Running
< Previous Article
Running: Use, Abuse, and Finding Balance
Written by Dr. SkibaThe interesting thing about the human body is that is can adapt precisely to the stress placed upon it. We take advantage of this fact every time we train: we are making our bodies better at dealing with the stresses of training, so that we are able to race better. We use (and abuse) our muscles, tendons, and ligaments until we manhandle them into the shape we want them in. Or until we get hurt. My purpose in writing this article is to give you a framework for thinking about how your body gets stronger or breaks down in response to what you do to or with it.
Running is probably the most traumatic of our three sports on a regular basis. Sure, crashing your bike is more likely to get you laid up for the rest of the season, but per hour exercised, your body is taking the greatest beating when you are running. Some authors have considered stress in terms of a fatigue curve; that is, a curve that starts out high on the left and slopes down to the right. The idea you should get from this graphic is that you can do a lot of training a little of the time (the top, left corner), or you can do a little training a lot of the time (bottom right), but you can’t do both without entering the red area and eventually getting hurt.
Now, the truth is that this curve is always changing shape, depending upon how strong/durable you are, how well trained you are, how heavy/light you are, etc. The task of your coach is to be able to alter this curve so that you can absorb more training stress more often, so that you can continue to get stronger and not get hurt. (Well, his/her task is to alter you, the curve is just a representation of what your story is. But I digress…)It makes sense that we could look at that same graph above, labeling the vertical axis “% maximal stress on body part”, and the horizontal axis “number of times stress is applied”, and get the same picture. Go into the red zone, and you start developing an overuse injury due to breakdown of whatever body part you are looking at. Stay in the green zone, and you will keep from getting hurt in the short term. Stay too far in the green zone, and you don’t give your body enough stimulus to improve or maintain your durability, and you may get hurt easier. In other words, you might end up making the red zone larger, and the green zone smaller. This is the concept we want to think about in terms of overuse injuries, which are the most common complaints among endurance athletes.
Overuse injuries are caused by mechanical stresses. When running, you are essentially dealing with two kinds of mechanical stress. The first is called the impact peak. It is the stress your body absorbs when your foot first hits the ground. It happens quickly, taking up maybe the first 10 percent of the time your foot is on the ground. The second is the stress your body absorbs while moving through the other 90% of the time your foot is on the ground. This second period of stress, or the active peak, actually puts your body under slightly more stress as your muscles and tendons are loaded and unloaded. In 2003, a fellow by the name of Hreljac at CSU-Sacramento considered this point, and suggested that we’d be wise to consider both in terms of the prevention of running injuries. In other words, it isn’t just slamming your foot onto the concrete, but the way in which your muscles push, pull and stretch in a mechanical sense as you deliver the power to move your body forward.
The problem is that there are conflicting opinions as well as conflicting data regarding what contributes to the injury. Certainly, no one denies what we illustrated in the first graphic above, i.e. that overtraining gets you hurt. Hreljac made a point which was a bit more subtle: there are authors who suggest that things like high arches/flat arches/ overpronation/underpronation can make it more likely that an athlete will get hurt, but there is no consensus, because other studies have shown no relationship! In other words, we have no real way of looking at someone beforehand and saying, “you are going to get hurt because of 'X', so we need to get you orthoses/different shoes/a better diet” etc. We have no way of objectively deciding what will contribute to injury, and thus have no means of prevention. Except, of course, common sense. We'll get back to that in a minute.
As a physician who has had a couple overuse injuries, I cannot help but be partial in the biomechanical aspect of this. I feel it is certainly part of the story. My Achilles tendonitis was thought to be the result of overpronation and poor alignment, and it resolved shortly after I began using prescription orthoses in my shoes to correct these problems. (Minor point of medical-speak: Orthosis is the proper name for what most people call an 'orthotic'. An orthosis is made in an orthotic lab.) That being said, this tendonitis did not manifest itself until I began getting overaggressive in terms of how fast I was advancing my training program. As with most things in life, it probably isn’t a black and white issue. Your body may adapt to the stress of training and possibly your poor mechanics, and find a point of balance which will be lost if either changes dramatically, or too quickly for it to re-adapt. Also, remember again that you can get hurt with near perfect mechanics, it may just take you a bit longer.
If we believe that overuse injuries are the result of both overuse and possibly poor mechanics (and I dare say this is the opinion of most clinicians, if not researchers), we must consider whether or not it is possible or useful to attempt to alter mechanics in ways other than footwear. The literature shows this is indeed possible, however, the literature is pretty thin on whether it does any good. The literature also by and large indicates that athletes find their own most efficient gait. Is there something to be said for advice on running form from a good coach? Possibly. But that still falls squarely in the realm of coaching, and not science. It might be worthwhile in the face of recurrent injuries, but if you are currently running injury-free, I would be hard pressed to tell you to start messing around with the way you run.
Since the data may be lacking at the moment, science probably needs to be balanced with common sense at this time. I would suggest that you pay close attention to the periodization of your training program, since we know that a speedy overload will lead to speedy injury. Don’t just arbitrarily start training faster or longer. Changes must be gradual and advancement must come slowly. My own personal bias is that you should not advance your program until you have tapped out all advancement from your current level. If you are getting faster over time doing a particular track workout, keep doing it until you stop seeing improvement. Then you can make a gradual change, knowing that your body has fully adapted to the current stress and is ready for more. If you get to the point when your gradual increase pushes you into the red zone, it is time to see your friendly neighborhood doctor to figure out why, and what you can do to correct it.
As always, remember that your best results and state of health will be the direct result of how much you work the muscle between your ears. Keep training smart. In an upcoming article, we will talk a little bit more about periodization and how to it can help you stay strong, get stronger, and stay injury free.
References:
Hreljac, Alan. Impact and overuse injuries in runners. Med Sci Sports Exerc 36(5): 845-849.
