You haven’t ridden a bicycle in years. Yet despite your lack of recent pedaling experience, you’re still able to hop on a bike and go for a spin. Ever wondered why? It all has to do with “muscle memory.” Despite the name, muscle memory really has more to do with brain pathways than it does muscle fibers. Here’s why muscle memory is such a powerful force when it comes to riding a bike or maintaining a toned physique.
Muscle Memory and Your Brain
When you learn a new skill, like riding a bike or snow skiing, it’s not smooth sailing at first. You take a few tumbles until your muscles, tendons, and joints get “in sync” with your brain. Each time you climb on that bike and struggle to pedal while trying to stay upright, your brain sends messages to your muscles and tendons telling them to fire up. At the same time, proprioreceptors around muscles and tendons send feedback back to your brain about their movements and position in space. Information from these proprioreceptors helps you make the adjustments you need to eventually ride without taking a tumble. Over time, pathways are established between your brain and the muscles you’re using to balance on that bike, similar to the way walking over and over on the same spot creates a trail. Your brain and muscles can use this pathway or “trail” every time you climb on a bike to go for a ride. Even better, that pathway remains intact for years and decades even when you don’t set foot on a bike. That’s the concept of muscle memory at work.
Muscle Memory Exists for Strength-Training Too
Muscle memory doesn’t just hold true for riding a bike, it also applies to strength-training. If you’ve ever taken a long break from weight-training, you probably found it was easier to recoup your strength and muscle tone the second time around. That’s because your brain and muscles established pathways called neural pathways the first time you trained. Those neural pathways were reinforced repeatedly through repetitive training, forming a pathway your brain and muscles could quickly reestablish once you started training again. Muscles may not have gray matter, but they certainly can remember.
There’s even evidence that strength-training changes muscles structurally and that these changes persist even when you take a long break from training. When researchers in Oslo put mice through a strength-training routine and then had them rest for a long period of time, they lost muscle mass but retained muscle nuclei. This is important since muscle nuclei contain the DNA that codes for new muscle tissue. At least in mice, new muscle nuclei formed through strength-training persist for indefinite periods of time, making it easier to regain lost muscle.
This seems to apply to humans too. Researchers at Ohio University put healthy, young women through a strength-training program for four months. At the end of the four months, the women spent the remainder of the year taking it easy. Even though the women didn’t strength train during this time, they still had the majority of the muscle fibers they built eight months earlier. Once they got back to the gym, they developed strength and lean body mass more quickly than first-time trainees. The take-home message? Once you’ve established those important neural pathways from the brain to muscle, regaining muscle and strength is easier.
It’s Easier the Second Time Around
Working hard to develop those pathways will work in your favor if you ever have to take time away from the gym. You may lose muscle mass and strength, but the pathways to redevelop that strength, and, possibly, the muscle nuclei are still there just waiting for a little stimulation.
How long do these neural pathways remain intact? At least when it comes to skills like riding a bike, the pathways exist for decades. It’s not clear whether the same holds true for strength-training. Whether it’s possible to stay away from the gym for 20 years and still get your strength back quickly is unknown. How long the neural pathways stay intact may depend on how well-established they were in the first place. If you spent many years strength-training, that should work in your favor if you need to take a long break. On the other hand, if you only lifted for a few months, the pathways may not be so ingrained, and you’ll have to work harder to recoup your strength and mass. Age may be a factor too. If you start training at an earlier age when neural pathways are more easily built, you may sustain strength-training advantages longer than if you start training when you’re 40.
The Neuromuscular Adaptation Phase
Getting stronger and getting toned muscles is not just about developing bigger muscles by lifting heavier weights, but also increasing neural pathways from your brain to your muscles. In fact, until you thoroughly develop neural pathways to a muscle it is very difficult to increase the size of that muscle or to even get the maximum benefit of your training effort.
It can take six weeks or more to see changes in your muscle. On the other hand, strength gains happen more quickly. Despite the fact that your muscles don’t increase in size during the first few weeks of strength training, they do become stronger. This is due to changes in the way your brain interacts with your muscles fibers by developing more neural pathways to them.
Muscle fibers are grouped into motor units. Each motor unit is a cluster of muscle fibers innervated by a motor nerve cell. During the first weeks of strength training, your brain responds to training by recruiting more motor units with each muscles contraction. This means you have more muscle fibers working in your favor to move a weight. This increases the force you can generate.
Even though you haven’t increased the cross-sectional area of the muscle yet, your brain gives you an extra strength boost by recruiting more motor units to allow you to generate more force. It also increases how rapidly these motor units fire. This is called neuromuscular adaptation.
After 4 to 6 weeks of training, if you’ve challenged the muscles sufficiently, your muscle fibers will start to increase in size. This further boosts muscle strength as the muscle cross-sectional area enlarges or “hypertrophies.” This is when you start to see the first signs of muscle enlargement and the much hoped for ripples when you flex your biceps.
Over time these neural pathways will allow you to contract even more muscle fibers and will allow you to more thoroughly develop your muscles.
What Does This Mean?
This should come as some reassurance. If you ever sustain an injury that keeps you from lifting a weight or pulling a resistance band, all is not lost. Those neural pathways you worked so hard to build are still there. You just have to re-stimulate them. The gains in strength and lean mass should be easier the second time around.
As you make progress by sticking to your strength training program, your ability to use multiple motor units increases dramatically. Build a strong foundation now, and you can reap the rewards for years to come – thanks to muscle memory.
References:
NPR. “No More Gym? Don’t Worry, Your Muscles Remember”
PNAS Journal “Myonuclei Acquired by Overload Exercise Precede Hypertrophy and Are Not Lost on Detraining”
Women’s Health Magazine. “The Secret to Being Fit for Life: Muscle Memory”
Related Articles By Cathe:
What Happens When You Stop Lifting Weights?
Muscles Never Forget: New Study Shows Muscle Memory is in Your DNA
The Science of Muscle Memory and How It Works in Your Favor
Muscle Memory: Why It’s Easier to Get Into Shape the Second Time Around
