Burpee and back squat @ 65% of 1RM
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Burpee and deadlift @ 65% of 1RM
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CROSSFIT AND YOUR CENTRAL NERVOUS SYSTEM
Yesterday, many of you experienced a spicy workout of running, double unders and toes to bar. The first half of the workout went well for most, but when the second half of the workout came around quite a few athletes fell apart on the double unders; athletes who could normally string together 20+ in a row could barely string together 2 which led to extreme frustration and the look of “fix me” came on their faces. I just want to take a second and tell you 2 things: First, don’t think that your double unders are going to heck in a hand basket. Second, what you were likely experiencing was CNS fatigue (fatiguing of the Central Nervous System). The following article does a great job explaining the roll the CNS plays in your movement and what happens when it gets taxed. You can see the full article here.
Nervous System Part 1 – CrossFit South Bay
Every time you voluntarily move your body, there are 3 pieces involved, your cognitive brain deciding to move, your nervous system telling your muscles to move, and finally, your muscles contracting to move your body through space. Thus, in CrossFit, we train all three. However, we often focus on the brain (motivation) and the result (muscle contraction), but miss the middle. There always seems to be allusions to the central nervous system in conversations at the gym and in our posts, but we never seem to do a good job explaining why this system is so important to our training… well, that is about to change.
Your nervous system is a very important (and complicated) piece of your body necessary to lifting heavy weights, running fast, or jumping high. Sean did a great job from the anatomy and physiological side giving an intro on how your nervous system works and gets stronger here, but for our purposes today, we aren’t going to delve into the science too much: we are going to focus on how your nervous system affects you getting better. In addition, CrossFit is very, very good at challenging and improving your nervous system, so it is critical that we look at how the nervous system works and affects our bodies.
In plain language, your nervous system is what tells your muscles to fire, how much of your muscle to use and how fast the muscle should contract. By challenging your nervous system (through jumping high, running fast, lifting heavy, etc), you fatigue it similarly as to how you fatigue a muscle. Additionally, the closer you come to going 100% of what you are capable of (whether a box jump height, back squat weight, or all-out sprint pace), the more that your nervous system is stressed as opposed to your muscles. The difference is that as your muscle recovers, you feel sore, and as your nervous system recovers, you feel sluggish. And similarly to training muscles, as your nervous system gets more training, it becomes better at firing your muscles, resulting in jumping higher, running faster, and lifting heavier. I haven’t lost anyone yet, right??
Alright, so, when your nervous system is fatigued, it becomes harder to coordinate and fire all your muscles as you normally would. For example:
- Have you ever had a day when even the bar bar felt really heavy?? Maybe you weren’t even sore, but for some reason, just picking up the barbell felt like 80 lbs??
- Or, you were able to deadlift 200 lbs easily last month, yet 180 lbs feels impossible this week??
- Or maybe, handstands are easy for you, but you can’t seem to hold one after a hard workout.
These are all examples of your nervous system being fatigued. Often, failing a rep has nothing to do with your muscles not being able to support the load, it is your nervous system that is struggling to continue telling your muscle to contract fast enough. Acute (read short-term) nervous system fatigue is why you cannot lift your 1 Rep Max (1RM) more than one time. Depending on the training age of the trainee, to fully recover and pull another true 1RM could take a day, a week, or a month to achieve, as their nervous system would not be capable of achieving the same amount of force more than once without a significant amount of time for their body to rest. On the other hand, chronic nervous system fatigue can occur when your training consists of a many high intensity efforts (read CrossFit). The recovery time from either version of nervous system fatigue will be increased when your sleep, nutrition, stress levels, etc are poorly managed.
I hope this article helps you better understand that sometimes when things aren’t going as planned, it may not be because of your fitness level but your nervous system.