In the world of athletics and pursuit of elite level performance, injuries are a given. However, the prevention of sports injuries is never as simple as identifying movements or exercises that should be avoided. It would be nice if it was that simple and if we could solve all the injury problems for athletes across the globe by eliminating one particular movement. Unfortunately, the human body is too complex to be solved by one solution that can be applied to everyone.
Rather than debate the role of specific exercises in a training or rehabilitation program, loading parameters and progressions, or whether certain exercises pose greater risk than reward, the purpose of this article is to discuss a much deeper concept that is at the heart of injury prevention and management, the balance between stress and adaptation.
Hello, My Name is Stress
Stress is something each and every one of us is all too familiar with. Whether it’s related to financial struggles, work-related problems, academic pressures, athletic expectations, family or relationship issues, stress is a common theme of the human existence. Now while these forms of mental stress are responsible for many reactions within the human body, for the purposes of this article this is not the kind of stress I am talking about. Rather, we will be discussing what is known as biological stress and how it relates to injury.
What is Biological Stress?
Biological stress accounts for all the physical demands (stress) placed on our bodies, both mechanical stress and metabolic stress.
Mechanical stress is a measure of the force produced and absorbed by the entire neuromusculoskeletal (NMS) system, including components such as nerves, muscle fibers, tendons, ligaments, fascia, and bone.
Metabolic stress is a measure of the demand placed on all the systems responsible for energy production/recovery and involves every major organ system in the body, such as the cardiovascular, nervous, muscular, endocrine, and immune systems.
As you can tell, both mechanical and metabolic stress are highly interrelated. The greater the degree of mechanical stress, the greater the degree of metabolic stress.
Balancing Stress & Adaptation
Training is best defined as, “the targeted application of stress designed to disrupt homeostasis and put the body’s defense mechanisms at work; remodeling, strengthening and improving the efficiency of many different systems throughout the body.”
Factors that Influence Biological Stress:
- Training Volume
- Training Intensity
- Training Frequency
- Exercise Selection
These simple variables are what define individual training sessions and the training block/phase. They will dictate the amount of biological (mechanical and metabolic) stress, its application to the human body, and how much stress is applied. The training goal becomes to apply the correct type of stress in the appropriate dose/amount while targeted to the appropriate areas necessary to improve performance.
Training and biological stress is one side of the coin. The other side takes into consideration factors that influence adaptation. What makes the training process enormously more complex than it appears is what happens in between sessions as our body responds to the stress of the training session or adapts. The complexity stems from how many variables are involved in how we adapt to the stress imposed by training.
Factors that Influence Adaptation:
- Training History
- Nutritional Habits
- Sleep Quality
- Mental Stress
Our genetics, nutritional habits, level of mental stress, training history, and sleep play a critical role in how quickly our body’s systems and tissues are able to rebuild and adapt from the stress of the training process. Get enough sleep, eat well, have better genetics and a long history of training, you will adapt much faster and respond quicker to the same level of training/stress than someone who is experiencing higher levels of mental stress, has poor sleeping habits, a poor diet, and lesser genetics. Even minor differences in any one of these factors can have a major impact on the ability to adapt to your current training.
Out of Balance, Out with Injury
By now, it should be clear that looking at sports injuries solely from the standpoint of the use or misuse of particular exercises or protocols doesn’t paint a very complete picture of why they happen. Even when discussions of injuries extend into the realm of assessing various movement patterns and joint function while trying to predict or minimize risk of injuries purely through improving quality of movement, often times these discussions fail to consider the fundamental concepts of the stress-adaptation balance.
The truth that is rarely discussed is that every athlete and individual is truly different and no two people will ever respond to a given training program or level of stress in the same manner. Recently, the days of individualized training
have been replaced with current fitness trends of bootcamps, CrossFit, P90x and other such programs that irrationally encourage anyone and everyone to do the same thing.
Not only do such approaches always fail to consider a person’s individual ability to adapt to stress, they often preach that results are a direct result of nothing more than lots of effort with lots of intensity. The classic American attitude of “more is always better” approach has spilled over into training, training with high intensities at increasingly higher volumes. Now combine that with no individualized considerations and what you have is a recipe for injury. Current fitness trends seem to place a greater importance on the business model rather than having an appreciation and understanding of the complex function of the human body as it relates to developing a quality training program for the individual.
When you consider the stress-adaptation balance, it's not surprising why the injury rates are continually rising in youth sports. Young athletes today are under incredible pressures to specialize in one sport, be it from coaches or parents, and this is why it’s become sadly common to see athletes as young as 12-14 suffering from chronic stress injuries like tendinitis, or the more correct diagnosis of tendinosis
. The ‘multi-sport’ athlete has been replaced with the ‘single-sport, all year long’ athlete. A year round competitive schedule, lack of properly constructed sport practice, and lack of time dedicated to physical preparation and athletic development is largely to blame for the huge increase in youth sports injuries in recent years.
I just happened to catch a recent interview with Tommy John on Dan Patrick’s radio show. For those of you who may be familiar with his name, Tommy John is a former MLB pitcher and the “Tommy John” surgery is named after him since he was the first individual to have the medical procedure of ulnar collateral ligament reconstruction. When asked about his thoughts as to why the surgery is so common now, Tommy John has this to say,
“I really believe….that sports, high school sports, little league sports, have become year round. And they force these kids at a very young age to pick a sport and that’s the only sport that they play, they train at. And you have these….pitching academies and your kid comes in and pays $2000-$3000 and you go in every Saturday and work on pitching. And I tell parents this, “If the best pitchers in the world don’t pitch year round, then why should your kid pitch year round?”….You have to get all these great surgeons that do Tommy John surgery, or did Tommy John surgery, they cringe when you say ‘year round pitching’ because you must let the arm rest.”
Without knowing exactly why, Tommy John nailed the central issue when it comes to several sports injuries, the lack of appropriate rest to allow the body the chance to recover and adapt to the stress placed upon it. Despite his example of baseball and pitching, the truth is each sport has it own unique injury rates. It truly all comes back to stress and the inability of most coaches and trainers to respect the stress and adaptation process. While some athletes are capable of adapting to stress far more efficiently than others, no one is immune from the effects of a poorly designed training or sport preparation program. Such programs are run by coaches or trainers that chronically stress athletes with little understanding of how to facilitate recovery and adaption, ultimately leading to injury.
Regardless of whether you are a doctor, therapist, coach, athlete or simply just train to be healthy and stay in shape, this article was to present you with a more complete view of the role stress and adaptation play in the injury process. There is certainly value in assessing the degree of stress specific exercises may place on particular joints/tissues and whether or not they are appropriate for an individual given their needs or limitations. Failure to consider the role of stress tends to lead to an approach to injury prevention based purely on exercise selection/avoidance rather than one than also places consideration on biological stress and adaptation management.
More related reading: