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Be specific!

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

Over the past ten months, I have written about scientific studies on strength training, tapering, stretching, altitude training, and various nutritional issues. I hope my articles have demonstrated that scientific research can be used to optimize one's workout regimen and diet. However, in trying to apply hard-core science to practical training issues, at least two major problems arise.

The first problem is that endurance athletes ask very focused questions for which there may not be any good data. "How long should my tempo runs be?" is one example; it's a reasonable question, but the scientific community doesn't have the answer, at least not yet. The second problem is that, even when a particular issue has been studied, it can be a royal pain to go look up the research and make sense of it all. Thus, while a research-based approach to training can be very rewarding, it can also be very frustrating, as one may devote hours to the pursuit of an answer which may or may not exist.

Given these difficulties, you may ask, "Does this research-based coaching advice have any sort of overall theme? Must each training-related question be addressed with a separate trip to the library? Aren't there any general principles which we can apply across the board?"

As it turns out, there is indeed an important "overall theme" which emerges from the scientific literature on training: the principle of specificity. According to this principle, when one trains one's body to do a particular task, the body gets better at that task, but it doesn't necessarily get better at other unrelated tasks. The improvement is therefore said to be specific to the training task.

Bowling or lawn darts?

At first glance, the concept of specificity may seem rather trivial. If a friend wanted to become a better bowler, we obviously wouldn't advise him/her to play lawn darts or air hockey; we'd suggest that he/she go bowling more often. Nonetheless, given the enthusiasm with which some fitness gurus tout the benefits of cross-training, it's important to remember that the best training for runners is, in fact, running. For example, in the classic study of Pechar et al. (Journal of Applied Physiology 36: 753-6,1974), a group of 20 male college students trained on treadmills three days per week for 20 minutes per day at 85% of their maximum heart rate. After eight weeks, these subjects had increased their VO2max (maximal oxygen uptake, a measure of endurance performance) on a treadmill by 6.8%. Meanwhile, a separate group who underwent similar training on stationary bicycles only boosted their treadmill VO2max by 2.6%. Thus, although cycling did improve treadmilll performance somewhat, it was less effective as a training stimulus than treadmill running.

These results might be surprising to some, given that both cycling and running exercise the heart, lungs, and legs. However, as noted by Tanaka (Sports Medicine 18: 330-9, 1994), cycling and running stress the legs in different ways; cycling places a heavy load on the quadriceps muscles, whereas the plantar flexors (soleus and gastrocnemius muscles) are more important for running. Thus, it makes sense that running performance improves most in people whose legs are trained specifically for running.

The study described above is only one of many to examine the degree to which training in one sport can improve performance in another sport. These studies have been reviewed by Franklin (Medicine and Science in Sports and Exercise 21: S141-8, 1989) and by Tanaka (Sports Medicine 18: 330-9, 1994); both conclude that, while fitness in one sport can sometimes carry over to similar sports, there are also many instances where cross-training does not enhance performance as much as sport-specific training does.

By the way, I freely acknowledge that cross-training is useful to runners who (a) are injured, (b) are susceptible to running-related injuries, (c) want to spare their legs from too much pavement-pounding, (d) have very weak muscles that aren't used in running, and/or (e) need variety in their training to keep it fun. My point here is simply that, if you want to do your best as a runner, you should emphasize running in your training -- to the extent that your body and mind will allow, of course.

Getting even more specific...

The above information is just the tip of the specificity iceberg, however. When someone trains his/her limbs to move in a certain way, the adaptations that occur in the relevant muscles and nerves depend on the speed, direction, and forcefulness of the movement, as well as the joint angle and the person's posture. The evidence for this (reviewed by Behm & Sale, Sports Medicine 15: 374-88, 1993, and by Morrissey et al., Medicine and Science in Sports and Exercise 27: 648-60,1995) is considerable, and the following two examples may help us appreciate just how specific a training adaptation can be.

In a study of movement speeds, Coyle et al. (Journal of Applied Physiology 51: 1437-42, 1981) trained one group of college men to perform fast knee extensions and a second group to perform slow knee extensions. By the end of the study, the slow-trained group had improved most in its ability to perform slow knee extensions, whereas the fast-trained group had become superior at fast extension speeds.

Similarly, in a study of joint angles, Graves et al. (Medicine and Science in Sports and Exercise 21: 84-9, 1989) subjected one group of men to knee flexion training over a range of motion of 0 to 60 degrees of flexion -- at 0 degrees, the leg is completely straight -- while a second group trained over a range of 60 to 120 degrees. As you might guess, the 0-to-60 group exhibited impressive strength gains when tested with the knee joint positioned at between 0 and 60 degrees of flexion, whereas the 60-to-120 training group improved its strength more on the tests conducted at angles of 60 to 120 degrees.

Although these studies (and most others reviewed by Behm & Sale and Morrissey et al.) concern strength training rather than aerobic endurance training, they make a very important point about athletic training in general. That point is as follows: if we want to get better at a particular athletic task, it is not enough to exercise the muscles involved in the task; we must use the muscles in a way that mimics the task itself. For runners, in other words, it is not enough to run; in our running, we must simulate the race we're training for. If we're preparing for a hilly cross-country course, for instance, we should practice running uphill in our training (Freund et al., Medicine and Science in Sports and Exercise 18: 588-92, 1986).

Don't ignore the obvious!

Does all of this sound intuitively obvious? It should -- and yet I think that a lot of us, myself included, don't always train as specifically as we should. To cite an extreme example, the coach of a friend discourages marathoners from doing long runs because he figures that going the distance is simply a matter of mental toughness. Such advice directly contradicts the principle of training specificity; if you expect to be on your feet for three or four hours during the race, you should give your body some practice at this task in advance of the race itself. And here's another one: why do some people run endless sets of intervals at speeds much faster than race pace without ever bothering to run at race pace? Although the super-speedy workouts are no doubt useful, the specificity principle suggests that training at race pace should be a priority in everyone's workout schedule.

OK, so one should tailor one's workouts to the race terrain, distance, and pace ... but that's not all. Is the race going to start at the crack of dawn? If so, you should consider training in the morning (Hill et al., Medicine and Science in Sports and Exercise 30: 450-5, 1998). Are the temperatures expected to be high? Better practice running in the heat (Pandolf, International Journal of Sports Medicine 19: S157-60, 1998). Will you be stopping for Gatorade every few miles? Don't try this for the first time during the race; do it during your workouts, too! Is the race likely to be decided in the final straightaway? Maybe it's time to practice that kick.... I think you get the idea.

The concept of training specificity can be fruitfully applied to form drills, plyometrics, and other strength-building exercises as well. In the April 1999 issue of Running Research News, Owen Anderson explains how this should work: "Since the gains in strength ... are specific to the speed of movement utilized during the strength work, it's important to attempt to match your speed of movement as you strength-train with the actual speeds of movement associated with your sport." Furthermore, Anderson continues, "since running is a 'one-legged sport' (full body weight is borne by one leg at a time), it's important to avoid ... seated or lying-down postures while carrying out strengthening exercises; instead, utilize strength routines which require most or all of body weight to be supported by one leg, not by both. Thus, one-leg squats are better than traditional squats, one-leg hops ... are better than two-leg jumping, etc."

In short, the training principle of specificity is utterly logical, is supported by a variety of scientific studies, and can be used to address a wide range of training-related questions. Of course, no single principle can possibly encapsulate everything distance runners need to know about training, but this one comes closer than most. When in doubt, be specific!

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