Ross speaks: Fatigue and the brain

Anticipatory regulation of exercise

Apologies for the delay in posting after my lecture last week at UIC - the Chicago Marathon came and went, and since then, travels have taken too much time to post properly.

However, what I've done below is post segments of that talk, which was titled "Limits to exercise performance: World records, fatigue and unphysiological performances".  Unfortunately, Jonathan was a little off at an angle, but hopefully the video is clear enough and the sound good enough to make out the argument.  Just in case, the diagram is shown below the video, so you can follow it there (hopefully).  Also, if you're getting this as an email, the YouTube clips might not play, so you may have to click here to go to the site and view the clip there.

The first video, 3:56 long, presents a model which I wrote about in an article published earlier this year in the British Journal of Sports Medicine, called "The anticipatory regulation of performance: the physiological basis for pacing strategies and the development of a perception-based model for exercise performance" (BJSM, 2009 Jun;43(6):392-400)

The model explained:  Complex anticipation and RPE

Obviously, you're watching a part of a presentation slightly out of context, but hopefully it gives you the basic idea.   This is a topic that has been covered a few times on the site - in fact, there's a whole series on Fatigue for those who are interested.

To summarize, your ability to regulate pace (which is something I'll bet you've never even think about) is vastly more complex than you may realize.  Even the most basic decision of how fast to start a 5km versus a 10km race is the result of innumerable calculations, which take into account previous experience, training, motivation, environment (internal and external) and physiological changes during exercise.

It really is a remarkable system, and one which we believe is primarily regulated by the perception of effort.  This is something you probably also haven't thought about much, but the way you perceive exercise is in fact so enormously complex that science is many years away from understanding it.

There is debate in science about whether your perception and the regulation of the pace is done consciously or sub-consciously, and that's where the debate seems "stuck" (or centered) right now.  I suspect that, as with most things, it will turn out to be a combination, for conscious regulation is obvious (you choose to slow down), but so is unconscious regulation - you don't have to think about starting pace, and you also slow down 'involuntarily' during exercise, even though your perception of effort is not necessarily raised (very important point this).

To explain, the physiological inputs before and during exercise result in a conscious perception of effort, which is then interpreted based on the expected duration and the "template RPE", which is a construct representing what would be considered an acceptable rise in RPE.  This interpretation of RPE underscores why exercise intensity changes dynamically during exercise.  It explains how motivation impacts on performance, and it accounts for the effects of changing conditions on performance.  This is why you speed up at the end of a race, even though your body temperature may be close to limiting, whereas you slow down in the middle, when you are not hot.

The idea that your physiology 'controls' pacing is flawed, because it ignores the importance of context - not all physiological inputs are interpreted equally!

Applying the model to the heat

The next video, shown below (2:30 long), shows a simplified model for what would happen during exercise in the heat.

We know that if your body temperature hits 40 degrees (maybe a little higher in highly motivated elite athletes), your ability to exercise is limited - this temperature is associated with nervous system failure, lack of co-ordination, dizziness, and a failure to activate muscle.

Put simply, if you hit an internal temperature of 40 degrees, your race is basically over - you either walk to the finish line, or you fall over in a cool spot and hope to cool off!

But luckily the body is too smart for this - the pacing strategy is adjusted in advance of this failure.  The previous video, on the RPE and the model for regulation, explains how this would happen.  What this second video is showing is that the 'calculation' is made in order to balance the requirements for fastest possible time with physiological 'safety'.

Obviously, stopping at the 36km of a marathon is failure.  So too is death from heatstroke.  But, equally bad is running twenty minutes slower than you could have done, because your brain has been "too conservative".  So the balance is achieved by forecasting the physiological outcome of current behaviour.  Put simply: "If I continue at this pace, storing this heat, will I finish the race before I run into danger?"

On a hot day, when heat storage is higher thanks to reduced heat loss, the answer may well be "NO", in which case the brain reduces muscle activation and thus pace, and the race can be completed in a slower, but feasible time.  The endspurt at the end comes when the body temperature is at its highest, but the risk is now absent, because the brain takes into account the exercise duration remaining, as explained previously.

So that is it in a nutshell - it's not all dreamed out of thin air, mind you!  The BJSM paper I linked to above contains all the references and evidence on which this model was built, so feel free to check that out!

Travel update

Just a quick travel update, seeing as how I'm making my way across the nation meeting all kinds of interesting sports science-related people:  I'm now in the Rocky Mountains, at an altitude of 3,500m, where I am learning new respect for Kenyan and Ethiopian runners who train at this altitude all the time!  I run at least a full minute per kilometer slower than normal, but my lungs feel as though they've completed 10 consecutive 800m races.

I head to Boulder tomorrow, where I will meet with a number of coaches, athletes and experts, and I'll be sure to interview and post interesting comments here.  So join us then!

Ross

Chicago 2009 In-race splits

Splits from the 2009 Chicago Marathon

Below is a table with the kilometer splits (those we got) from today's Chicago marathon, which saw Sammy Wanjiru win his fourth major marathon - Fukuoka, Beijing, London and now Chicago.

His time? 2:05:41, one second inside the course record, so mission accomplished, at least from that point of view. The world record eluded him, but the cold, the wind and the pace-making (too fast early, didn't last long enough) didn't allow that.

The splits make for interesting reading. The early pace was unbelievably fast - 5km was reached in 14:34 and 10km was covered in 29:10, projecting a finish time under 2:03. It was hardly surprising that the pace slowed, and the second half of the race would be covered in 63:40, compared to the first half of 62:01. Abderrahim Goumri was sensible and probably ran the closest to an even split - 62:50 and 63:14.

Wanjiru's decisive move came just before 35km, when he shifted to drop the Kenyans who had kept pace up to that point.

The wind certainly played a role - it was coming from the North, and if you look at the table below, you'll see some really slow final kilometers - that's partly due to the race situation, the fast early pace, but also the wind, because the final stretch of the race is run directly into that wind.

Enjoy the splits below!

Thanks for following the coverage!

Ross & Jonathan

KM	Time	Elapsed time	Mile pace	Projected time	Weather
1	2:53	2:53	4:38	2:01:39	37F / 47%
2	2:53	5:46	4:38	2:01:39
3	2:56	8:42	4:43	2:02:22
4	2:53	11:35	4:38	2:02:12
5	2:59	14:34	4:48	2:02:56
6	2:53	17:27	4:38	2:02:43
7	2:52	20:19	4:37	2:02:28
8	2:58	23:17	4:46	2:02:48	38F / 43%
9	2:53	26:10	4:38	2:02:41
10	3:00	29:10	4:50	2:03:04
11	2:56	32:06	4:43	2:03:08
12	no time
13	5:52	37:58	4:43	2:03:14
14	2:58	40:56	4:46	2:03:21	37F / 44%
15	3:03	43:59	4:54	2:03:44
16	3:00	46:59	4:50	2:03:54
17	No time
18	6:02	53:01	4:51	2:04:17
19	No time
20	5:49	58:50	4:40	2:04:07
21	2:53	61:43	4:38	2:04:00
22	2:57	64:40	4:45	2:04:02
23	No time
24	No time
25	8:59	1:13:39	4:49	2:04:18
26	2:59	1:16:38	4:48	2:04:22
27	2:58	1:19:36	4:48	2:04:24	38F / 46%
28	2:50	1:22:26	4:34	2:04:13
29	2:59	1:25:25	4:48	2:04:17
30	3:21	1:28:46	5:23	2:04:51
31	3:00	1:31:46	4:50	2:04:54
32	2:58	1:34:44	4:46	2:04:55	38F / 45%
33	No time
34	6:16	1:41:00		2:05:21
35	2:58	1:43:58	4:46	2:05:21
36	2:54	1:46:52	4:43	2:05:15
37	2:55	1:49:47	4:42	2:05:12
38	3:00	1:52:47	4:50	2:05:14
39	3:01	1:55:48	4:51	2:05:17	38F / 43%
40	3:08	1:58:56	5:02	2:05:28
41	3:06	2:02:02	4:59	2:05:35
42	No time
F	3:39	final 1.195k	4:45	2:05:41

Note: The race doesn't do 1km splits, and so we're reliant on our own 'spotters' out on the course to report to us as the elites hit each kilometer mark, which we then match up against our official race timing. So we apologize for any missed splits, but here's our best efforts to track the race as it unfolds!

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Thank you once again, and keep on reading!
Ross

Chicago 2009 Preview

Predictions from Chicago: Sammy Wanjiru vs...?

Good morning from a cold, still dark, but as yet not too windy Chicago Marathon! Jonathan and I are sitting at the start line near Grant Park, preparing for the race, which sadly we're not running, but tracking from the IT center and medical tent.

Right now, the temperature is -1C, or 31F, and so with two hours to go to the start, the runners are in for a cold first few miles! The wind is a gentle breeze from the north-west, which will make the first few kilometers, in that direction, pretty biting!

All the talk, somewhat over-expectantly, has been around whether Sammy Wanjiru, the London and Olympic champion, can grab the world record of 2:03:59. That expectation, which requires that everything be absolutely perfect, from the pace-making, to Wanjiru's condition, and the weather, means that the race is likely to become about Sammy vs the clock.

We think that's too much to expect, though it's not because Wanjiru doesn't have a record performance in him. I believe on the right day, he would break that record. Earlier this year, he ran London in 2:05:10, after covering the first half in 61:45 (thank to an even faster first 10km). The second half of London was "tactical", and he still wound up running 2:05:10, which suggests that he has something quite a bit faster. That performance in Beijing suggests the same, and so I think Wanjiru is a real 'contender' to get that record.

However, for today, I think it should be seen as a bonus, because there are a few factors that may conspire against him. First is the wind - the northerly wind means that the last part of the race, perhaps 5km, will be run directly into it, and if the record is touch-and-go at 35km, it's likely to slip away. The cold temperatures may also be a touch too cold - it's not certain how Wanjiru will handle it.

Then there is the World Marathon Majors, which Wanjiru is odds-on to win overall. It means he will have a focus on finishing and securing that title, which may moderate his normally aggressive racing style somewhat. And finally, the only incentive I can see is for the course record. At least, nothing has been said about the world record in terms of financial bonus, and so it may be a factor that causes Wanjiru to shoot for a low 2:05 and not risk the Majors with a 2:03-something.

The prediction - Wanjiru to win, off the record

So I think what is likely to happen is that Wanjiru will start on record pace - he has in Patrick Ivuti a pacemaker who was winning this race two years ago. Ivuti is not in the best shape (otherwise, he'd be racing and not pace-making), but he should be good for a 61:50 to half way. After that, who knows? If Wanjiru feels brilliant, he may take it on. However, if I had to stick my neck out, I'd guess he'll assess that it's too breezy (assuming it picks up, of course), too cool, and there may be some pretty good company around him. He'll then slow down, and the section from 21 to 30km will drop the pace to around 2:06-projected.

The final 10 will resemble London and Wanjiru should win, despite some good competition.

So, the crystal ball calls it this way:

1. Sammy Wanjiru - 2:05:55 (after a first half of 61:57)
2. Tadese Tola - 40 seconds back
3. Abderrahim Goumri - a further 25 seconds down

Or, I'll probably be completely wrong! Time will tell!

Live split times:

The next post you'll see from me is a post on the split times. As I mentioned, we're stationed at the finish, and we're going to try to get live 1km splits. The race doesn't do this, by the way (they do 5km splits), and so we've got an ambitious project with 'spotters' located out on the course, and so we're going to do our best to catch the elites as they hit each kilometer.

So I'll do the usual live posting, with a table of 1km times. Let's hope it works! If not, I'll go with 5km times instead!

So join us throughout the morning (or afternoon, for those on the other side of the ocean!) for race coverage!

Ross