by Josh Hodnik
The human body is an extremely complex machine consisting of many different systems that work simultaneously with one another to perform a number of different functions. The most complex of these is the central nervous system (CNS). The CNS is part brain and part spinal cord. Without a properly functioning CNS, you wouldn’t be able to walk or talk, and you surely wouldn’t be able to un-rack a loaded bar to perform a set of squats. The central nervous system influences the activity of all parts of the body, and when it’s not functioning properly, strength, speed, and coordination can be impaired. Just like the muscular system, the CNS can be over trained, leading to system impairment. This can result in you feeling tired, weak, and simply unmotivated in the gym.
CNS overtraining usually occurs due to an imbalance between training and recovery. Muscular overtraining occurs when muscles aren’t given enough time to repair broken down tissue. Muscular overtraining normally impacts a certain group specifically. Central nervous system overtraining differs, as it is a systemic issue. The CNS is responsible for generating all muscular contractions, so when CNS overtraining sets in, every muscle group is affected.
Cause of CNS Overtraining
Central nervous system fatigue is brought on by various stressors on neurotransmitters and hormones like dopamine, serotonin, epinephrine, and cortisol in the brain. Intense training, lack of sleep, and stimulant usage are common contributors to CNS fatigue. Micro-trauma occurs during intense training sessions, causing your body to release inflammatory cytokines in response to the muscle damage. The cytokines travel throughout the body and dock on receptors in the CNS, negatively affecting neural recovery.
Certain types of training, when done long-term without de-loading periods, can lead to central nervous system fatigue and overtraining. This can greatly affect strength, and progress in the gym and will ultimately come to a screeching halt. Training that could generally be considered CNS draining activities would be the following:
*Strength work that is performed above 80% of 1RM for lower body and whole-body movements such as deadlifts, squats, etc.
* Maximum effort speed work.
* Maximum effort plyometric work.
* Maximum effort conditioning work.
* Lower body hypertrophy work (8-12 reps to failure).
Sleep, or lack of, is a large contributor to CNS overtraining. Sleep is the body’s prime tool for repair. Failing to get at least 8 hours of sleep each night can limit the body’s ability to recover properly, which will hinder future workouts and competitions.
The use of stimulants can take a toll on the central nervous system, especially when used while training in a way that already induces CNS fatigue. Most preworkout supplements today are packed with stimulants. Many athletes have come to rely on these ingredients to get through long and tiring training sessions. While this may help to increase productivity for some individuals, there is a downside. If you are relying on preworkout stimulants to train effectively, chances are you are already experiencing some sort of CNS overtraining. Stimulants, when taken in high amounts on a regular basis, send the CNS into overdrive. Add this to high intensity training, and lack of adequate sleep like many do, and you have a perfect recipe for CNS overtraining.
Experiencing CNS fatigue is almost unavoidable when maximum efforts are put forth when training. The key is to allow the body to recover from this fatigue, so it doesn’t lead to full blown CNS overtraining. A simple solution to avoid central nervous system overtraining and to allow for strength and muscle gains to be made is to implement periodic deloading or less intense periods in your routine, get 7-9 hours of sleep each night, and keep stimulant use to a minimum.