Nervous System Fatigue: A Q/A with Coach Larry Cain

This is an example of the discussions taking place daily on the Paddle Monster Forums, available to all access and basic members:

QUESTION:

Larry, I am not too familiar with nervous system fatigue and what feels like. I’m sure I have felt it but how is it different than muscle fatigue? Does it come later, after I have paddled?

ANSWER:

As far as the nervous system goes, fatigue is different than muscular fatigue. Consider this:

The nervous system controls all muscle contraction, taking instructions from the brain and directing the muscles to carry them out. So when you make a conscious decision to alter your stroke it is the nervous system that makes it happen. The muscles are just following instructions.

At the same time, there are specialized cells located in muscles that are essentially part of the nervous system and collect information about stretch, load, and tension in the muscles. They transmit this information to the brain so that the brain can interpret it and dictate an appropriate response. So, when your board is bouncing around underneath you in rough water, these cells (called proprioceptors) in your feet and lower legs detect how the board is moving. Your brain then determines the necessary response and sends the instructions back to the muscles in your feet and lower legs so that they can do what’s necessary to maintain your balance. This process happens in similar fashion in muscles throughout your body.

Obviously this transfer of information happens incredibly fast and a ton of information is conveyed and very precise muscular responses result. It’s extremely complex. When the nervous system is functioning normally these pathways operate at peak efficiency and the information transfer is optimal and rapid.

However when the nervous system becomes fatigued this pathway operates less effectively. It’s almost like some of the information doesn’t get though or get through quickly enough. Going back to the board analogy, it’s like some of the information about your balance doesn’t get picked up or get through to your brain. It’s also like what your brain is telling your muscles to do doesn’t seem to result in your muscles responding properly. Hence your ability to balance effectively is affected. When I’ve dealt with excessive nervous system fatigue in the past it’s been like I’ve forgotten how to paddle. I don’t feel the water as well, can’t find appropriate load and sequence the contraction of muscles properly (hence my motion feels out of sync) and I struggle to find power. This struggle to find power occurs because the nervous system is also responsible for recruiting muscle fibers to a physical task like lifting a weight or pulling a stroke. The reality is that most people are only able to recruit a fraction of the available muscle fibers in any task like lifting or paddling. Doing max strength training in the gym or speed training on the water teaches you to innervate and recruit more fibers. It essentially opens up pathways to fibers you wouldn’t normally use and makes it easier to apply and control them in a given task.

Nervous system fatigue is twofold – for lack of better terms consider them “acute” or “chronic”. “Acute” fatigue happens within a short period of time like a workout where your nervous system fatigues and you find it more difficult to control your movement or be powerful at the end of the workout than you did at the beginning or during the middle of it. “Chronic” on the other hand is the result of repeated daily stress on the nervous system with insufficient recovery time. This could theoretically happen from pulling too hard for too many days in a row without sufficient rest or a day off. This is especially likely when training programs intensify and there is more high intensity work with insufficient recovery between. This is why days off are important and balance to the training program is important. It’s also why trying to pull really dynamically everyday can get you in trouble. Sometimes you need to pull a little easier for a day or two or for part of a workout to avoid overloading the system that is trying to make you execute that technically perfect, dynamic stroke.

You commented that you’re going on a snowboarding trip. Well, you’re likely experience some nervous system fatigue when you’re learning to snowboard. For me it went like this the first time I tired it:

  • First hour I was totally spastic and falling all over
  • Then I started to really get the hang of it. This was when my brain was able to start making sense out of the information the proprioceptors were providing and dictate appropriate responses so that I could actually stand up and do turns down the hill.
  • I got better and better and went into the chalet at lunch stoked I was doing so well and eager to get back onto the hill after lunch
  • After lunch I continued to get better for about 90 min. It was feeling easier and easier and I was getting more and more confident.
  • Then suddenly I started to feel like I was regressing. Things I’d been able to do just 30 min before suddenly became very difficult. I began to fall a lot more. I started to get frustrated and finally decided to call it a day

This was an example of “acute” nervous system fatigue and is very common when you’re working hard at learning a new skill. Your nervous system is working so hard to provide information to your brain about what you’re doing and then execute the brain’s instructions in response that it eventually fatigues and suddenly you lose the ability to learn the new skill effectively. Fortunately you recover quickly from this fatigue. The next day (or maybe within two days) you should be ready to go again with a nervous system fully ready to help with learning new challenges.

In the case of more “chronic” nervous system fatigue this loss of ability to gather information about body position/movement, control movements and generate forceful movements becomes impaired over time. Slowly from day to day you sort of feel more and more “off” until you reach the point where your ability to do movements you’re quite accomplished at is seriously affected. You’ll also find it difficult to exert as much power as you normally do.

This fatigue generally takes a long time to recover from – we’re talking weeks – so it is best avoided.

Fortunately, there are some signs that can tip us off to this type of fatigue developing, such as:

  • general fatigue
  • lack of interest in training
  • irritability
  • change in sleep patterns
  • slow deterioration of strength and feeling of power or explosiveness
  • slow deterioration of feeling totally in command of your technique

Feeling any of the above for a day or two is not necessarily a problem. But if you see a trend developing it is time to take some action. I’d recommend to those reading this that that action be contacting me and discussing the situation. Then together we can come up with an appropriate plan to mitigate the fatigue becoming a major issue requiring a long recovery time.

In contrast, muscular fatigue, is the result of the inability to maintain contractions at the desired rate due to lack of energy or excessive buildup of lactic acid. Lack of energy can result in lack of adequate fuel for aerobic metabolism, and we should all be aware at this point about the issues involving lactic acid as we’ve talked at length about them when discussing pacing.

Hopefully this information helps. Please feel free to ask questions should you have any or need any clarification.

Have a great snowboarding trip!

Larry

Basic and All Access members have access to the Forum and the ability to ask coaches questions: Join at paddlemonster.com

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