Does Muscle Memory Occur?

The concept of muscle memory is controversial. Most bodybuilders have experienced this phenomenon, yet virtually no discussions of this topic have appeared in scientific and athletic publications. Although there is some speculation herein, these ideas are sure to help you better understand your body’s response to training after a layoff.

Before you know it, a month has gone by. Two months. Six months. I’ll get back to it sometime soon, you keep saying. You’re finally ready – a year later.

Don’t worry. Life can get in the way of even the most dedicated bodybuilder’s workouts. Be glad that you’re ready to commit to consistent training again. For those of you who haven’t attempted a small comeback before, here’s good news.

Gaining muscle size seems to be easier the second time around – even if you starting from the same place. That’s right. It appears that your muscles can reach their former size (their size when you stopped working out) in a much shorter time than it took to achieve that size that first time you trained.

If you’re an experienced bodybuilder who has returned to square one more times than you wish to remember, you probably know exactly what I mean. In fact, even many scientists and coaches are convinced this phenomenon occurs – having witnessed first hand. No one has a clue how this happens. Why should you pack on muscle size quicker when ‘retraining?’ It just doesn’t make sense.

With so many athletes and others observing this mystery of the iron game, some plausible explanation must exist. I’ll describe some possible reasons why your muscle may appear to have a memory. While understanding that the following ideas might help you make a comeback, keep in mind that these are just good guesses – not dogma.

Mind Games

Certainly, we can’t overlook the possibility that muscle memory doesn’t really occur at all. In other words, it’s completely possible that these changes have nothing to do with muscular adaptation. Then why do muscles seem to progress faster during a comeback? Well, it could all be in your head. Here’s what I mean.

The first time you trained consistently, you were probably a bit hesitant with the weights. You weren’t too sure how your muscles would respond and most importantly, you didn’t have a good idea how much weight you could lift. So you were cautious when it came to big weight increases – at least until you felt you could handle the heavier weight safely.

When making a comeback, that initial fear is gone. You know you can handle heavier and heavier weights because you’ve done it before. You probably expect to attain your former strength soon, anyway. For these reasons, you are more likely to add weight to the bar at a faster rate – pushing yourself as never before. Of course, this progressive overload will lead to quicker gains in strength and size.

The Nerve of those Muscle Cells

Perhaps the most likely explanation of muscle memory involves the neurons (nerve cells) that stimulate your muscles. These neurons tell all the muscle fibers (muscle cells) they innervate to contract. But, depending on the amount of weight being lifted, only a small percentage of neurons innervating a particular muscle may be recruited to stimulate their fibers. More weight on the bar – more neurons involved and more fibers stimulated. Simple enough, right?

Here’s something really interesting. Even during maximal voluntary contraction (attempting your max on any lift), you’re still not recruiting all the muscle fibers in your working muscles. In fact, it is this discrepancy between the percentage of fibers we normally recruit and what we theoretically can recruit (100%) that may account for those rare, but documented feats of superhuman strength.

What has that got to do with muscle memory? Well, one way your muscles may adapt to the stresses of consistent training is to increase over the long run the total percentage of fibers recruited during maximal and near-maximal lifts. Here’s the possible scenario:

The first time you trained, you recruited a certain percentage of muscle fibers during maximal lifts. As you trained more and more, this percentage increased. Then you stopped working out. When making a comeback, this ability to recruit a greater percentage of muscle fibers remains intact. Therefore, you’re starting with a capacity to develop more force within a muscle (since more fibers can be activated). Compared to the first time you trained, you’re one step ahead.

If you can develop more maximal force, then you can lift more weight – you’re a bit stronger. Although you may think you’re starting from the same place, this greater strength will enable you to progress faster, resulting in an ability to regain muscle size at a quicker pace.

The second way that neurons may be involved in muscle memory deals with skill development. When you start working out, your muscles interpret most of the lifts as new movements. So your neurons must develop the appropriate pattern of stimulation to get the weight up. Remember how shaky the bar was the first time you tried the bench press?

Fibers must be activated in just the right sequence to perform complex movements like the bench or the squat. And learning a new skill (just like trying to swing a golf club, etc.) may take quite a long time. The first time around, it may have taken you weeks to feel steady on the bench. Now those neural patterns have been developed and though they may be rusty, they can return very quickly after a layoff. What may be happening here is that after you stop working out you lose some of those neural patterns. When you work out again the neurological changes come faster. This accelerated restoration of neurological control will enable you to stimulate your muscles more efficiently, eventually causing the leveling off you reach in muscle strength and hypertrophy to be higher. You may be stronger and bigger when the neural patterning is done the second time around.

Muscular Adaptations

Another possible explanation of muscle memory concerns certain changes in your muscles that regular training may produce. Your muscles may adapt in two ways that could translate into faster gains during retraining. First, you may be able to increase the capillary bed surrounding muscle cells, creating a greater blood supply to the working muscle. If this happens, and many scientists believe it does, you would then be able to enhance the nutrient (glucose, branch-chain amino acids, etc.) availability to the muscle cell. Also, you might remove the waste products of repeated muscular work and energy production (lactic acid, heat hydrogen ions, etc.) at a faster rate. Since these waste products can limit performance, with the increased capillary bed, you would be in a position to train harder and longer.

Either or both of these situations would probably enable you to create a more effective muscular stimulus. This is the key in terms of muscle memory. These positive changes from an enhanced blood supply would be restored soon after a comeback since the capillary beds would quickly reopen. Thus you would have the advantage of a greater muscular stimulus from the start of retraining. This would lead to a greater adaptation – stronger and bigger muscles – and give the illusion of muscle memory.

Second, the enzymes that are involved in important bio-chemical reactions may be responsible for muscle memory. For example, we know that enzymes in reactions leading to the storage of glycogen (your energy source during anaerobic work) can be enhanced with training. It is plausible that enzymes involved in protein synthesis may increase in concentration and activity following repeated muscular stimuli and damage. It may actually be those enzymes that have a memory, quickly returning to their former increased concentrations and turning on these processes earlier. If this occurred, you’d be able to work out harder, possibly recover faster, and gained muscle mass more quickly than when you first trained.