'Central Fatigue' May Be Stunting Your Progress

If you think you’re failing to achieve fitness gains due to a lack of effort or training volume, it could very well be the exact opposite case. We get so caught up in what our muscles are doing (or failing to do), that we often forget about the main driver of our physical activity — the central nervous system.

The CNS governs homeostasis in our bodies, integrates and processes all incoming sensory information, and directs every muscle movement. If you play your cards right, you can utilize its abilities to recruit maximal muscle fibers and achieve consistent hypertrophy.

Unfortunately, there are a few common mistakes gym-goers make to stunt this relationship between the nervous system and the muscles. Don’t fret, however, as it doesn’t take much to swing the pendulum in the right direction. It all starts by understanding what’s really going on in that complex nervous system of ours.

Here’s a quick breakdown of what ‘central fatigue’ is, and why you should pay more attention to your rest and recovery periods to maximize progress.

Want more rest and better results? Just do this!

Working Hard or Hardly Working?

During vigorous lifting exercises, we can often experience ‘failure’, or the inability to complete another repetition. What we attribute this sensation to is most likely peripheral fatigue. This is the idea that your inability to continue the exercise, and achieve further muscle growth, is stunted by the ‘exhausted’ muscle fibers that are involved in the action. In a physiological lens, this means that your energy stores are depleted, and there is an accumulation of by-products and impairment of muscle contractility. In layman’s terms, you work hard and your muscles fatigue, which in turn leads to a reduction of skeletal muscle function.

While this may very well be the case in a weight-lifting scenario, there’s often more to it than meets the eye. Research shows that this ‘localized failure’ is just a piece of the puzzle. Changes in performance concerning peripheral fatigue have been carefully investigated in humans in response to different types of exercise, and researchers have documented a secondary (extremely influential) source of fatigue. This is where the central nervous system comes in.

Limitations to strength are both muscular and neurological in nature.

The simple definition of central fatigue is the inability to maximally recruit a muscle. According to The Muscle Ph.D., this is rooted in a decreased input to motor neurons, increased afferent inhibitory feedback, and reduced responsiveness of individual motor neurons. Fancy physiological terms aside, just know that when this type of fatigue emerges, it's much harder to achieve muscle growth because you’re not lifting to your maximal capacity.

The reality is, when you’re scrambling to squeeze in one more set to failure or feel like you’re burning out due to ‘sore’ or ‘tired’ muscles, the nervous system may just be tired. It sounds a little funny, but research proves that your fatigue is far more complex than physical exertion or mental weakness...you might be (quite literally) ‘getting on your own nerves’.

The question now becomes, what can we do to avoid this state? How do we train in a way that maximizes gains while minimizing wasted time?

How to Avoid Central Fatigue to Maximize Muscle Growth (5 Tips)

Now we may not be able to fully circumvent central fatigue, but there are several tactics we can utilize to give ourselves the best shot at sustainable muscle growth. Please read and apply each one with a grain of salt as this is a relatively new area of research. There are bound to be subtle changes to these strategies as new information rolls in, but for now, this is a great start. Finally, remember that this is referring to maximal lifting. If you're not pushing yourself to the limit in the gym, many of these principles don't apply as heavily.

Without further ado, here are 5 tips for keeping the nervous system on your side while you train. Here’s to new gains!

1) Cardio and strength don’t mix when it comes to maximal lifting.

High-repetition endurance training and heavy cardio sessions may cause more CNS fatigue than traditional hypertrophy or strength training. Try to plan your cardio days separate from your strength work to reduce unnecessary CNS fatigue when you’re lifting heavy.

2) ‘Pushing it’ may be counterintuitive.

Completing more than 1-2 sets to failure will essentially ‘exhaust’ your nervous system. You will likely not have any additional musculoskeletal benefits from trying to push through further sets. Don’t waste your time and energy!

3) Rest for longer than you think.

CNS fatigue lasts for at least several minutes after each set of strength training and accumulates over a workout. If your goal is hypertrophy or strength, short rest periods are less effective than long ones. This will be different for everyone (and each specific exercise regime), but I’d recommend taking at least 5 minutes between heavier sets. This may not be a realistic ask for you busy folks, but it’s just the nature of the beast.

4) Order is important!

Since CNS fatigue can build up during a workout, place your most important exercises at the beginning of the workout and your least important ones towards the end. This way you’ll be sure to maximize your body’s response to the movements you’re prioritizing for that session.

5) Recovery is key. Do it well.

The CNS recovery period is similar to that of muscle soreness (48–72 hours). Ensure you’re practicing good recovery habits, such as proper sleep hygiene, nutrition, and stress management. This can go a long way to sustainable growth and improvement over the long term.

Utilized resources: Central and Peripheral Fatigue During Resistance Exercise — A Critical Review, CNS Fatigue, Why does central nervous system (CNS) fatigue happen during strength training?

In Closing,

If you’re experiencing a plateau in the gym, it may have nothing to do with your effort or training volume. As a fitness community, we’ve overlooked the importance of the nervous system’s role in maximal muscle fiber recruitment and hypertrophy. Fortunately, we can use recent research to modify our workouts and get back to training productively.

Nobody wants to be sweating in the gym for no reason. As much as we need to be lifting heavy and often to achieve gains, we must also know when to rest and recover. Optimized training requires a full understanding of how the nervous system responds to certain stimuli. Now that we’re more aware of the complexity of this exercise-induced fatigue, we can begin to design programs that maximize efficient growth and proper recovery.

By implementing the five strategies above, you will start to see the progress you thought you should’ve been making from the start. The best part is you won’t be putting in any extra effort to get there!

Train smarter, not harder.