by, March 8th, 2009 at 06:08 PM (1740 Views)
A friend of mine recently referred my attention to a study that, albeit based on a relatively small sample size of 16 test subjects, may just explain a portion of what ails me better than many of my own armchair speculations (slow viruses, sickness unto death, dysthymia, weak character, etc.).
The paper is entitled, Mental fatigue impairs physical performance in humans by Samuele M. Marcora, Walter Staiano, and Victoria Manning
The citation, for those of you who require such things:
J Appl Physiol 106: 857-864, 2009
You can also download a free .pdf, at least if you act quickly, by visiting http://jap.physiology.org/cgi/conten...ract/106/3/857
In a nutshell, what these British researcher wanted to see is if being mentally burned out and stressed and used up, a state of mind yours truly suffers almost nonstop of late, might have a measurable impact on purely physical performance, AKA, a bout of endurance exercise (not swimming, alas, but the easier-to-measure-in-a-laboratory-setting "sport" of stationary cycling.
As the authors explain at one point in their manuscript:
Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity. Although the impact of mental fatigue on cognitive and skilled performance is well known, its effect on physical performance has not been thoroughly investigated....
They go on to acknowledge that the only quasi-scientific info they could find on the subject was the more or less subjective experience of two 19th Century pointy-heads, who, like your narrator, appeared to make their living from thoughtful pontifications:
To the best of our knowledge, the only published observations date back to 1891 when Angelo Mosso reported in his seminal book on fatigue that muscle endurance was reduced in two fellow professors of physiology after long lectures and oral examinations ...
Because I do not want to repeat this error in my vlog today, and contribute, via pseudo professorial lecturing, even more mental fatigue to my already depleted state of mind, I shall short-shrift their experiment. Assume all random cross over and assorted other methodological precautions were taken. Then:
- they got 16 people to agree to get tested to exhaustion on stationary bikes
- before the exercise, the volunteers either underwent a mind-numbing 90 minute computerized test, which demanded vigilance and quick-wittedness; or they watched an emotionally neutral documentary. The computer test left them wrung out, cranially speaking. The movie left them relaxed and rested.
- during the subsequent physical test on the exercise bikes, the subjects also underwent a variety to measurements to see if their hearts, lungs, muscles, etc. were altered by either the cognitively challenging or mentally relaxing pre-tests. No physical differences emerged on any measured parameters, from heart rate and oxygen consumption to blood pressure and lactate.
- despite absence of any physical differences, the ones who tried to exercise while mentally tired out did much worse endurance-wise, reaching the perceived point of exhaustion 15 percent earlier than when mentally rested.
Though the study did not identify a mechanism, the good doctors speculate that mental fatigue may affect the brain's "no mas" lobes, priming us to throw in the towel earlier than we otherwise might. Brain fatigue, they speculated, may also depress levels of dopamine, which when available in robust quantities, keep us turbocharged to continue.
In conclusion, if I am interpreting the findings correctly, the basic maguffin is this:
- we are designed to stop exercising when we reach the point of perceived exhaustion, i.e., when despite our best intentions, we feel we "just can't go on any further."
- the conventional wisdom has been that this point is reached primarily when our "physical" resources have been used up--no fuel left in the tank, too much lactate in the blood, we've bumped up against the ceiling of individual VO2 max, the fast and slow twitch muscles can no longer recover sufficiently to contract again, etc.
- now, however, it looks like prolonged mental challenges beforehand impair our ability to persevere, too, and not in trivial ways. Mental fatigue appears to do this not by sapping physical strength and endurance but rather by lowering our point of perceived exhaustion.
Maybe my friend Bill was right after all when he observed that my worsening AT times in swim practice these past few months have been more mental than physical.
THe study might also explain why my sprinting times do not seem to have been ruined nearly as much as my longer distance efforts. Races like the 100 freestyle, for example, are over so relatively quickly that even if I do throw in the towel at an earlier moment of perceived exhaustion, the total amount of race time spent dilly-dallying and wimping out is not enough to altogether ruin my performance. (Take, for example, the 100 free where I perceive exhaustion with 10 yards to go. Even with some slowing down, momentum alone gets me to the final wall. In the 1650, perceived exhaustion still hits me at this point, that is, 90 yards into the race. Alas, momentum alone will NOT get me through the remaining 1560 yards.)
Perhaps a test for the theory is coming.
A quick review of upcoming events in my life:
- Tomorrow, March 9th, meet with new accountant to plan for IRS audit defense
- Tomorrow, March 9th, turn in my soy story to editor
- The upcoming week, March 10th-March 17th, most likely learn if I have been nominated for 4th consecutive National Magazine Award, the odds of which are overwhelmingly unlikely
- The upcoming week, March 10th-March 17th, hear back from my editor about the soy story
- March 18th, undergo the 4-hour IRS audit, AKA, Inquisition.
- The rest of the month, March 19th-April 3rd, deal with consequences of all of the above
- April 1st, find out if my 2-year contract, which expires April 1st, will be renewed
- April 4th, begin the local AMYMSA regional meet
- April 24th-26th, if I am not homeless or in a hospital for the criminally bankrupted and driven insane by the IRS, drive down and swim Colony Zones SCY championships
Depending on how the pre-meet preliminaries turn out, it is possible that my swimming performances--especially in the longer races--could be impacted for the better or for the worse.
For instance, if the editor hates my soy story, the IRS lady finds fault with my previous returns, I fail to get a nomination, my job contract is not renewed, I lose my house, and am driven insane, I might not swim that well.
On the other hand, if my soy story is beloved, the IRS determines they owe me money, I not only get nominated once but twice and win for both stories, my job contract is renewed with huge raise, my house is declared a National Historical Treasure by virtue of my occupancy, with all expenses and taxes heretofore to be paid by the National Park Service, and my sanity remains thoroughly within my euphoric control, well then...
Alas, even I see why this is not to be.
A video showing my friend and coach Bill White racing another friend Heather Towne Fisher in the 400 IM, with Bill trying to lap Heather, and Heather trying not to be lapped.
I call this film, The Jaguar and the Wildebeest. Really, no need to watch it. However, at approximately the 1:10-1:15 mark, you can see what the waves are like in an Eastern US podunk 5-lane YMCA pool, and be thankful for the luxurious accommodations where you get to race in your neck of the woods.
[ame="http://www.youtube.com/watch?v=-8HbNmtETdM"]YouTube - Untitled[/ame]