When it comes to exercise, you often hear the saying, "Mind over matter." We believe that through mental toughness and inexplicit grit, our minds can overpower our bodies, leading us through the most challenging workouts.
But what happens when our minds overpower our bodies in order to stop a workout, rather than power through it? This is a simplified explanation of CNS fatigue (central nervous system fatigue), a complication caused by exacerbated overtraining.
To understand CNS fatigue, imagine the following scenario:
You hit the weight room, determined to break through the plateau you felt for weeks. But just two sets in at the squat rack, you find yourself unable to complete another rep.
The pattern remains throughout the entirety of your workout: Weights that were once a warm-up set are now a struggle, even though logic tells you that you should be stronger. After all, you hit the gym every single day, so you should continuously see progress, right?
Wrong.
The burnout you feel in your workouts could be a clear indicator of a much larger problem. Going too long without rest can easily lead to overtraining, which — if not addressed — can give way to CNS fatigue. Central nervous system fatigue is caused when your brain stops telling your muscles it's time to do work, causing a serious detriment to your workout.
Below, I explain what CNS fatigue is, what causes it, and the secret to overcoming CNS fatigue in your workout routine.
A Recap of the Central Nervous System
In order to understand central nervous system fatigue, you first need to understand the central nervous system itself.
The central nervous system is made up of your brain and your spinal cord. Together, your CNS helps interpret your surroundings, think thoughts and feel feelings, experience all five senses, and perform regular motion functions such as walking, swimming, biking, performing a deadlift, or crushing a HIIT workout.
There's a part of your brain called the motor cortex, which allows it to control physical movements. Located in your frontal lobe, the motor cortex is what allows your skeletal muscles to perform precise movements. In other words, the motor cortex is what tells your body which movements to perform when you row a dumbbell, swing a kettlebell, or jerk a barbell above your head.
What Is CNS Fatigue?
CNS fatigue is a defense mechanism. It's your mind's way of saying, "You are exhausted, and up until this point you have refused to do anything about being exhausted. Therefore, I'm purposely shutting down your body so you'll be forced to rest."
Which is exactly what happens.
With the onset of CNS fatigue, you will lose the ability and/or efficiency of engaging certain muscles. While your training logs and exercise history state that you should be perfectly capable of completing a given movement, CNS fatigue prevents you from doing so.
While research on CNS fatigue is heavily debated (more on this below), most scientists and fitness professionals believe it's caused by overtraining, poor nutrition, or lack of sleep. When intense, prolonged exercise occurs too frequently — without adequate rest in between — your mind eventually forces your body to shut down.
Is CNS Fatigue the Same as Overtraining?
No, they're not the same. Think of overtraining as the step that comes before the onset of CNS fatigue. When you overtrain, you can typically take 1-3 days off and bounce back in your workouts. Or, you can book yourself a massage, try cryotherapy, or swap out a HIIT workout for active recovery and feel like yourself again.
CNS fatigue runs far deeper than a bout of overtraining. CNS fatigue is chronic muscle fatigue caused when your brain tries to prevent certain movements — from strength training to simple, daily tasks. It can also stall muscle growth, which explains your sudden plateau at the gym.
The Difference Between Peripheral Fatigue and CNS Fatigue
When we think of fatigue caused by high-intensity exercise, we typically think of peripheral fatigue. Peripheral fatigue, or regular muscular fatigue, is caused by a buildup of lactic acid in the muscles, which can cause pain and soreness after an intense training session.
When you think of overtraining, you are thinking of physical exhaustion related to peripheral fatigue. This can easily be resolved through a number of proven recovery methods, including foam rolling, dry needling, stretching, and massage.
CNS fatigue, on the other hand, is much more serious and much more long term. A quick Netflix session on the couch or a trip to a masseuse won’t fix CNS fatigue (like it would peripheral fatigue). Think of it this way: While you might get sore from one workout (peripheral fatigue), one workout won’t lead to a CNS fatigue. Instead, it’s caused by a chronic, long-term buildup of doing more than your body can handle, until your body physically shuts itself down.
And since it took more than one workout to get to that point, it will take you far more than one rest day to get yourself out of it. To truly rid yourself of CNS fatigue, you need to make serious, long-term changes to your wellness and recovery routine.
If you are an avid gym goer, you may be familiar with a condition where after a very hard workout especially involving compound movements like deadlifts, you may get dizzy or even have a blackout. This is short-term, acute, and caused by very high levels of stress for your CNS. However, this falls into the category of peripheral fatigue. You normally recover from this very quickly (within minutes). This condition is not CNS fatigue because that’s chronic and much more long term.
What Causes CNS Fatigue?
Again, research is still growing on the exact cause of CNS fatigue. However, research shows that motor neurons may offer some sort of explanation.
The Role of Motor Neurons
Motor neurons in your spinal cord connect to your muscles, glands, and organs throughout the body. These neurons transmit messages from your spinal cord to your muscles in order to conduct any movement (such as cardio or resistance training).
However, when you work out too hard, too often, these motor neurons become tired. As your neurons become fatigued, they can't fire rapid messages from your brain to your muscles. Therefore, you can't perform the same explosive, intense movements as you once did.
The Role of Neurotransmitters
It is believed that two neurotransmitters — dopamine and serotonin — play a role in the development of CNS fatigue.
Typically, heightened levels of dopamine are associated with boosted mood and energy levels, while higher serotonin levels are often met with feelings of lethargy, drowsiness, or depression. Individuals who suffer from CNS fatigue are often found to have lower levels of dopamine and higher levels of serotonin, which slows down muscle contractions, neuron excitability, and ultimately your muscle activation.
While we're not sure exactly how this happens, we do know that dopamine levels are typically lower after prolonged exercise. If you follow a rigorous training program that doesn't incorporate rest days, your dopamine levels can become chronically low, which could therefore lead to CNS fatigue.
How Do You Overcome CNS Fatigue?
The best way to combat CNS fatigue is to take a day off (and then another).
You need to rest if you want your brain and body to start working together again (rather than against each other). But as stated earlier, it might take more than a day off to combat CNS fatigue. Instead, you may need to examine how you eat, sleep, and train. Here are a few pointers to help you get started:
1. Perform Different Types of Exercise
Some wellness professionals believe CNS fatigue can worsen when we perform the same types of workouts each day. This is especially prevalent amongst powerlifters or bodybuilders, who perform repetitive exercises for the sake of competition.
To prevent this from happening, follow a well-balanced fitness program that encompasses a wide range of exercises. This is why the Build Bullet-Proof Health program incorporates both strength training and cardio movements to keep your body balanced.
2. Rethink Your Sleep Patterns
If you want to combat CNS fatigue, you need to take a serious look at your sleep patterns.
Simply getting the recommended 7-8 hours of sleep per night may not be enough. Instead, look at the quality of sleep you're getting — are you waking up in the middle of the night? Are you using electronics before bed? Is your bedroom filled with unnecessary light and/or noise? Aiming for good sleep hygiene could lessen your CNS fatigue and boost your exercise performance.
3. Ensure You Consume Proper Nutrition
A poor diet has a number of negative implications. It can slow muscle repair, cause feelings of lethargy and depression, and put you at risk of a number of metabolic disorders.
If you believe you're suffering from CNS fatigue, ensure you are consuming enough amino acids (the building blocks of protein) to repair muscle damage post-exercise. To ensure the health and repair of your muscle fibers, you may need to consider supplementation. Consuming a high-quality protein source — like grass-fed whey protein — after your workouts will help induce muscle protein synthesis, helping to repair, grow, and build muscle groups broken down during exercise.
In addition, some research believes that CNS fatigue could be due to a lack of carbohydrates. If you are following a low-carb diet, like the keto diet, you may want to increase your carb intake to see if it benefits your neuromuscular functions.
4. Implement Regular Rest Days
If you work out at a high-intensity level, completing HIIT workouts, powerlifting, or wind sprints throughout the week, then you need to implement adequate rest.
Adequate recovery is one of the most vital yet often overlooked areas in fitness. All too often, whenever athletes hit a plateau their only course of action is to work out harder — working out twice a day, weightlifting with heavier weights, or completing longer runs. However, sometimes the only way to break through a plateau (and combat CNS fatigue) is to take a day off.
While I encourage you to make the most of your rest days, practicing foam rolling, ART (active release therapy), and the best type of stretching, I also encourage you to lay on the couch. Remember, CNS fatigue runs deeper than typical muscular fatigue. In order to get back to the gym, you will have to rest far longer than you believe.
5. Address Stress in Your Daily Life
When you work out, your body releases cortisol — the stress hormone. In small doses, cortisol can be a good thing, helping us lift heavy weights, run faster sprints, or rise to meet any number of challenges.
However, if you workout too long or too hard, your chronically high cortisol levels tell your body that it’s under attack. Therefore, your body will do everything it can to protect itself, hoarding food, slowing down your metabolism, and potentially entering a period of CNS fatigue.
Taking a rest day can address the cortisol released during exercise, but it won't address the stress caused by your daily life. An unfulfilling job, toxic relationships, long commutes, and other lifestyle factors can inadvertently tell your body that it's under attack. If you truly want to combat CNS fatigue and feel better, you will need to reduce the stress caused by work and life — not just exercise.
6. Strengthen Your Brain
In order to bounce back from CNS fatigue, you may need to pause your physical workouts and try a mental workout instead.
Take part in a yoga class, try meditation, or make regular walks (enjoy nature without headphones) part of your daily routine. Research shows that meditation can benefit motor memory and motor task performance, which can help combat CNS fatigue. In addition, meditation, yoga, and similar activities have been shown to reduce stress levels and boost dopamine levels, which improve the health of your central nervous system.
7. As Always, Listen To Your Body
As stated earlier, CNS fatigue is not the same as overtraining. CNS fatigue sets in when overtraining is not addressed, and muscle fatigue extends for far too long that it negatively impacts your central nervous system.
The truth is, it never has to get to this point. I highly encourage you to take a serious look at your training habits, and notice when you're pushing yourself too far. Are you skipping rest days? Are you working out when you know you're still sore from a previous workout? Do you work out when you're sick, hungry, or exhausted after a poor night's sleep? Do you use exercise as an escape from a demanding job, stressful home life, or unfulfilling relationships?
If you are looking up the symptoms to CNS fatigue online, chances are you already feeling exhausted, lethargic, and beaten down. Take this as a sign: Your body needs a break, and I hereby excuse you from today's workout.
CNS Fatigue Is a Serious Issue in the Fitness Community
Regular muscle fatigue and soreness is a normal part of an active lifestyle. However, when you work out too hard, for far too long, you run the risk of developing central nervous system fatigue.
CNS fatigue is a serious condition where your motor neurons stop firing, so your brain no longer communicates with your body. When this happens, you can't perform workouts or even simple, daily tasks.
To combat and prevent CNS fatigue, you need to make recovery a top priority in your fitness routine. In addition, you need to get adequate nutrients, plenty of sleep, and follow a well-balanced and diversified training program.
I hope this post sets you up for success. It is super important to listen to your body. I created a new program that is designed to optimally prepare for a Spartan race or any other obstacle race. It incorporates ideas for healthy recovery respecting fatigue. You can find more details here.
Thank you loved this read. I was being to think I was just getting lazy.
This was great! I’m experiencing CNS fatigue now. I think droopy eyelids is one of the symptoms. Low grip strength too.
Love this! Thank you for sharing!