First things first, I have an apology to make.  In 2023, I managed to post in 9 of the 12 months – 24 posts in all, so not a bad run averaging two a month.  2024 hasn’t been a great year for writing blogs with only two so far, and it’s already September.

 

Truth be told, I decided to develop myself in other areas of my business from April to August 2024, delving deep into social media marketing approaches and AI using ChatGPT.  That didn’t leave a lot of mental energy left for S&C specific blog writing and I didn’t feel this blog was the right vehicle to write about my digital marketing and AI learnings (but tell me if you feel otherwise and would like to hear about it!).

 

I’m back at it now, and I’ve got quite a few Pacey Performance episodes to review as well as some updates on the APA Method and some of the projects I’ve been working on.

 

In today’s blog I’m bringing you another Pacey Performance Podcast Review.  This podcast came at a great time as I have been reflecting on the APA Method in recent days.  Whenever you onboard a new member of staff (we have recently recruited a new part time and full-time S&C coach in one of our Tennis Academy contracts) it’s naturally a good time to reflect on your keystones or “pillars” of the programme.

 

Episode 502 – Gerard McMahon – “Activation exercises: Are they really improving performance or preparing your athletes?”

In this episode of the Pacey Performance Podcast, Gerard McMahon joins us to discuss “activation” exercises and their role in improving performance and preparation. Activation exercises have long been touted for their ability to improve performance by targeting specific muscle groups and maximizing motor unit recruitment. However, Gerard challenges this notion, suggesting that these exercises, often misunderstood and misapplied, may not be as beneficial as many people think.

🔉 Listen to the full episode here

 

Discussion topics:

‘Let’s set the scene.  What does muscle activation actually mean from your experience and knowledge, and how does that differ to what people actually think it means?”

”Really the neuromuscular system, muscle activation is pretty much it’s bread and butter function.  Muscle activation is a very, very simple function for the neuromuscular system to carry out.  If we’re talking about muscle activation and actually look at how it’s quantified and what it is quantifying, muscle activation is the combination of motor unit recruitment and motor unit firing rate (the number of action potentials discharged by a motor unit).

 

Motor unit recruitment is where we gradually (according to the Henneman Size principle) and depending on how much force we want to create, we recruit generally larger and larger motor units and the firing rate is the number of action potentials discharged that come with that.  The two of those processes control force levels and combined together they are “muscle activation.”

 

If you’re talking about what people understand it to be, it’s a little bit different.  I doubt that they know that that’s how muscle activation is quantified.  It’s one of the first questions I ask people.  They will probably throw out a bit of technical jargon but they don’t actually understand how it’s quantified and what it reflects as a measure.  They might draw parallels with post activation potentiation (PAP) which is a completely different thing.  So I think there is general confusion both around what it is and what specific processes you are referring to as well.”

 

“From your experience, why has this term [activation] found its way into the common language, when clearly the explanation of what it actually is doesn’t seem to come together?”

“I’ve had this conversation a few times with different practitioners, but a couple of us think it might have originated from the sports medicine world potentially, where you have either a clinical population or potentially an athlete population that is injured, or rehabbing and there are with some of those conditions issues with muscle activation.  But, the problem with taking it from the context that is used in those populations, and the way that it is being referred to there, to move that to a healthy population where you are warming up those athletes where there are no issues and anything wrong with, it’s completely superfluous; it’s unnecessary to go down that route because they are healthy.  So I think the practitioners have become seduced by the language, as much as anything.  It sounds really fancy, it sounds as though it is going to be really impactful.

 

If you want to sprint you activate muscles, if you want to stretch your backside you activate muscles, if you want to blink you activate muscles, it’s literally the bog standard function of the neuromuscular system.  It came probably from the clinical world, sports medicine world, it filtered in but it is out of context because a lot of people use it with heathy athletes when it’s completely unnecessary.  We’ve seen it appear in for example a RAMP protocol for a warm-up:

 

• Raise Heart rate
• ACTIVATE
• Mobilise
• Potentiate

 

So coaches are coming across these terms in some of our neurophysiology textbooks with guidelines for working with athletes but again, to me they don’t make much sense in those contexts either.

 

“So what factors affect muscle activation levels?”

“Really if you go back to what affects muscle activation, you have to go back to the fundamental way it is measured and quantified which is a combination of motor unit recruitment and motor unit firing rate (also known as rate coding).  So, if people want to increase muscle activation they have to increase either motor unit recruitment or rate coding or both of those in combination.  Those are the two big ones, there are one or two other but those are the two you want to be looking after if you want to increase activation.

 

The two ways to increase muscle recruitment and motor unit firing rate is:

 

• Muscle force – you have to generate more and more force to drive up motor unit recruitment

 

It depends on the muscle group as well.  If you take the adductor polis in you hand, a small muscle found in the hand full of slow twitch fibres, its motor unit recruitment is maximised (completely maximal) at about 30% of maximal voluntary contraction (MVC).  So only 30% of your maximum effort and you have recruited all of the muscle fibres within it already.  So with the bigger mixed muscle groups that contain a bit more Type II (fast twitch) muscle fibres, they might take a bit higher forces – so you’re probably looking at anywhere between 75-85% MVC for those muscles.  So the large muscles with the bigger motor units (because they contain more muscle fibres) require more force.  Because most sports involve those big muscle groups and motor units (quadriceps, hamstrings, Gluteals etc) that’s going to take higher forces to get up to the maximum recruitment.  The key thing is that it doesn’t need to be a complete maximum force/effort to get all of those motor units involved.

 

Rate coding – motor unit recruitment can be maximised at submaximal levels (most of them are between 50-85% MVC) but actually rate coding is much more important that the motor unit recruitment for the highest forces that you want to produce.

 

• Develop force rapidly – so speed or power.  The control of that is slightly different as you don’t get maximal motor unit recruitment because you don’t have time essentially, to get all of those motor units and you don’t develop maximum force as well.  But what you do do with a fast or powerful contraction is you do get very, very high amount of action potentials discharged (firing rates).   You go through far higher discharge rates during a fast contraction than you do through a maximum isometric contraction, for example.

 

So, in a nutshell, if you want to get high muscle activation the muscle contractions need to involve HIGH FORCES or submaximal forces with a HIGH VELOCITY.

 

So, that’s what your exercises need to look like if you want to attain high muscle activation, by definition.  There are other smaller matters like the joint angle, as the joint angle will change the muscle’s length, and at different muscle lengths there are better muscle activation levels.  So, when a muscle is fully extended, if you take the knee joint for example, when the leg is fully extended activation doesn’t tend to be as high during maximal efforts, or if it’s really flexed like if you’re deep down in a squat, activation isn’t quite as high either.  You tend to get the best activation of the quadriceps in and around moderate to slightly long muscle lengths, that pretty much follows the force-length relationship of those muscles.

 

Muscle temperature has the potential to decrease rather than increase the activation so if the muscle temperature is raised too much you may get a decrease in muscle activation but again the affects of that are not particularly high unless the muscle temperature is exceedingly high.  Joint angle and muscle temperature play very much second fiddle to the big ones which are muscle force and contraction velocity.

 

“In terms of quantifying it, where has this confusion around EMG come into play?”

“EMG is a very useful measure.  That is a global representation of muscle activation, it’s more of a mathematical representation of it more than anything, and it contains (the EMG amplitude that you see, the EMG reading) information both on motor unit recruitment and the motor unit firing rate.  But it is NOT an exact representation of that, because what you need to do to get those numbers out for motor unit recruitment and the motor unit firing rate, is you need to decompose that surface EMG, which is where high density EMG comes into it, where you’ve got mathematical algorithms etc and ways of breaking down and decomposing those signals.  So they’re quite complex and representative but where a lot of people go wrong is in the interpretation of those amplitudes and what those amplitudes mean because they are affected by so many different factors that you have to account for, the underlying physiology and the metabolic condition of the muscle and things like that.  They all affect the neural system so it’s not a very simple, straightforward cause and effect.  You can get changes in EMG without the muscle making any more force, without a change in function.  But you can also get a neural change that does match the function.

 

If you look at EMG I would argue it’s absolutely meaningless without other measures to back it up such as a force measure or something that is able to show you what function changes as a result of that change in EMG amplitude.

 

What comes along with activation, when practitioners talk about how I’m doing this exercise to increase muscle activation, they don’t ever measure it!  You’ll find GPS units, you’ll find heart rate monitors, you’ll find all sorts of different monitoring tools but muscle activation seems to be for some reason that thing that people say they’re trying to do, but they don’t ever try to quantify it using EMG.  But I wouldn’t necessarily try to encourage that anyway, because unless you have a background in it, you need to have such tight controls and processes as part of your EMG methodologies so it is not something you decide I want to start doing tomorrow, pick up electrodes and run with it.  You have to have a very good background because how stringent your EMG methodologies are dictates how good quality data you have and actually what kind of inferences you are trying to make with whatever you’re trying to measure.  So it really is a minefield and also with advances in technology we are still learning a huge amount of things about the neurological system so it’s not the sort of thing you can dip your toe in and use here and use there, you need to be consistent at using it.

 

“EMG shorts, not to throw any companies under a bus, people are probably wanting to replicate what they see in these studies and rank exercises based on activation but what value do they bring?”

“I would argue minimal.  The biggest limitation of surface EMG to begin with, no matter how good you are at  it, it’s based on the skin and the skin can move relative to the underlying muscle, so that’s one thing you have to be really careful with when you’re interpreting EMG because how close you are to the neuromuscular junction changes the EMG amplitude signal on its own regardless of changes in force.  So if your skin is moving at all relative to that, that’s changing the amplitude, not anything to do with the exercise you’re doing.  That happens at the best of time in EMG, so if you have EMG in shorts or a piece of clothing that’s embedded in the fabric, that fabric is also sliding over the skin as well so how you can have any idea or be able to make any valuable inference between what you’re recording through EMG shorts and what’s happening in the underlying muscle when you’ve got skin and fabric sliding all over the place – I don’t think you can make those sorts of calls.  It’s a nice idea but again you have to be aware of the underlying limitations of what you’re measuring and the validity and reliability of those, and if the validity and reliability is poor it’s not worth doing.”

 

“Where has the use of low level activation often using bands pre warm-up come from?”

“That practice did come out of left field over the last 10-15 years and I don’t even remember the last time I’ve seen a warm up without someone using some sort of band.  I think it was probably from the sports medicine world, and this is not me blaming them by the way, it’s just been moved out of context from where it has been used appropriately, to out of context and not used appropriately.  Probably if they’ve had an injury and they’re doing some work around that injury, and the physio and doctor may have communicated that they were using a band to activate such and such muscle, so the athlete goes “oh, I must need a band to activate this muscle,” without being familiar with what the definition of muscle activation actually is.

 

The practice then just falls incredibly short of theoretical rational so again we go back to the practice where the bands are taken out and the exercises are used, I suppose to be clear, the bands aren’t the problem per se.  It’s relative ease or lack of stiffness of the bands.  So some of the bands are quite tough and stiff and not easily stretched.  If you put force and effort against the band that you can barely move, that will activate the muscle okay.  But what we do see in practice often is very, very low resistance bands being used for the exercise that aren’t challenging the muscle to produce force.  They aren’t performed with any speed so again going back to motor unit recruitment and motor unit firing rate, if you do activities that don’t require much force or don’t require much velocity you aren’t increasing muscle activity levels at all, and that kind of defeats the purpose of what you’re trying to do.

 

Following on from that is the specificity of it all.  When we look at a lot of the big gross locomotive motions (jumping, sprinting, change of direction) and we have our EMG research done on those types of activities, those activities get you much higher muscle activation than any of those band activities (60-100% EMG).  Those band activities usually quantify anywhere between 20-40% EMG (clams, monster walks).  If you’re going to running in the game, then run in your warm up to increase your muscle activation.  Why on Earth would you try and do an isolated exercise to replace it when it going to give you a low level of activation.  And if running is going to be part of your warm up anyway and supersedes that band work, again, what has that band work achieved?

 

If you’re coming back from injury and you’re returning to sport you would need to be in very bad shape or have a very specific ongoing injury that is going to affect muscle activation that’s going to require any specific activation.  You should regain in most cases in most injuries full neuromuscular properties back again.”

Top 5 Take Away Points:

1. Definition of muscle activation – the combination of motor unit recruitment and motor unit firing rate.
2. Two ways to increase muscle recruitment and motor unit firing rate is: generate more force, or develop (submaximal) force rapidly.
3. EMG – make sure you back it up with a measure such as a force measure or something that is able to show you what function changes as a result of that change in EMG amplitude.
4.  Measure what matters – when practitioners talk about how I’m doing this exercise to increase muscle activation, they don’t ever measure it!
5. Bigger is better – big gross locomotive motions (jumping, sprinting, change of direction) and we have our EMG research done on those types of activities, those activities get you much higher muscle activation than any of those band activities (60-100% EMG).

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 favuor 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

=> Follow us on Facebook

=> Follow us on Instagram

=> Follow us on Twitter