CNS Fatigue.......and then RECOVERY

It is a well recognized and often implemented training method, to push yourself to failure, go until you cannot go anymore, and then allow your body to rebuild itself to be stronger than it was before. 

My StrongFast training program is designed around this principle, a planned overload. I want to maximally task my system, with minimal rest. It's the razor's edge balance, running farther and faster, without over-training . There is no recipe for optimal overload and when you are still within your current limits, you cannot tell how close to the edge you are. 

What you do need to be able to tell is if you are over that edge and entering into a state of being over-trained. This was the state that I was in a few weeks ago, after a 10 week period of overloading my system.  My over-training came not in the form of injury, but fatigue of my central nervous system (CNS). In the week and a half leading up to my acknowledgement that I was over-training, my performance during both running and strengthening workouts showed either a plateau or a regression, as well as having a heavy feeling in my legs. More noticeably, I had the symptom of a heightened level of anxiety, which increased before any training session, with the lead up to two of the sessions including a quivering lower lip and teary eyes.

These two symptoms of anxiety and decreased performance are common when experiencing CNS fatigue, a term related to over-training. To simplify, your central nervous system consists of your brain and spinal cord and works to regulate and control not just the movement and performance of your muscles during a workout, but all of the bodily systems (endocrine, cardiovascular, etc) that are working in harmony while exercising.

During a set of squats, for example, your CNS system is producing and sending the message to your muscles to fire and contract with the appropriate amount of force. It is also regulating the level of dilation or constriction of your blood vessels, heart and respiratory rate, hormonal levels and many other factors to facilitate the force production of your muscles. Regularly requiring this system to work at or near its maximum level can lead to fatigue of the system, meaning that it will not be able to efficiently coordinate your body during exercise, resulting in sub-maximal performance despite a maximal effort. In addition to this primary indicator of decreased performance,  sleep disturbances, loss of appetite and change in mood can also be present. 

Having come to the realization that I was in a state of CNS fatigue, the next two weeks were treated as a recovery or de-load period. The aim during this time was to allow for full recovery and adaptation from the previous couple of months of progressive overload, while trying to minimize the loss of training effect. I still completed runs, squats and lifts, but without tracking my pace or trying to break any person bests. The duration of this recovery period was planned as one week, but was extended to two when it was apparent that I was not fully recovered after one week.

It was an interesting experience to feel this new level of fatigue. Because it felt like my brain was foggy, it made it hard to judge how tired I was. This is the risk regarding over-training, when you are in the midst of it, it can be challenging to identify. Quantitatively tracking your performance, as well as tracking fatigue, sleep patterns and mood can help when monitoring yourself. In my case, having a friend act as my better judgement and recommend a light week was very useful.


Likely, the combination of a rested brain and body, following a period of significant running and strength training, led to significant gains in my first week back at full training.

Here are the numbers from the last three weeks' squat workouts as an example (each week the goal is to complete more squat repetitions than the previous week, at 135 lbs).

June 19th – 52 squats completed in 5 sets = total volume of 7020 lbs

June 26th – 53 squats completed in 5 sets = total volume of 7155 lbs

July 3rd – 62 squats completed in 4 sets = 8370 lbs!

That is a 15% increase in performance in one week! It is highly unlikely that my leg strength improved by that amount in a week, but it is undeniable that my body’s ability to perform improved significantly in a relatively short amount of time.

There are two points to take from this. Firstly, if you want to get stronger and faster, whatever your sport, you need to push yourself to what you perceive as being beyond your current abilities. Secondly, it is important allow your body to recovery after prolonged overload.

And then do it all over again! and again! and again!