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Research-based coaching: an introduction

[This article originally appeared in the February 2000 issue of Northwest Runner magazine.]

If you needed training advice about how to prepare for a big race, whom would you consult: a coach . . . or a scientist? Most of us would opt for the coach, especially given the common perception that scientists tackle esoteric problems with little relevance to the real world. Yet some scientists know quite a bit about endurance exercise; after all, they've been studying it for decades. In this article, I hope to convince you that, although coaches may offer us a wealth of wisdom, the scientists should not be ignored, either.

Before going any further, I should admit that I myself am a scientist -- a junior scientist, really, as I have yet to complete my graduate education. My ideas about endurance training are therefore rooted in the so-called "scientific method," which in essence is a technique used to settle scientific arguments. For instance, if Scientist A thinks he's discovered a wonder drug which will cure heart disease and Scientist B thinks the drug is worthless, what usually happens is that they (or perhaps the wily Scientist C) will do a series of experiments to see who's right. If these experiments demonstrate that the drug is indeed effective, it may then be prescribed by doctors and used by patients.

If this scenario seems utterly irrelevant to distance running, consider an argument of a different sort: Coach A says that mile intervals are the most important ingredient in an endurance training program, while Coach B claims that mile repeats have little if anything to do with racing success. Whom should you believe? I claim that this issue and many others like it can be addressed using more or less the same method as that discussed above. In other words, why not examine the scientific studies of mile intervals to see whether there is clear evidence that they work? If most of these studies come out in favor of interval sessions, then intervals should in fact be prescribed by coaches and used by athletes. However, if most studies fail to show that interval workouts are any more beneficial than "placebo" workouts, one should think twice about incorporating them into a training schedule.

We thus arrive at the concept of Research-Based Coaching, or RBC for short. The central tenet of RBC is simply that one should train and prepare for races using techniques that have proven effective in unbiased scientific studies.

What's the big deal?

At first glance, RBC may not seem like a particularly novel idea. Don't all coaches guide their athletes according to scientific principles? Well, yes and no. Most coaches are indeed well-grounded in the fundamentals of anatomy, physiology, and biomechanics. When it comes to the actual design of training programs, however, many adopt or devise theories which lack strong experimental support. Take, for example, the notion of "periodization," the popular belief that one's yearly training program should be organized into a sequence of phases such as a base-building phase, a strengthening phase, and a sharpening or speed development phase. Some coaches swear by extremely detailed periodization plans full of macrocycles, mesocycles, and microcycles. The importance of these details is dubious, however, since there is hardly any scientific research on how one should stagger the various training phases or to what extent they should overlap each other. I'm not saying that periodization is a bad idea; even to me, it has some intuitive appeal. My point is that, in general, one should not assume that a given coach's methods have been validated in a controlled laboratory environment.

Another possible objection to RBC is that it needlessly complicates the coaching process. Can't we infer that, if a coach has developed lots of great athletes over the years, his/her methods must be sound, and we would be wise to train in the manner he/she recommends? Again, the answer is: well, sort of, but not exactly. I agree that, to a certain extent, it's hard to argue with success; if a coach has a track record of helping people run faster, he/she must be doing something right. However, coaching success depends on so many factors -- recruiting, budget size, access to facilities, and (unfortunately) the use of steroids and other drugs, to name just a few -- that it is often misleading to attribute a coach's triumphs to his/her training philosophy per se. Besides, different coaches have taken different paths to the victory podium, so whose approach should you adopt? I contend that it makes sense to select whichever methods are supported by scientific studies published in reputable journals.

RBC in action: an example

As an example of how RBC can be applied to real-life situations, I'd like to explore the question of what one should eat in the week before a marathon race. The main goal of manipulating one's pre-marathon diet is to arrive at the race "loaded" with glycogen, a storage form of carbohydrates -- hence the term "carbo-loading." There are two main theories on how to do this. The first holds that you should just pig out on high-carbo foods for the final three days before the race. The second is a bit more complicated; it advocates doing a hard "depletion run" about a week before the race, followed by three days' worth of low-carbo meals, followed by three days of high-carbo feedings.

Carbo-loading has been studied in a number of different laboratories over the years, and this research has shown that both of the above-mentioned strategies can boost muscle glycogen stores to higher-than-normal levels. As I prepared for my first marathon, though, I couldn't help but wonder: does one work better than the other, or are both equally effective? I went to the library to find out.

As is often the case with scientific research, the story that emerged was not as clear-cut as I would have liked. I could only find two studies that attempted a head-to-head comparison of the two carbo-loading methods: Bergstrom et al. (Acta Physiologica Scandinavica 71: 140-50, 1967) concluded that the deplete-then-load procedure leads to greater gains in glycogen reserves and performance, while Sherman et al. (International Journal of Sports Medicine 2: 114, 1981) found no difference in the results obtained by the two methods. However, in reviewing studies that only utilized one method or the other, I discovered that the deplete-then-load protocol can often increase muscle glycogen content to 80-100% above normal levels (Karlsson & Saltin, Journal of Applied Physiology 31: 203-6, 1971; Goforth et al., Journal of Applied Physiology 82: 342-7, 1997), while the simpler load-only protocol generally yields more modest increases of 30-55% (Madsen et al., European Journal of Applied Physiology 61: 467-72, 1990; Bosch et al., Journal of Applied Physiology 74: 1921-7, 1993; Rauch et al., International Journal of Sport Nutrition 5: 52-60, 1995; Tarnopolsky et al., Journal of Applied Physiology 78: 1360-8, 1995; Hawley et al., European Journal of Applied Physiology 75: 407-12, 1997).

Armed with this information, I decided to give the deplete-then-load regimen a try, first during a normal training week and then during the week prior to each of my two marathons last year. Of course, I can't say for sure whether I ran better on the deplete-then-load diet than I would have otherwise; in my debut race, I had to slow down during the last 5K, while in my more recent effort, I felt great except for a stomach cramp during miles 21-23. Nevertheless, I feel that I used the RBC approach to make an informed decision which maximized my chances of marathon success. Finally, I might add that, in forcing me to create low-carbo meals for the first stage of the deplete-then-load diet, RBC has bolstered my culinary creativity as well as my glycogen supply. I've dined on quiche and sausage for breakfast, chicken wings and olives for lunch, and bunless hamburgers and macademia nuts for dinner. Eat your heart out, Heather Nakamura!

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