What Does Muscle Activation Mean?

When activated, a muscle’s job is to contract and produce a movement in the body. When the nervous system stops telling the muscle to contract, it should deactivate and relax.

During a strength training workout or gym session, this is going to happen all the time as you complete several and a number of sets. Skeletal muscles contract under activation, there’s an increase in tension and the muscle usually gets shorter (although not all the time), then the muscle relaxes and returns to a low-tension state. Job done.

The term ‘muscle activation’ has become a popular phrase for personal trainers, physios and other fitness types. It’s often used as part of a warm-up routine to get the muscles ready, hence activated, for the working sets.

Muscle activation has also become a term to describe the strengthening of weaker muscles and those that don’t fire and work as efficiently as they should do when required, for example your glutes may not be pulling their weight so to speak when performing a squat.

In a nutshell, the process of muscle activation causes a specific, targeted muscle to contract and then relax again.

Digging a little deeper, muscle activation is all about the neurology behind the movement and contraction. Without going full scale into the science, here’s a good, understandable look into what muscle activation actually means.

What is muscle activation?

Muscle activation basically means contracting the muscle, which of course happens all the time. The difference comes in the intent of muscle activation prior to training or during your recovery.

Consciously activating a targeted muscle builds a stronger connection between the muscle and the nervous system that stimulates it. A stronger connection results in greater intensity and firing of a muscular contraction when you get into your strength workout.

Some people refer to activating a muscle, as ‘turning it on’. There is sense behind this, but it’s a big simplification for all the work that’s going on in your body behind the scenes.

In reality, the physiology behind activating a muscle is incredibly complicated.

biceps and triceps muscles contracting and relaxing muscle activation in action
Image: Muscles activation – Muscles are contracting and relaxing all the time.

What happens when you activate a muscle?

Here’s a quick scientific synopsis of what happens when you activate a muscle.

A muscle is activated when it receives a stimulating nerve impulse from a motor neuron that comes from the central nervous system. This nerve impulse reaches the neuromuscular junction and stimulates the muscle fibres it reaches. Muscle fibres are made up of sarcomeres, the basic contractile unit of the fibre, which are in turn made up of two main protein filaments – actin and myosin. The interaction of these two active structures, via the most popular model of the sliding filament theory, is how a muscle contracts. 

This is the basic chain of reaction but it gets a lot more complex than that when you dig into the cell biology and full neuromuscular chemical happenings.

So, getting back to the original question of what is muscle activation? A muscle is activated and ‘turned on’ when the muscle fibres are stimulated by a nerve impulse.

A muscle will stop being activated when nerve stimulation stops. At this point, the muscle should then relax to its resting state ready to be activated again. Your muscle can also stop contracting when this is no more ATP (energy) left in the cell.

In weaker muscles, the pathways to activating the muscles may not be as well trodden as the more dominant muscle, which is why this needs to be evened out to achieve a fully functioning, efficient and problem-free muscular movement.

A detailled explanation of muscle contraction if you’re interested in learning further.

Why is muscle activation important?

Muscle activation in itself is important as it results in a desired bodily movement. Activating the correct muscles and muscle groups when performing an exercise will result in a more efficient, powerful and stable movement.

Better muscle activation means you will be recruiting more muscle fibres which will help you become stronger and overall more effective at a movement. It also decreases the chances of getting injured as you over-compensate for weakness and lack of activation in another area of your body. Gym-goers may benefit from activating a muscle if they don’t particularly use that muscle group a lot, or if it undergoes longer periods of non-use.

The real importance of muscle activation is to improve the connection between the neurology underlying a contraction and the muscle itself. A better brain-muscle connection.

A better connection pathway equals more effective muscle use and better performance in the gym or when performing a movement. The more a pathway is used by the brain and nervous system, the more efficient it becomes in firing.

If you’re not sure about the whole brain connection, think about this. When people first start trying to build muscle, it usually takes around 6 weeks for any noticeable changes to be observed. Why is this?

It’s during this time when the brain is adapting the body and neuromuscular pathways. Once these neuromuscular routes, i.e. activation routes, have been improved the muscle can then start to strengthen properly and grow.

Main reasons why people want better muscle activation:

  • To warm up a muscle group ready for strength training
  • Better muscular performance
  • To strengthen a weak muscle
  • Reduce muscle tightness
  • Reduce risk of injury
  • Improved coordination and balance
  • Increase blood flow to the muscle

What happens when a muscle isn’t activated properly?

Without the correct muscle activation, you will be limiting your potential to gain strength or increase performance. You may also be creating muscular imbalances within your body, which can have a number of knock-on effects.

When a muscle isn’t activated properly, it usually means you’ll be over-compensating for this lack of activation in another muscle. If a muscle is contracted more than it should be and it becomes overused, it can cause two issues:

  1. Tightness in the overused muscle
  2. Further weakness in the opposing muscle

Muscle activation can be used as an important technique to address this imbalance within the muscle pair by strengthening the weaker muscle, inhibiting the overworked muscle and bringer more balance to the area.

A lack of activation and balance can also cause stability issues. For example, knee stability is greatly helped by strong quadriceps and hamstrings. Studies have found that people with hypertrophied quadriceps and undertrained hamstrings have a greater risk of knee injury due to the reduced coactivation of the agonist and antagonist muscles causing imbalance around the joint.

man performing lateral raise for deltoids shoulder muscle activation
Are the correct and desired muscles activating when you perform an exercise?

How to increase muscle activation when working out?

Consciously stimulating the target muscles prior to a working set can be very effective at increasing performance. In effect you want to neurologically warm-up your muscles before using them properly, so they contract optimally.

There’s no secret formula behind this. No ‘hacks’ here I’m afraid. If you want to activate a muscle prior to a movement, just perform a low-intensity version of the movement whilst consciously thinking about the correct muscles contracting.

This activation warm-up will help to increase blood flow to the correct muscles whilst stimulating the neurological pathway so you can recruit more fibres.

Before a squat, for example, you don’t have to consciously activate (i.e. contract) your glutes before you lower down. Instead, think about the movement, prime your glutes and quadriceps and perform the exercise in a controlled manner. This form of conscious activation will help you ‘feel’ the movement in these target muscles more greatly.

If you aren’t ‘feeling’ the movement in the correct muscles, then you may be compensating for the movement in a different muscle. If this is the case, drop the weight, work on technique and get back to basics.

Best muscle activation exercises and techniques

There aren’t just one or two muscle activation exercises to rely on. It all depends on what muscles you are targeting for activation.

Always think of muscle activation as improving the connection between the brain/central nervous system and the muscle. Improving this connection prepares your muscles (and hopefully the correct ones) for movement, to contract properly, limits imbalances and reduces the chance of injury.

For upper body sessions, exercises such as T-press ups, normal press ups, shoulder dislocations, face pulls, Y raises/YTWLs, and straight arm pull downs are all effective at increasing muscle activation prior to workouts.

For lower body workouts, pre-workout exercises such as single leg RDLs, glute bridges, 90/90 hip stretch, bodyweight squat and hold.

Strength Bible Wrap Up

In conclusion, muscle activation is all about improving the neuromuscular connection between the central nervous system and the muscle.

The goal of correct muscle activation is to get targeted muscles to contract at the right time, then relax again when the nerve impulse is turned off. Improving muscular activation will result in less tightness and weakness, increased strength and better muscle performance.


Baratta R, Solomonow M, Zhou BH et al (1988). Muscular coactivation. The role of the antagonist musculature in maintaining knee stability. The American Journal of Sports Medicine. 16(2):113-22.