What is muscle “Activation”?

The Tennis Physio
Jul 29 · 8 min read

Aka: What is “Turning On” what wasn’t really “off” in the first place.

Has anyone else noticed an overuse of the term “Activation”. It’s everywhere.

Physios say it.

Personal Trainers say it.

Instagram Fitness Gurus say it.

Wonder Twins say it.

Therefore, those who listen to Physios/PTs/Instagram Gurus, then say it.

This is what happens when you Google it:

You will find a list of complex, scientific-sounding terms most often used by scientific-sounding people.

Eventually when trying to get a single sentence about what is going on, one will find something like: “Muscle activation is when a muscle is turned on for a task”

So then you will ask…

You will usually find something like this: “A muscle turns on when it is activated”.

So then you Google, “What is muscle activation” and then you end up in an endless pseudoscientific loop of nonsense.

The problem is, when you dumb down things like neuroscience and medicine down so far, it loses all meaning and “Professionals” can start taking advantage of it by making you do specific things for the wrong reasons, and sometimes no reason.

So, I will now attempt the very dangerous and highly challenging task of simplifying what “Muscle Activation” is:

Muscle activation is when you shorten (contract)a specific muscle, and hopefully then relax it afterwards.

…..because muscles shorten and relax that’s their job.

A muscle that shortens, but doesn’t relaxes, is in a state of spasticity. This occurs in Cerebral palsy.

Granted, you can have a weak and strong neural impulse to excite a muscle…. however, popular culture loves to work off False Dichotomies, so you’re probably more likely to hear about “turning on” or “turning off”.

However, as it is impossible to shorten/relax a single muscle (eg: Gluteus Medius) without jabbing invasive electrodes through the skin and fascia and into the specific target muscle and then electrically stimulating that specific muscle, it is much more likely that “muscle activation” is the contracting/relaxing of one or more muscle groups/complexes (eg: Calf Complex -> Gastrocnemius, Soleus, Peroneals, Tibialis Posterior)

Hopefully that attempted explanation of “muscle activation”, a complex neurological, biochemical and biomechanical process, wasn’t too much of a brainsplosion.

…but what about all the stuff the _______therapist (insert a respected profession here) told me? Which I’ve also confirmed via my own Research*

*“Research” — usually Googling with a dash of Confirmation bias.

Rhetorical question #1:

Someone just told me I have “Dead Butt Syndrome”, I’m not turning my glutes on, is this true?

No. Well it depends… if you are dead, then yes. If not, no.

Rhetorical question #2:

If “Muscle Activation” is simply the contracting/relaxing of a muscle group, rather than a specific muscle, do we need to get specific?

No. No we don’t.

For example,a group exercise class instructor telling their class to squeeze their glutes (“tense your buttocks”) in order to contract the glutes (“activating the glutes”) before squatting.

Or another example, a Physio asks a patient to “turn on” their VMO in their quads (which can’t be done in isolation and may not actually matter)

Or, a Pilates Instructor tells their client to “activate” their “weak TA.”(TA = transverse abdominis… probably never a real issue to begin with.)

Or, an Instagram “Shoulder Guru” (already a ‘red flag’) says to do a Lat Pulldown whilst squeezing the bottom of your shoulder blades together to target “lower traps” (because a study on overhead athletes once found that lower traps are inhibited in people with shoulder pain….. which has been quoted when talking about Lower Traps ever since... for normal people... who aren’t overhead athletes.)

And so many more: scapulothoracic activation for all patients with “poor posture”, medial plantar arch(tib post) activation for every “overpronator”, deep neck flexor activation for every sore “turtle neck”, the list goes on, confusing patients, sometimes belittling them and often disempowering them.

All of these muscles are supposedly off/dead/inactivated.

Additionally, it’s important to note that the “core” is activated more during a normal back squat than during a plank exercise or targeted “core activation” exercise, even if you aren’t a skinny female, dressed in colourful leggings (which we all know, is a sign of someone with an excellent “core”…or at the very least, on a never-ending quest to find it.)

So do we actually need to concentrate on “activating” regions of our body before we perform a functional movement:

…..The short answer is: no, not usually, but sometimes, it depends. (The answer that Dr Google should provide for every search of a Complex Healthcare issue)

So why does it “depend”?

Let’s have a look at a population of patients that needs work on “muscle activation” that is specific and also intensive, Stroke patients (aka Cerebrovascular Aneurysm or CVA).

A stroke is an interruption of blood supply to the brain, either from a vascular blockage (ischemic stroke) or from damage to the blood vessel and bleeding (hemorrhagic stroke).

If there is an interruption to cerebral (brain) blood supply for too long it can potentially result in the loss of function of specific muscles/tendons, which makes daily movements such as reaching (for upper limbs) and standing up (for lower limbs) difficult at best, impossible at worst.

Health Professionals who work with Stroke patients focus on ‘muscle activation’ of specific muscle groups for many hours over many weeks, months and sometimes years. The repetition of this task hopefully helps ‘rewire’ the brain to not only “turn on” the muscles (activation) but also activate them appropriately (not too much and not too little) and also ensure they “turn off” or deactivate at the right time.

This training happens every day (whilst the patient is in rehab on a stroke ward) for as many hours as possible over that day that the patient can manage. These patients work their pants off to achieve the most basic of muscle functions, contract and relax, it’s very exhausting.

This retraining of muscle activation also occurs for Traumatic Brain Injury (TBI) patients and also Spinal Cord Injury (SCI) patients, who are often on the same ward as CVA patients, doing the same intensive “activation” rehab. As a Son of a partial Quadriplegic (who met his future wife (registered nurse) at the hospital he was stuck in after his accident, great story for another time) I can personally attest to how HARD these patients work and how competitive they can get during their rehab.

Another cohort of patients who require retraining or “activation” exercises are those who are incontinent, whether due to medical reasons or due to pelvic floor weakness, which can occur during pregnancy (head-nod and high5 to my Women’s Health colleagues).

Ok, I haven’t had a stroke and I’m not incontinent, nor do I have an neurological injury. So what about me, I’m just ‘activating’ things when I do exercises?

Well, what is strength/resistance training for:

1. For a person to improve the efficiency/performance of movements, whether sports related (jumping in volleyball) or just functional (picking something off floor).

2. For a person to reduce injury risk of movements, whether sports related (strength and stability around shoulder in Rugby to avoid dislocation) or functional (trunk and leg strength to pick things off ground to avoid back injury).

…plus many more reasons, but mainly the above two.

But I still can’t feel my glutes when I do a Monster Walk! So obviously I’m not “turning my glutes on” properly.

Well…no…it’s maybe not your fault (patient/client), it’s ours (guru/PT/physio).

We are all wired up different, constructed differently. Sometimes when I give a patient a Monster Walk to do they feel it in their TFL or Hip Flexors, not the Glutes (the aim).

So I (me, not them) have to change the exercise (almost every time) to get the right result for their anatomy. For example, for a monster walk I can use:

  • Band around ankles (and walk in hip/knee flexion or hip/knee extension)

..until the patient finally points at their butt and goes “ouchy, that’s challenging!”

…and yet, again and again I have heard of and seen gurus/PTs/physios poke and prod the patient and yell at them “turn your glutes on” after they’ve given them ONE variation, expecting that it will load the glutes every time.

So… knowing all of the above, let’s answer the below question, which is a real question that popped up in an appointment recently by a patient with sore lateral hips after her gym class:

Should I squeeze my buttocks together (“activate” them) before I squat in a gym class?

No. No you shouldn’t. You aren’t in a clinic. You haven’t had a stroke (hopefully not). You aren’t incontinent (hopefully not, yet).

You don’t need to activate muscles before using them, they might require a ‘warm-up’ (doing a low-intensity movement to optimise neurological and vascular function for a muscle group), but they are definitely not turned off.

So just move.

Whatever you’re about to do, do it with a gradual low to medium intensity involving all the movements/actions you’re about to do at a higher intensity (aka… a warmup).

If you have pain/injury, get it full assessed and rehabilitated by a Registered Health Professional, if you don’t have pain/injury:


Trust in your body to organise what seems to be a very simple movement against load (or gravity), however is in fact a very complex series of neuromuscular, biochemical reactions occurring at microscopic and macroscopic levels. All of which occur in perfect synchrony and harmony, not dissimilar to a beautiful orchestra playing Beethoven……. but you won’t ever hear the conductor asking the Double Bass section to activate and hold a “A-minor” chord before the symphony starts, that would sound terrible.

The Tennis Physio

Written by

www.thetennisphysio.com Player, Physio & Coach.

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