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Back view of attractive portrait man lifting dumbbells with bothWe’re getting into the myth-busting side of our mission this week with a big one that’s been circulating for a long time: The need to cue muscle activation during an exercise.

The idea behind this practice is that we can help increase the strength gains for a muscle by consciously tensing it during a movement, really flexing to put all of its fibers to work as we move a load. Now, this sounds pretty good, but there’s a catch — it isn’t actually how muscle strengthening works.

We don’t recommend cueing muscle activation because there’s no evidence it helps build strength. In fact, the evidence tells us that the movement is less efficient because you are working harder to complete the same movement.

We’ll get into that in more detail, but first, let’s take a quick step back.

The first reason we don’t recommend cueing muscle activation is that maybe your student just doesn’t know where the muscle is that you’re talking about. A dedicated fitness buff might know exactly what you mean when you name a muscle and ask them to activate it, but many of your clients won’t. Making that request during a session calls for a student to turn their focus inward, which means you’re reducing their attention on learning the skill of the exercise. That’s not what we want.

Secondly, and back to the point we lead this post with, the mechanical process of strengthening a muscle doesn’t jibe with the logic of cueing activation. The most basic way to describe this process is to say you have to pull on a muscle quite hard to stimulate it to get stronger. This is ultimately what we mean when we talk about applying tension. And no matter how you consciously activate a muscle, you just can’t get away from this need to actually give it a load to lift.

Looking at some anatomy, we can say that your average muscle is going to have a tendon and muscle fibers, perhaps thousands of them, which run parallel to each other. When you activate a muscle, you’re really hitting the “on” switch for these fibers, which are binary in the sense they’re either activated or not, with no levels in between. What can be moderated is the number of fibers that are turned on, which is essentially what you’re doing every day while dialing strength to, say, lift a coffee mug or a dumbbell.

You might activate a muscle to 10% or 80% tension, respectively, to move either of those things, which really means you’re activating that same percentage of the muscle’s fibers. It’s important to note here that fibers activate in sequential order, so if you’re doing an exercise that requires 10% tension, it’ll only be those same entry-level fibers being used over and over again. They’re the first off the bench and getting heaps of work, so they’re as strong as they’re going to get, but the other 90% of the fibers are only getting used if you’re applying more tension — usually by lifting heavier weights.

So if an instructor tells you to activate all of your muscle fibers, you can do that by flexing, making that muscle tense. However, and this is the main thing, if you’ve only got enough load to get 10% of those fibers actually working, then it doesn’t matter that you’ve activated the rest of them. They still only have insufficient levels of mechanical tension, which means they’re not getting stronger. To truly get high levels of tension across all the fibers, you either need to do many reps or just start with something a lot heavier to recruit more fibers right away. Loading it up is a far more effective means of strengthening, however.

We’ve been addressing this and other big questions of the Pilates field through our AMA (short for Ask Me Anything) series and our Pilates Elephants podcast, but we’re always happy to field more of your musings, wonderings and head-scratchers. Get in touch with us through our social channels or email to let us know what’s on your mind!