Pretty much every lifter knows about the dangers of overtraining. If not prevented, overtraining can wreck your gym gains and derail your progress.
However, are you as cognizant of CNS fatigue? Did you know that just like your body can by physically overtrained, your nervous system can be overtrained as well? Below is a quick primer on CNS fatigue, as well as how you can reduce the risk of it happening.
What Is CNS Fatigue?
Your brain sends signals via your central nervous system to your muscles in order for them to contract. So in order to curl that barbell, your brain sends a signal to you biceps via your CNS to contract the biceps, curling your forearm up to your upper arm. The harder and/or faster the contraction has to be, the stronger the signal has to be.
Well, since your CNS has to transport these signals, it can get worn out. And the stronger the signals are, the more wear and tear it takes on the CNS. Think of your CNS as a highway. If people drive smart and safely, it can generally stay in good shape for years. If people drive crazy, then the highway can fall into disrepair. This is sort of what happens with your CNS.
The problem with CNS fatigue vs physical overtraining is that you don’t feel it coming on. With overtraining, you feel sore all the time, lethargic, may experience minor depression, etc. But when your CNS is drained, you don’t really know it until your lifting/performance simply just goes down the drain. And by then, it’s too late.
When Does CNS Fatigue Happen?
CNS fatigue happens when you train too intensely for too long. Now, you have to realize that in this case, “training intensity” doesn’t necessarily equate to how much effort you’re putting into the gym. Rather, it refers to the exercise science definition of intensity, which is training at your maximal level.
In other words, the closer you’re training in relation to your max performance, the more “intense” it is. This would mean because a 300lbs squat is heavier than a 200lbs squat (and therefore, closer to your max), it’s more intense. If the highest box you can jump onto is 32”, a 28” box jump is more intense than a 24” box jump. And if the fastest you can run a mile is in 7:30, a 8:15 mile would be more intense than a 9:30 mile.
How to Fend Off CNS Fatigue
The easiest way to fend off CNS fatigue is to keep your training intensity in check. This doesn’t mean you can’t train maximally or never go all out. It just means you have to be smart about it and not do it all the time. One way of doing this would be to use long term linear periodization. If your training cycle lasts 10-12 weeks, and the most intense portion of it is the last 2-3 weeks, this means most of your program will be spent in a lower intensity range that should be safe.
Deload weeks could be another option. Every 4-6 weeks, reduce your weight and/or total training volume by 50% or so. This will take a load off the CNS and give it time to rest, recover, and even “reset” from the intense training you’ve been doing.
Lastly, you could just always stay within a lower overall intensity range. CNS fatigue really only starts to become an issue if you’re training at 90% or above. Keeping all your training in the 65-85% range would pretty much guarantee your nervous system wouldn’t get burned out.
The great thing about this range is that while it’s much easier on your CNS, it’s still intense enough to make good progress. It allows you to train heavy enough to get stronger, with enough volume to build muscle mass, fast enough to improve your speed/power, and with enough cardio to benefit your conditioning.
CNS fatigue is the last thing you want to experience. You won’t realize it’s happening until it’s too late and it can completely disrupt your training progress. However, if you implement any of the above, you should be able to ensure your nervous system stays in prime working order and that gym progress can keep coming.