Friday, January 02, 2009

Preventing Injuries: Biological Robustness

Preventing Injuries: Biological Robustness

I'm a risk averse type, who happens to enjoy some slighly risky activities, so I've always had an interest in injury prevention. In the past decade I've gotten more systematic about preventing injuries. A minor pull that would have taken a few days to heal in my teens will now at 50 sideline me for weeks or even months. And after a few weeks off, I'm pretty much starting over on some aspects of my training. Rather than challenge my motivation to keep starting over and over, I've learned to greatly reduce my injury rate with a judicious little bit of extra training. If you just want to cut to the chase, you can skip down to the last couple of sections. If you want to know the background of the robustness approach , which I think is pretty interesting, then read on.

The biological robustness approach to injury prevention

The concept behind injury prevention that I've adopted is called biological robustness. Biological robustness is based on a adaptive systems approach to human movement. The essential idea is that biological systems preserve their integrity and their core functions in spite of both internal and external perturbation, and we can make use of that fact to understand how things go wrong and make ourselves more resistant tp injury.

How the Body Responds to Stresses: Claude Bernard and the Inner Steady State

The central theme of biological robustness originated in the concept of homeostasis.

Homeostasis has a notable pedigree in physiology, going back to the man often considered the father of modern physiology in the mid 19th century, Claude Bernard. Bernard coined the term "mileu interior" for the internal environment of living things. He wrote that "La fixité du milieu intérieur est la condition d'une vie libre et indépendante" which means:

The constancy of the internal environment is the condition for a free and independent life.

Maintaining the Internal Steady State: Extended to a General Principle

This idea was later developed by physiologist Walter Cannon in the early 20th century into the concept of homeostasis. Canon published his ideas in 1932 in The Wisdom of the Body.

Most important for our purposes, Cannon reasoned that homeostasis does not occur by chance, but is the result of organized self-government. This is a very significant observation and modern biology has recently begun to build on it increasingly to see the body in terms of more tightly interconnected systems rather than a collections of loosely coordinated individual parts.

This probably seemed to a lot of mechanically minded physiologists at the time as a rather unlikely or even an unscientific notion. Fortunately our increasing understanding of how complex systems work in general has made Canon's ideas increasingly plausible and important over time rather than relegating them to the science museum with phlogiston and luminiferous ether.

Biological Stress Challenges Our Integrity

Canon's homeostasis, derived from Bernard's mileu interior, became the foundation for the familiar notion of stress, first discussed in this context by endocrinologist Hans Selye in the 1930's. Canon was the one who first coined the popular expression "fight or flight response" in 1915 and it later figured importantly in Selye's concept of stress, along with the idea of homeostasis.

Biological stress is when our capacity to maintain our internal steady state environment is exceeded, whether it is because of real external threats or even perceived ones (which is why there are psychological components to stress as well as physical components).

In the process of preparing for and responding to threat, organisms bring all sorts of emergency mechanisms into play. Selye theorized that when stresses were extended too long, these emergency responses would eventually become exhausted, leading to illness and injury. Other theorists since then have proposed the alternate theory that stress-related illness results not so much from the exhaustion of the emergency mechanisms as from their effect itself on our tissues and organs over time.

In either case, the significance to us is the same: extended stressors without relief lead to breakdown. That becomes the model for how chronic injury occurs. It is also potentially an important factor even in acute injuries, which often occur when we are fatigued or distracted, both of which are sometimes related to the effect of stressors.

Homeostasis Expands To Biological Robustness

The modern slant on Selye's idea that makes it much more useful for injury prevention is that we have extended the mileu interior to a systems model of how the body operates in general, not just how the body regulates some of its interior processes. Biological robustness means the ability of the body to maintain its core functions in spite of unexpected events.

Note how much more general this is than Canon's homeostasis. The unexpected events might be inside our own body or things happening to us from the outside and they may be in many different kinds of systems. In a wide variety of cases our body strives to maintain function by adapting . Bernard's and Canon's careful observations about specific physiological processes turned out to be applicable to more systems than they first noticed.

This striving to adapt is important for a number of reasons. For example, it can mean that we will change our movement form (often without realizing it) to compensate for a stiffness or weakness in one muscle group by using other muscle groups differently. The fact that our body centrally coordinates movement as well as internal homeostasis means that problems in one place can end up being referred someplace else, a well known principle in modern physiotherapy.

It may seem obvious that when your left foot is hurt, you limp on it and change your gait to adapt, but the concept has some much more subtle implications. A tight iliopsoas muscle in the front of the hip can have an effect on how you use your gluteus muscles, which in turn helps cause an injury somewhere else. And this is a relatively simple and straightforward example.

What this all means to us for preventing injury is that we can't understand the mechanics of our activities just by studying human activity and trying to figure out where the direct physical stresses on us might be. We have to understand the patterns by which our body coordinates movement and strives to adapt to unexpected stresses.

How specifically does this translate to injury prevention? Expecting the Unexpected

Physical training for performance is mostly about identifying specific requirements and training in a way customized for those specific requirements. The better we know the demands of the activity, the better we can tailor the activities and schedules to meet them. Training is specific.

The way that biological robustness affects training is that we also have to take into consideration unexpected stressors as well as expected and well known ones. The principle of robustness training is "expect the unexpected." How the heck do you do that? It's not as crazy an idea as it first sounds. Although we obviously can't prepare for anything that might happen to us, there are a range of potential unexpected stresses that are found in any given kind of activity. For example, a runner can expect to sometimes hit broken ground and turn their foot over, a wrestler can expect to sometimes have body parts pulled forcefully to the limits of movement in various directions, and so on.

So knowing these potental unexpected stresses, how do you protect yourself?

Performance training and robustness have a critical tradeoff. The more you work to prepare yourself for specific expected demands, the more vulnerable you become to unexpected ones. It isn't obvious why this should be so. What seems to happen is that all this complex adaptation your body is doing to specific training demands leaves imbalances and vulnerabilities in other areas. As you become able to push more weight in one exercise, you may be developing a weakness somewhere else that is compensating for some minor internal or external factor that you don't even know about. Over time, even relatively minor unexpected stresses can hit one of these vulnerabilities, and all of a sudden we are injured and we don't know why. We assume we just worked to hard perhaps. But in some cases it was a long developing adaptation process.

How do we minimize the risk of this happening to us?

For each specific training goal, there is a related robustness goal.

When you train for strength, you are working to improve the work capacity of specific muscles and muscle groups. When you train for strength robustness, you look to increase modularity. This means looking at the chain of movements involved and enhancing the ability to withstand stress in each part of the chain. Rather than trying to increase the amount of weight you can push or pull, when you do strength robustness work you try to expose yourself to a wider variety of stresses on the various segments of the movement. You do simple assessment tests to find basic movement weaknesses and you address those. These often reveal problems that you never knew you had because your body found ways to compensate very effectively. But that compensation had an effect elsewhere over time and made you more fragile to injury from some unexpected small stressor.

When you train for general conditioning, you are trying to increase the capacity and efficiency of your cells and tissues to utilize oxygen and utilize various energy systems for movement. When you are trying to improve conditioning robustness you are instead trying to reduce fragility by preparing for a wider range of lesser unexpected challenges rather than a greater amount of an expected challenge. You subject yourself to a wider variety of moderate stresses, particularly varying resistance levels, range of movement around joints, and multidirectional patterns of movement. You want to constantly vary the stresses from session to session and from week to week to expose you to a wider variety of stresses than you would normally get in your activity, but which you still could potentially experience.

When you train for coordination in your activity, you learn movement skills for specific kinds of responses. When you are trying to improve coordination robustness you are looking to train your nervous system to adapt to unexpected variations in movement in your activity. This is done by focusing more deliberately on the skills involved in your training while you vary it. Rather than always turning your thoughts off and running on automatic in your conditioning sessions, you focus more on the skills you are using and vary the sessions, so you can teach yourself to perform the movements in different ways with skill. If you're a runner for example, you might deliberately extend or shorten your gait for a while, concentrating on otherwise maintaining good form. You don't want to do too much of this. You aren't trying to change your gait, you're trying to teach yourself to adapt to unexpected variations in movement. In general you might try varying the speed, direction, range, or rhythm of various movements in your activity.

Finally, consider the psychological dimension of stress. Deliberately focus on small easily neglected aspects of your training to look for problems and help recognize areas where you are frustrated or not in control. Use drills to help develop a greater sense of control over your performance. If you identify specific situations that cause you problems, expose yourself to them in a controlled way in practice to help desensitize yourself to it. Simulate problem situations and rehearse the coping skills you will need in realistic simulations.


Beginners often get too excited and simply overreach themselves. Aside from that, most injuries result not from doing too much or training with too high an intensity level, but from increasing difficulty too quickly without preparing properly or without realizing that there is a basic movement problem being compensated for. Using a conservative progression scheme and incorporating basic assessment tests goes a long way to preventing injuries.

If you want to do even more, then find subtle variations of your training methods that impose a wider variety of moderate stresses on your body, both slight variations in functional movements and in the individual segments of movement chains, and teach your body deliberately to adapt to
variations of stresses. Don't overdo this, it isn't meant to change your basic training program or interfere with it, it is meant to expand it at the boundaries to make you better prepared for the unexpected stressors that you will eventually meet.

Much thanks to Matt Lancaster for the ideas in his article Taking a robust approach to running from P2P Publishing (2008) from which a lot of the specific ideas in the last half of this post were taken. The Peak Performance web site offers a number of good articles and books that are well researched, authoritative, and practical.

No comments:

Post a Comment