funny thing is that we have taken the 40-metre distance, and the actual profile of Usain Bolt, and we concluded that for his world record his F-V profile for that distance was not optimal.  It means that by having a different profile than he had, he could have run the first 40-metres faster.”

 

JB on what the Force-velocity profile actually looks like 

”The analysis of the profile is velocity based force output.  Basically in sprinting and jumping, the profile looks linear.  It’s clearly linear even if the muscle cells or the muscle fibres have a hyperbolic F-V profile.  But when you do a global multi-joint exercises it’s linear, and so it goes from your maximum theoretical force output, down to your maximum theoretical velocity output.

 

 

Then, our approach is to say where is your weakness on that curve? For example, if you’re someone who does only five 10-metre sprints, like a basketball player, maybe if you have a weakness on the V0 end, it’s not going to be a big issue because your sport doesn’t require a high V0.  If you are the same guy with the very same profile but you’re a 100 metre sprinter then yes, you will need to work on that.”

 

JB on Resisted sprints and where we are at in terms of the research

”If you use zero resistance, you will sprint for a couple of seconds close to your V0 and then the higher the resistance the closer you will sprint to your F0.  Resistance is a way to set the running velocity, because there’s a clear relationship.

 

Research wise until 2017, there had been some research on resisted sprints, but only 10% body mass let’s say.  I will not talk body mass, I will talk decreasing speed.  So 10% decreasing speed, or 20% decrease or maximum 30% decrease, and there was no research on other parts of the spectrum.  So it means the complete left side of that spectrum, even the middle side had not been investigated.  And even to date, there’s only one single study using loads that decrease your velocity by more than 70-80% which we call ‘heavy sleds’ or heavy loads.

 

The problem with using percentage of body mass is that it can lead to very different resisted forces according to the surface, for example dry versus wet turf or concrete versus grass.  So it’s better to calculate as a percentage of velocity decrease. But to do that, we need to measure velocity. The best way is to set the load as a function of the decrement in velocity we want to observe.”

 

JB on how resisted sprints can effect athletes mechanically in terms of what their actual sprinting will look like

”We need to be very careful between acute changes, which means how they run while pulling that resistance, and obviously some things change.  Yes of course the running pattern will change when you pull a heavy load.  But the big question is not acute changes.  It’s chronic changes. And to date there has been no study on heavy loads and how the sprint pattern changes.  How do the acute changes interact with sprint performance?  What do we want? We want people to run fast, okay? We have to put that as a balance between changes in sprint kinematics and changes in sprint performance”

Author opinion:

I’ll break scientific convention here for once and speak in first person!

 

I have personally listened to JB Morin speak in the UK on three separate occasions and I have used the Force-Velocity profile with one of my athletes. Even after listening to the presentations, this podcast and reading the journal articles I’m still not 100% clear but one of the key concepts I have needed to get my head around is what JB means by ‘optimal.’

 

Where I think we have got things confused (or at least I have), is in terms of where certain types of activities fit on a Force-Velocity curve,  Below is an example of one of the more accurate interpretations in my opinion.  I say this because it puts jumps closer to the middle of the curve.  If you’re not convinced just look at the velocities of sprinting versus jumps.  Jumping take off velocity is much slower than sprinting velocity.

 

 

My understanding is that we can assume that for most athletes doing a squat jump or countermovement jump, the ‘optimal’ jump performance should occur at their own body mass.  If it doesn’t it’s because they don’t have the optimum balance between force and velocity qualities.  In my head I am visualizing a body mass squat jump as being roughly in the middle of the F-V spectrum and so intuitively it requires a balance of force and velocity to perform it well (otherwise it wouldn’t be in the middle)!

 

Furthermore, the relative difference between actual and optimal represents the magnitude and the direction of the unfavorable balance between force and velocity qualities.  The goal of training therefore is to identify the imbalance (Force Deficit or Velocity Deficit or Well-Balanced) and then carry out an individualised training programme that will target different parts of the F-V curve.

 

A word of caution: A Case Study

 

I wanted to give you a bit of real world feedback on my experiences of using the spreadsheet that JB has made available on his website.  A bit of background, I asked my athlete who is a 60kg female elite athlete to do this test early in her winter training and again towards the end of it.  During the same week she did a 1-RM prediction of back squat using a Gym aware with submaximal loads up to 85% 1RM.

 

I also used a Carmelo Bosco formula (which was inspired by my reading of Jeremy Sheppard’s work) to determine what percentage of her body mass squat jump height she could reach with 50% (speed-strength) and 100% (strength-speed) of her body mass loaded on her back.

 

Initial findings:

Initial feedback from the squat, the Carmelo Bosco formula and the F-V profile (34% of the optimal) was that she was Force Deficit. So I spent the winter period making sure there was a strong emphasis on maximal strength.

 

When I did my analysis of the training block I was delighted that she had gone from 107kg to 141kg back squat, her speed-strength percentage had shifted from 57% to 61% (65% was the target) and the strength-speed percentage had shifted from 13 to 23% (35% is the target).  We still have a way to go but a 10% improvement of strength-speed was great in my book.

 

When I did the F-V profile re-test it only went from 34% optimal to 38%.  I was perplexed!!!!

 

Thankfully JB was kind enough to take a look at my spreadsheet and the first thing he said was- ”Daz- you cannot use this data unless the R2 value is at least 0.95.”  All the validation studies required this level of correlation.  JB said that in the piloting period he found that in less well trained athletes such as some of the youth volleyball players he worked with they also had lower R2 values and a lot of this was to do with poor technique.

 

Looking back, my athlete was not doing lots of heavy squat jumps in the training so her main exposure to the task was during the actual testing.  JB said he was confident that without looking at the video he would imagine that she did not perform the exercise well with loads.  So it didn’t allow you to see the improvement in her F0 that was probably there.

 

He also highlighted that she didn’t have a nice enough spread of loads.  In one instance where she attempted four loads, the final load was too close to the penultimate load so this creates a bit of noise.  In the case of the re-test, she did attempt 100% body mass but because her technique wasn’t great, the extra spread in data was most probably offset by poor mechanics!

 

So the lesson is check your R2 values and to ensure they are very high, make sure the athlete is very competent in the task, and the loading is spread evenly across a range of loads.

 

Top 5 Take Away Points: 

1. Individualisation– new approaches to academic data analysis should consider the group response and also the individual response
2. Build a profile of the athlete– don’t just look at split times and jump height, look at how they sprint and jump and use a F-V profile to see the imbalances!
3. Resisted sprints– set the load as a function of the decrement in velocity you want to observe
4. Valid data is key– the correlation R2 value needs to be 0.95 for meaningful interpretation of the F-V profile
5. Decide what’s important– Do you want technically perfect athletes with a consistent sprint technique or faster athletes? Any acute disturbances in mechanics from resisted loads must be balanced with long term improvement in sprint times!

 

Want more info on the stuff we have spoken about?  Be sure to visit:

Email: [email protected]

 

You may also like from PPP:

 

Episode 372 Jeremy Sheppard & Dana Agar Newman

Episode 367 Gareth Sandford

Episode 362 Matt Van Dyke

Episode 361 John Wagle

Episode 359 Damien Harper

Episode 348 Keith Barr

Episode 331 Danny Lum

Episode 298 PJ Vazel

Episode 297 Cam Jose

Episode 295 Jonas Dodoo

Episode 292 Loren Landow

Episode 286 Stu McMillan

Episode 272 Hakan Anderrson

Episode 227, 55 JB Morin

Episode 217, 51 Derek Evely

Episode 212 Boo Schexnayder

Episode 207, 3 Mike Young

Episode 204, 64 James Wild

Episode 192 Sprint Masterclass

Episode 183 Derek Hansen

Episode 175 Jason Hettler

Episode 87 Dan Pfaff

Episode 55 Jonas Dodoo

Episode 15 Carl Valle

 

Hope you have found this article useful.

 

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• If you’re not subscribed yet, click here to get free email updates, so we can stay in touch.
• Share this post using the buttons on the top and bottom of the post. As one of this blog’s first readers, I’m not just hoping you’ll tell your friends about it. I’m counting on it.
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This blog is a review of the Pacey Performance Podcast Episode 204 – James Wild

 

James Wild

Background: 

James is the Technical Lead for Performance at Surrey Sports Park.  He is also contracted to work with Harlequins to run their speed and agility programme for their first team squad.  He teaches at the University of Surrey, heads up the athletic development for England Women’s Lacrosse and is also completing a PhD in Biomechanics and motor control of accelerative sprint running.

 

Discussion topics:

 

James on his approach to training in terms of speed for sprinters versus team sports.

”Ultimately sprint performance is determined by optimising our ground reaction forces.  Ground reaction force production during stances is pretty complex and it’s influenced by multiple physical qualities and coordination.

 

There might be a little bit more of an individualised approach that can be taken to impact team athlete’s sprint performance.  This is especially true as the positive effects of a more general strength programme diminishes as the athlete grows in terms of their training age and level of expertise and their strength levels.  I think there’s more scope within a team sport setting to impact on an athlete’s speed compared to a sprinter who that’s all they’re training for.  I think it’s a little bit more untapped.”

 

James on the four main areas he is most concerned with to help him build up a profile of the athlete and their sprint performance

 

1. Current sprint strategy
2. Injury history
3. Strength related qualities
4. Actual sprint performance- split times

 

”In terms of the sprint strategy this concerns some of the key technical markers and higher order kinematic variables such as step velocity, step length, step rate, contact time and flight time and how these variables change across the acceleration phase.

 

You can have different ways of being fast over the first 10 metres.  It will probably be achieved in about seven steps, and you would expect to see that contact times will reduce with each step and the flight times will increase with each step.  In the initial steps the contact times will remain longer than the flight times.  This makes sense because we know that we need to generate large amounts of horizontal ground reactions forces to produce the horizontal impulse necessary to accelerate in those initial steps, and we can’t produce that force whilst in the air.  Because of its importance it is possible that someone with shorter contact times (which could increase the number of steps) and someone with longer push-offs could achieve the same overall net horizontal impulse and therefore both be equally effective strategies.

 

It becomes a problem when it is too extreme, so if someone is really chopping their stride and producing really short contacts at the start, and they’re not going to be spending enough time generating that horizontal impulse on the ground.

 

In terms of strength related qualities there are three main assessments I use:

 

• Hip extensor torque assessment
• Squat jump Force-Velocity profile
• Repeated jump assessment

 

The hip extensor contribution to the horizontal ground reaction force production is pretty well recognised now largely thanks to the work of J.B.Morin. It plays quite a key role in accelerating the centre of mass forward during the first stance phase.  I look at peak torque and also the rate of that production.  It helps me to identify whether we might need to slant the training more towards max force type work or more rate force type work with regards to the hip extensors.

 

I’ll also look at two angles around the hip; a more extended hip position for the more later stages of acceleration and top end speed, and then I’ll have a much more flexed hip where less emphasis is hamstring driven, it’s more towards the glutes related to the earlier stages of acceleration.

 

 

The squat jump force-velocity profile follows the methods of Samozino and his crew.  We can work out peak power of the leg extensors, and it’s a bit more biased towards the knee extensors.  We can look at the optimal levels of force and velocity that might be required at a given peak power to maximise that push-off performance that might be related to those initial steps.

 

This allows us to then tailor our squat-based pattern work to be more max force orientated, more force at higher velocity or concurrent  development of both.

 

The third strength quality assessment I use is like a repeated in-place jump test for RSI. This allows us to get an idea of how they’re able to limit the amount of leg definition, so stiffness but also looking at how they’re able to store and release the elastic energy effectively.  Once they’ve reached a certain strength level I feel like it’s quite important to become a little bit more specific with the approach taken.”

 

James on how he designs a training session using the profile information

I divide my speed sessions into five different sections

 

Drills:

• Low intensity activities
• Cyclic in nature
• Aimed at reinforcing favourable body position, rhythm and timing

 

Drills for me can be a really useful coaching tool, in my opinion, because they allow you to almost over-emphasis an aspect or body or limb position you’re hoping the athlete will find when they sprint.  And the athlete can then ”hold onto” what that over-emphasis feels like.

 

Jumps:

• Selection decided based on theme
• Usually more horizontally dominant for acceleration
• More vertically dominant for max velocity
• Continuum for regression/progression

 

 

Priming activities:

• Pretty much sprinting
• Resistance sprint work (acceleration focused)
• Running over small hurdles (max velocity focused)

 

Free Sprinting or change of direction:

• Close to maximum capabilities
• Gradual increase to the distances covered and speed reached over time
• Athlete ideally needs to be fresh

 

Sport specific speed:

• Match conditions with constraints
• Gradual increase to the distances covered and speed reached over time

 

”The stage of the season or the logistics of that week, and individual needs of the players, will determine how many of those five components will be in an individual training session.  In a typical 45-minute session I’ll usually cover four to five of those components.  Whereas if less time is afforded such as towards the season, we might need to pick and choose from those five components which we feel are the most important at that time.”

 

James on protecting hamstrings

”I think one of the things to consider is that sometimes a hamstring injury just happens!  And we can over analyse it and pull things apart programme wise.  I think gradual exposure and progressive exposure to sprinting distances and speeds is important.  Tied in with that is the technical focus of how they sprint.  Then I think inevitably there needs to be some strength-based work for the hamstrings, eccentric and isometric and I have no problem whatsoever with nordics.

 

I think it’s really quite important to consider the strength qualities around the ankle.  Do they have the reactive strength type qualities, the stiffness with the right level of compliance at the ankle joint? Because, if they don’t, then they most certainly are going to over stride when they sprint, and over utilise the hamstrings.  Their strategy to run fast is going to be to over utilise the hip extensors to pull them through the start phase, rather than striking closer to their centre of mass and being able to spring off quicker as a result of a stiffer and tight ankle.

 

Also what’s their lumbar and pelvic control like? Are they weak through certain areas? Are they just lacking coordination? Can they not stabilise their pelvis because of, it might be simple things like the hip flexors want to take over everything, are they not able to counter that through their abdominals?”

James on coaching cues for improving sprinting performance

”Often for each individual they might need a combination of different cues that work for them. A lot of S&C coaches fall into the trap of seeing that their sprint technique has ”improved” and automatically think that they’re running faster.  I can tell you that 99 out of 100 times, in that acute setting , if you cue someone and they change their technique from how they normally sprint, they will be running slower.

 

Now that’s absolutely fine if that’s part of a longer term strategy to try and shift them towards a certain technique.  But I think we just need to be a little bit cautious in that they will be running slower in that acure situation.  I think that sometimes it’s necessary to explain to the athlete that during a match or during testing or whatever, at a key time where they have to run as fast as possible, don’t think necessarily about changing your technique.

 

Now there might be a flipside to that, that if someone’s a real injury risk waiting to happen, then obviously you might want to adapt it.”

 

James on why S&C coaches are not as comfortable coaching speed as they are strength

”It completely makes sense, because if you think all those individuals, the amount of time they’ve spent training would have been more in the gym than it would have been out doing speed-related stuff. Then you consider that not all but a lot of educational programmes, degrees, courses out there, there’s probably a lot more emphasis on strength training as there is to speed.”

Author opinion:

Assess don’t guess!

It is clear that James has developed a very comprehensive assessment battery and has a very high knowledge of the sprinting technical model and the various components of an optimal sprint strategy.  What was most interesting to me was the idea that in some cases it might be more optimal for an athlete to take more steps than the typically reported seven steps over 10 metres -provided an athlete can achieve the overall net horizontal impulse required.

Clearly in order to know this for sure James is able to measure specific variables such as step velocity, step length, step rate, contact time and flight time and build up a profile that isn’t just based on outcome measures of split times.  He also uses a comprehensive strength assessment of not just leg extensor strength but hip extensor and ankle stiffness.

Top 5 Take Away Points: 

1. Individualisation– the higher the level of the athlete the more important it becomes to have an individualised approach to improving sprint performance
2. Build a profile of the athlete– don’t just look at split times, look at how they sprint!
3. Little by little– gradual increase to the distances covered and speed reached over tim
4. Technique timing– if you cue someone and they change their technique from how they normally sprint, they will be running slower
5. Understand Key Technical aspects of Sprinting– in order to get more comfortable coaching speed then get out on the field more and actually coach it, train it yourself and understand the technical model.

 

Want more info on the stuff we have spoken about?  Be sure to visit:

Email: [email protected]

 

You may also like from PPP:

 

Episode 372 Jeremy Sheppard & Dana Agar Newman

Episode 367 Gareth Sandford

Episode 362 Matt Van Dyke

Episode 361 John Wagle

Episode 359 Damien Harper

Episode 348 Keith Barr

Episode 331 Danny Lum

Episode 298 PJ Vazel

Episode 297 Cam Jose

Episode 295 Jonas Dodoo

Episode 292 Loren Landow

Episode 286 Stu McMillan

Episode 272 Hakan Anderrson

Episode 227, 55 JB Morin

Episode 217, 51 Derek Evely

Episode 212 Boo Schexnayder

Episode 207, 3 Mike Young

Episode 204, 64 James Wild

Episode 192 Sprint Masterclass

Episode 183 Derek Hansen

Episode 175 Jason Hettler

Episode 87 Dan Pfaff

Episode 55 Jonas Dodoo

Episode 15 Carl Valle

 

Hope you have found this article useful.

 

Remember:

• If you’re not subscribed yet, click here to get free email updates, so we can stay in touch.
• Share this post using the buttons on the top and bottom of the post. As one of this blog’s first readers, I’m not just hoping you’ll tell your friends about it. I’m counting on it.
• Leave a comment, telling me where you’re struggling and how I can help

 

Since you’re here…
…we have a small favor to ask.  APA aim to bring you compelling content from the world of sports science and coaching.  We are devoted to making athletes fitter, faster and stronger so they can excel in sport. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics. — APA TEAM

 

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