Muscle Memory and Gym: Can you rebuild lost muscle?

muscle memory

There are times when regular gym-goers take long breaks from the gym. Whether it’s a nasty injury, a long holiday or a change in priorities, such a lay-off is common. After a couple of months, your muscles shrink smaller and your strength diminishes. Does this mean all your hard work was for nothing? No, not at all.

Aside from the holistic benefits you attained during that period of growth, your muscles also underwent physiological adaptation. And this lays dormant for years. This change is more commonly known as muscle memory.

So what is muscle memory? How does it work? And most importantly, how is it relevant to the gym? Read on to learn everything you need to know. 

What is muscle memory?

In the context of gym and muscle growth, muscle memory refers to the phenomenon that it’s much easier to regain lost muscle mass than it is to put on new muscle mass as a beginner.

Studies demonstrate that after a period of detraining, people who had previously undergone resistance training were able to regain their muscle strength more quickly than people who had never trained before. 

Let’s say you train for a number of years, gaining mass and strength as you do so. Then you get an injury which prevents you from training at all for three months. In these three months, you will lose a large amount of your muscle and strength. However, when you return to the gym, you regain muscle and strength very quickly – much faster than when you initially built it. This is because of muscle memory.

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How does muscle memory work?

Improved coordination

The first reason muscle memory occurs is due to the CNS (Central Nervous System). When a person performs a certain movement or exercise repeatedly, their CNS learns how to perform that movement more efficiently. 

By forming neural pathways that make it easier for the brain to send signals to the muscles, it allows for improved muscle activation and coordination. As a result, the person performs cleaner, more meaningful reps, getting more bang for their buck than a beginner might. 

This is the same idea about learning to ride a bike, drive a car, or play a musical instrument – the long-standing neutral pathways exist, and the person is able to pick it back up more quickly.

Increased myonuclei

For a long time, the CNS was believed to be the sole reason for muscle memory. However, there’s another even more powerful reason behind this incredible phenomenon: the maintenance of myonuclei, despite atrophy. 

In a groundbreaking study by Brussgard et al in 2010 [1], it was discovered that the myonuclei we build during an initial stage of training remain, even if the muscles themselves grow smaller. These myonuclei are then re-awaken once training resumes, accelerating the growth of your muscles back to their previous state and beyond. Not only can we execute the reps better with our neural pathways, but our muscles respond more quickly to the training. 

Let’s explain these phenomena more deeply, with the latter taking precedence. 

Muscle memory and myonuclei

 

The factories of muscle cells

When you begin resistance training, your muscles respond by becoming stronger and bigger in order to adapt to the new stimulus. At a cellular level, one vital aspect of this is increasing the volume of myonuclei. 

Myonuclei are the nucleus of muscle cells (or muscle fibres). They contain the genetic material that controls muscle growth and repair. The number of myonuclei in a muscle fibre determines its ability to grow, as more myonuclei allow for more protein synthesis, which is necessary for muscle growth. 

The process of resistance training leads to muscle damage and inflammation, triggering muscle repair and growth. As muscle fibres do this, they require new myonuclei to support the increased protein synthesis needed for muscle growth. Think of them like little factories in the cell that work to increase production and size.

The myonuclei are supplied by the satellite cells. These satellite cells can differentiate and fuse with the damaged muscle fibres to provide new myonuclei, leading to muscle hypertrophy (increase in muscle mass). This process is called myonuclear addition. So, rather than saying you’re chasing gains, you can say ‘myonuclear addition’. Sounds impressive, right?

If you were to summarise all of this quickly: the more myonuclei a muscle cell has, the greater its potential for growth. Simple.

Laying dormant despite atrophy

If you stop training, your muscles eventually get smaller. This is called atrophy. After a few months, they could reduce to an untrained size. 

Despite the decrease in size, research suggests that the vast majority of myonuclei you built up during your training phase remain within the muscle. This is even without long periods of not training. In other words, even if the muscle shrinks after months of inactivity, the myonuclei tend to stick around. Think of it like closed factories waiting to be reopened. 

But when you start training, they start working. Since they are already there, the muscle cells can skip the process of creating new myonuclei, allowing strength gains and hypertrophy to occur at a much faster rate than the first time. The factories reopen and the gains commence once again.

And as one 2020 study concludes, such ‘myonuclear permanence’ allows the muscle fibre to regrow more efficiently during retraining, a phenomenon referred to as ‘muscle memory’ [2].

Simple explanation:

  • When muscles are trained, they create myonuclei.
  • The more myonuclei a muscle cell has, the greater its potential for growth.
  • Stopping training decreases muscle size and strength, but the myonuclei stay there dormant.
  • When training is resumed, the myonuclei reawaken allowing muscle growth and strength to accelerate. 

Muscle memory and the CNS

As discussed, the main element of muscle memory and muscle growth is to do with myonuclei. However, this traditional sense of muscle memory also has an impact on regrowing and gaining muscle.

This is thought to occur because muscle memory allows the body to recall the muscle movements and patterns associated with a particular skill, making it easier to regain proficiency in that skill.

When a muscle is repeatedly engaged in a specific movement, the CNS creates a memory of that movement. As the movement (e.g. bench press) is trained and performs the same movement over and over, the CNS adapts to the movement by creating new neural pathways. 

When the person returns to weightlifting, their muscles will be able to grow back more quickly because the neural pathways that were formed during the initial training period will still be present, allowing for improved muscle activation and coordination. This adaptation allows the muscle to perform the movement more efficiently.

Simple explanation:

  • Muscle memory has two parts to it: CNS and myonuclei.
  • Neural adaptations that occur in the Central Nervous System (CNS) allow for improved muscle activation and coordination. This means you complete better quality reps with more muscle stimulation.
  • Trained muscles have increased the number of myonuclei, enabling returning gym-goers to regain their muscle strength more quickly.

 

Do myonuclei stay around forever?

Although they stick around for a while, myonuclei are eventually lost over time if the muscle is not used.

The rate at which myonuclei are lost can vary depending on the individual and the length of time since the last training session. Studies are unclear on how long, but it is likely to depend on genetics, general day-to-day muscle use and protein consumption. It could be that years go by before they disappear completely. 

How long does it take to rebuild lost muscle?

‘Half-the-time’ rule

The ‘half-the-time’ rule refers to the idea that it takes half the time to relearn a skill that has been previously learned and then forgotten, compared to the initial time it took to learn the skill. 

So, for example, if your time off was six months, it could take only two to three months to regain the strength and size you lost. If you had three months off, it would take about 6 weeks. 

This rule only works on a scale of months, not years, so the rule breaks down if your time off was longer than six months or so. After that, it is very difficult to say, and will all depend on factors such as age, fitness level and the specific skill being learned.

The digging analogy

Think of it like learning how to dig. You may once have learned how to dig holes really well, but then stop doing it for a while. Over that period of time, that hole may have filled back up. However, when you return, your skill at digging has not diminished, so you’re able to dig holes more efficiently. Also, the ground is softer, so you’re able to get to the depth faster than when you first dug the hole. 

Summary

Muscle memory is the ability of the body to perform a previously learned movement more efficiently, due to neural and muscle adaptations. When a person performs an exercise repeatedly, their brain and muscles learn and adapt, allowing them to regain strength and skill more quickly when they return to that activity.

The main takeaways:

  • Muscle memory is real – it’s easier to regain muscle loss from a break.
  • If you take a few weeks or months off the gym, don’t stress too much. You can get them back.

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