Neural Fatigue

[Sasha Pachev]

I would like to start a discussion of the neural drive and neural fatigue. Feel free to share what you know, suspect, or have experienced. I believe that understanding of how the neural drive works is key to improving the Quality X that we discussed in earlier posts.

So, for a review. Here is an indication that you are experiencing neural fatigue. You start a race or a tempo run at your normal race or tempo pace. Nothing seems wrong, maybe you may feel a bit reluctant to go, but it is easy to blame on just being lazy and not looking forward to the effort, nothing more serious than not wanting to get out of bed on a Sunday morning and go to church. You hold the pace for a mile or two, sometimes more, and all of a sudden you are 20 seconds or so slower than your target pace, your legs feel fine, your breathing is fine, your heart rate has dropped good 10 beats per minute, but for the life of you you cannot go any faster. When asked why you will be inclined to say "my legs feel dead". But they are not sore. If you stopped, you would have no clue that anything was wrong. In fact, without a watch and a properly measured course you would not even know that you have slowed down.

In my experience I've noticed that good sleep and proper nutrition tends to prevent the problem from being so drastic. The lack of sleep tends to aggravate it. I have particularly noticed it on the odd hour legs of overnight relays. It can be blood sugar related, I have seen a drastic change after raising a blood sugar level with a snack, and I have seen it come on following a day of stomach distress and not much eating. But it appears to me the blood sugar level is more of a trigger when the stars align than the leading factor. It is possible not to hit the fatigue symptoms with a fuzzy head at the end of a 20 mile run, while at the same time experience them after only a 3 mile warm-up with a very clear head. I've also managed to not experience it at all after a day of stomach distress and still not being over the hill. I've noticed some correlation with speeding on base runs. Running as slow as 6:30 per mile for me (which is a good 45 seconds slower than my marathon race pace on the same terrain at the same altitude) for several days back to back almost certainly brings it on. Running hard or even just brisk uphill too frequently has correlated with it as well. It is also more likely to come after a marathon, although this is not as sure of a factor as the others.

I have wondered if the end of a marathon slow-down for me is neural fatigue related as well. Unless it is DesNews the legs feel fine, the head works, I do not feel weak, there is money on the line, there is a ram to sacrifice a minute or two ahead, there is Abraham with a knife behind hoping I would be his ram, and I am stuck at around 6:00 - 6:15 pace, and cannot go any faster for the life of me.

[Paul Petersen]

I've never experienced any of that.

When you talk about "neural fatigue", you lose me every time. Perhaps I'm too simple-minded. Or perhaps my ability to pick things apart is limited (I'm a lumper, not a splitter).

Quality X = talent/genetics.
Neural Fatigue = Fatigue

[Josse]

I am with Paul on this one.  BTW I love your running guy.

[Jon Allen]

Josse- is he running guy or dancing guy?

Sasha- I also get lost/confused when you talk about neural fatigue.  And, like Paul, I have not experienced it.  Like everyone, I have days when I can't run as fast and feel tired (like Wed this week).  But I know that I feel bad within the first few feet of the run- I don't run 2 miles fast and then all of a sudden slow down.  I also slow down at the end of some races/runs, but I know why- I'm tired.  If I stop running, I can still feel I'm tired.  But again like Paul, I don't try to analyze things- I know my body has limits in both workouts and races so I don't worry when I hit them.

[Sasha Pachev]

Josse:

You should know what it is like. You get it almost every time you race or run a time trial. Maybe with the exception that you feel tired afterwards anyway. But it is common for you to run 6 miles at 7:00 breathing fairly hard, then slow down to 7:40 in a couple of miles, and be stuck there while not breathing very hard at all.

With Paul I am not surprised. His HR can go up to high 190s. His muscles or heart will quit before his neural drive will. With Jon,as fast as he is at the top end, and as slow (comparatively) as he is in longer races, I would not suspect neural drive problems either. Aerobic system would be sufficiently limiting to not see them.

[Jon Allen]

With Jon,as fast as he is at the top end, and as slow (comparatively) as he is in longer races

Sasha- what do you mean by this?  That I have good speed (fast) at short distances but slow at long races?

[Jeff Linger]

I know exactly what Sasha is talking about. But, what he calls neural fatigue, and the rest of you are calling general fatigue, are basically the same thing. Our nerves are simply messangers between our brain and our working parts. Except that they sense things that our mind cannot, and cannot over-ride. I was just watching a show this week about how important nerves are. In the show they talked about a woman who fell in the wilderness, had a significant compound fracture to her leg, dragged herself for 2 days to a place where she could be found. Although in pain, for the most part the pain was manageable. As soon as her rescuers arrived the pain became so great that she passed out. What we're talking about, and I think what Sasha is getting at, is that fatigue is almost always connected to nerve impulses. We're not talking about the fatigue that occurs because you've gone beyond your Vo2 max capacity, or because you've gone beyond your lactic capacity. Its your body's capacity to recognize when you are not prepared to accomplish what you're trying to make it do. On the flip side, the same mechanisms that are sending messages to your working parts and telling them they can't handle the workload, will also send messages to those parts to tell them to go into overdrive when you really can't handle the workload, but your survival depends upon it. The only real question becomes, can we over-ride our subliminal neural messages to produce faster times ..... and should we? Our nerves are sending these messages for very good reason. The show I watched talked about how vital pain was to humans. Pain is a mechanism that saves us from further pain. It is a sensation that is either suppressed or enhanced beyond normal depending on our needs. If we're trying to over-ride neural messages simply for the sake of a faster time ..... we're trying to over-ride our body telling us that if we don't listen, we're going to get injured.

[Josse]

Sasha I get what you are talking about but I think you have just given fansy name for what Paul said Quality X = talent/genetics.
Neural Fatigue = Fatigue
I think you over analize it all and it so basic.  I get tired because I am probably over training, not getting enough sleep, and low on iron.  So I can't do quility workouts.  So to fix it I need more sleep, to cut back on miles and I need to take an iron supplement.  But scense I don't want to cut back on mileage then I can only change the 2nd two, which I am working on at the moment.
I think Jeff sums it up very nicely:)
Jon I think it is a running man, this is the way I run when I get neural fatigue

[Paul Petersen]

Jon I think it is a running man, this is the way I run when I get neural fatigue

For the record, the avatar is Mugatu from Zoolander, and he is dancing in a hypnotic fashion (appropriate for neural discussions). Relax.

[adam]

Sasha, I addition to the normal physical limitations brought on by poor nutrition, sleep, stress, fatigue, etc, I think you see this sometimes because (whether it is true or not, I don't know) somewhere subconsciously your brain is bored of the same courses day in day out. It expects your 5 mile tempo course runs too much as well. Even if you are feeling great it says "I run this stretch everyday at slower paces so why the heck does he want me to go faster?" So in order to make things intresting it lets you analyze every little bit of your training rather than train faster because it is easier to keep your mind occupied with stats and numbers than it is for it to focus on bringing your body into a sustained 5:00 pace. This thinking possibly shuts down your running ability. Then when you race somewhere, it takes on that mental state: "I'll work for a bit, but this isn't what I'm really trained to do- I'm trained to think consistently". The amount of time you spend analyzing things everyday will drain your nueral abilities. If you have ever tried to go for a run after a multiple hour exam, or huge work project, you know you feel a little "brain dead" after. I am not saying this is the whole problem, but it is probably a part. It probably doesn't help that the rivertrail has 100m triangles- which are just too enticing to look at and do that math from, even on an easy day run. 16 marks per mile for 15 miles= around 240 times minimum when you can calculate splits on your run.

I believe course and training variation keeps the mind focused on the task at hand-- running. And I believe that this can improve some neural issues. If I paint the same section of a fence white every day, it will not get any whiter no matter how much I look at every square inch of the fence, every bump and hole, the type of paint, the type of brush, the brush stroke, how many brush strokes I can do in a minute, etc. I might get better at painting, my hand might get stronger, I might be able to fill in a few unpainted parts, but ulitmately my brain is just becomes bored and just stops wanting to paint, even though I want/need to keep going. I know they're is something there, some potential or reason, but can't bring it out. If I paint a mural on that fence, and my brain reactivates- designs, plans, colors, all the skills come back- It wants to paint and keep going. I can get lost in the painting and create something amazing without forcing it. If I think to much about the mural though, I get stuck and can't go on--the creative juice is gone.

Sorry about the length, I know it probably doesn't make much sense and is a little lame. That's just how I see it sometimes. Less thought, go run and run fast. Rest, recover. Train this system, train that system all with a productive plan. Use all the paints, even if its a color I don't like it or I find has no purpose or no effect, it can still be combined with something to bring out the bigger picture.

Try running your 5 mile tempo on a course you don't normally run on. Do it at least 4x minimum in 6wks. Go XC even. Don't even take your watch, HR- give all that to someone who can time and do all that for you. Run that course as best you can and have them call out splits as you pass. Do only the math that matters there: "I want 26 mins on this course, he just said 10:40 at 2, I better get moving". Focus on moving faster, pushing past the nueral block. If no luck the first time, go back with the determination to get it again. Then after your time away, go back and try to run your 5mile rivertrail tempo. See if there is improvement there. I believe that there would be, and that would translate into your races. I believe you would begin to respond better to splits. Shoot, even take Flanagan's 10k as an example. I highly doubt she spent the last few laps thinking about anything but staying up running, not even the place she was in.

ok. enough. sorry again for the long, drawn out post.

[Paul Petersen]

Great post Adam.

[Jon Allen]

The amount of time you spend analyzing things everyday will drain your nueral abilities. It probably doesn't help that the rivertrail has 100m triangles- which are just too enticing to look at and do that math from, even on an easy day run. 16 marks per mile for 15 miles= around 240 times minimum when you can calculate splits on your run.

Interesting.  I will admit I don't know any other runners who ever keep track of quarter mile splits except for track speedwork (once per week for 4-6 miles, max).  I don't even track mile splits, I just run.  But everyone is different.  Adam raises some interesting neural fatigue points, which is what Sasha says limits him often.

[Michelle Lowry]

I agree with Adam that you are perhaps in a rut, Sasha.  I like your idea of focusing on 5:00 pace, but perhaps you need to do some systematic intervals, like 1k's or 1 mile repeats.  Doing 5:00 whenever you feel like it, after a VPB or for 600m once a day isn't going to do it.  The key is to combine fast with endurance.  That probably takes a combination of intervals and faster, shorter tempos, then extending the length of those tempos as you are able to.

I've enjoyed this whole thread and agree with most of what has been said.  I think the whole listening to your pain Jeff mentions is a difficult balance.  We definitely need to listen to our bodies, but during key workouts and races, so long there is not acute pain, I say you've got to ignorei it.  The second half of a race is generally learning to ignore and work through pain, to push past barriers our bodies are trying to set up for us. 

[Dave Holt]

Adam - I am having some fence problems at my house.  Any suggestions?

[Superfly]

Adam- Steve H. is also having some disco ball issues. Any thoughts?