If you carry out challenging interval workouts during your training, you are studying the true nature of fatigue.

After all, you have probably had the following experience: You decide on a workout, say 10 X 400 in 90 seconds each (we've selected a familiar type of training session and an arbitrary time for each work interval). Your warm-up goes well, and you're off and running!

The pace you have chosen is an ambitious one, but you are feeling great the first time around the track, and you cover the initial 400 in 87 seconds. The second one is 88, the third 89, and from the fourth one on you are struggling a bit to hit your target of 90. For the most part, you stay on track, but one interval, we'll say the eighth, slides up to 92.

The ninth feels really tough, but you hang in there and produce a 90. You have reached the point in the workout at which fatigue should be close to maximal. After all, you are a believer in the traditional concept of fatigue. You know that as you continue to run quickly, for one work interval after another, your intramuscular pH is dropping fast, reflecting the tide of hydrogen ions which are flooding your muscle cells(1). That devastating fall in pH is interfering with the release of calcium ions into your muscles' sarcoplasmic areas (2), making it much-more difficult for your muscle fibers to contract forcefully (3). As a result, adhering to planned pace is becoming a major undertaking.

And then, something magical happens! At the point when muscular fatigue is greatest, when pH has bottomed out, when calcium ions have been locked away for the day, when muscle contractility has ebbed, you uncork your best 400 of the day - an 85! Who said that running does not have its magical moments?

Huh? If muscle fatigue is truly a function of metabolic events inside muscles, that last 400 should have been the slowest, not the fastest interval of the day. Our views of fatigue - and of what determines running pace during workouts and races - must be wrong!

Indeed, that is what recent research carried out at the University of Cape Town, the University of Stellenbosch, and the Sports Science Institute of South Africa is telling us. In this investigation, eight healthy males (average age = 22 years) completed "anaerobic-capacity" tests in the laboratory on a Monark friction-braked cycle ergometer (4). To gain a better understanding of the nature of fatigue and of pacing strategies during high-power exertions, the South-African researchers used an element of deception with the subjects. Specifically, the young men were informed that they would be completing four 30-second maximal trials, as well as one 33-second and one 36-second maximal effort on the bike. In reality, they completed two trials of 30 seconds, two tests of 33 seconds, and a duo of 36-second exams.

The deception took place in the following way: Prior to one of the 33-second tests, the cyclist were told that it was actually a 30- second exertion, and the same was true for one of the 36-second affairs. The researchers hoped to determine whether the subjects would subconsiously alter pace or strategy during the "informed" 36-second trial (when they were told that the trial would last for 36 seconds), for example, compared with the "deception" 36-second trial, when the cyclists thought they would only be cycling for 30 seconds. The cyclist were allowed to watch a clock during all of their maximal exertions, but - ingeniously - the scientists had programmed the clock to run more slowly during the deception 36-second trial, so that it would tick off 30 "seconds" during what was really 36-second time frame.

To learn more about Fatigue (the full article can be read by purchasing Vol.22 Issue 2) and many more running related topics. Simply enter fatigue, in the "search archives" box, or enter any subject you wish to learn more about. A subscription to Running Research News is another way to receive valuable information.
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