Robert Motl is a professor in community health and kinesiology at the University of Illinois.  He also just happens to be a former competing cyclist, which makes him doubly qualified to comment on the relationship between caffeine and the pain people feel when they exert themselves intensely in physical terms.  This happens most often during rigorous exercise and for that reason Professor Motl is really studying the relationship between caffeine and the pain people feel during exercise.

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Motl has been interested in caffeine for some time now and even before the current study had already done a large amount of exploratory research on the effects of different doses of caffeine on exercise intensity and anxiety normalized between the two genders.  However, his current examination takes a look at caffeine and exercise from a completely different point of view because it looks at the pain people feel during exercise, a factor that also happens to be one of the biggest reasons for people dropping out of established exercise routines.

The study, which was published in the April issue of International Journal of Sport Nutrition and Exercise Metabolism, used 25 different male individuals between the ages of 18 and 22.  These males were divided into two different groups according to relative measures of low and high daily caffeine intake and the study was then carried out with those two groups in mind.  According to Motl, he was interested not only in tracking the relationship between caffeine and pain felt during exercise, but he was also interested in evaluating what the difference would be between bodies that were already tolerant of caffeine and those that were not.

The reasoning behind tracking this particular variable is simple.  The regulation and processing of pain in the body is performed primarily by the adenosine neuromodulatory system, a bodily system located partially in the brain and partially in the spinal cord.  The adenosine in this system is responsible for processing the pain and it also happens to be a substance that has shown to be blocked and inhibited by the presence of caffeine in the system.  For this reason and considering the effects of tolerance on other aspects of caffeine such as the amount of it a person needs to take to stay alert during periods of fatigue, tracking the study according to current caffeine intake was a perfectly logical thing to do.

Following the adage of the simplest approach is usually the correct one; Motl designed an experiment that was simple to track and simple for the 25 subjects to follow.  It started with an exercise test that was done on a fitness bike on a person-to-person basis for the purpose of establishing an aerobic power baseline to compare against future results.
Once this test had been completed, each of the subjects was then subjected to two different half hour exercise routines identical in their high intensity level.  In the 24-hour period preceding each routine, the subjects were under strict orders not to consume any caffeine whatsoever as well as to show up an hour early to each exercise session.  At the point they showed up, the subjects were then given a pill to swallow.  One time it was a placebo and another time it contained an amount of caffeine equivalent to around 2-3 cups of coffee.  Neither examiners nor subjects were aware of which was which beforehand, establishing the double-blind model that is critical for drawing meaningful results from such experiments.

When the exercises were actually going on, the data collected ranged from oxygen consumption to work rate and heart rate, not to mention the subjective view that the person exercising had on the amount of pain they were feeling during the exercise.  Since the high-intensity workouts consisted mainly of aerobic work on a fitness bike, pain in the quadriceps was used as the measure for the overall pain data for each subject.

Motl sat down and took a look over all of the results and what he found was something that in his own words was unexpected.  What he essentially found was not only that caffeine did have the ability to reduce the amount of pain felt during the workout, but also that the benefits derived from the consumption of caffeine were equally shared between people that did not have a caffeine tolerance and those that did.  Considering the fact that tolerance to caffeine makes a huge difference in the amount that needs to be consumed for the mental alertness benefits to kick in, the results regarding pain reduction were quite surprising, to say the least.

Because of this surprising result, there is actually quite a bit more to learn about how caffeine exactly works.  Its ability to create benefits regardless of tolerance issues in certain areas is an ability that is not wholly unique, but certainly rare relative to most substances that follow the general principle of diminishing returns over time.  Understanding more about the biochemical properties of caffeine is critical to understanding how this is possible and according to Motl, that will be the next goal of his research.

Specifically, he is now interested in taking his analysis to the next level and using rodents to analyze the effects of caffeine closer.  He is interested in not only confirming whether the law of diminishing returns does not apply to caffeine and pain reduction during exercise, but he is also interested in developing a biochemical reason for why this is the case.  If it is true that caffeine tolerance is a problem in some properties and not in others, there needs to be a scientific reason why.  The main goal Motl has moving forward is to find that reason and the best place to start with that is through rodent testing.

According to Motl, “If we can get at the biological mechanism, we can begin to understand why there may or may not be this kind of tolerance.”  In the end, these results are incomplete because of the present lack of understanding of that mechanism.

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