Why Do Injuries Occur?
Overview
The question of why injuries occur might seem like an obvious one; an area of the body is subjected to a large or series of smaller repetitive forces, and the tissues and structures ultimately give way suddenly or over time. This narrative would explain injuries like broken bones during sports, an ACL tear, etc. On the other end of the spectrum, it would explain overuse injuries such as stress fractures, “tendonitis”, and shoulder “impingement.”
What some fail to recognize, however, is the significance of the various constraints aside from the environment or the task at hand which increase one’s susceptibility to sudden and overuse injuries. In this blog, I will be illustrating how personal constraints; such as physical capabilities, training history, anatomy and physiology, mindset, and rest; can interact with environmental constraints to impact an athlete’s injury type, risk, and severity.
Exhaustion and efficiency: is my body doing what I want it to do?
In an ideal training or competition scenario, an athlete’s movement output should coincide with the external demands of the environment, meaning the demands of the sport, environment, rules, competition, etc. Using soccer as an example, the athlete should be able to consistently match the external demands of the sport, whether that be the need to jog, sprint, kick a ball, change directions rapidly, and “improvise” based on the actions of the team and competition. This requires the athlete to be able to move and use his or her energy efficiently, as well as possess a spectrum of movement “options” at their disposal in order to react adequately to the changing demands of the game and the environment. This applies to any athletic activity, from soccer to CrossFit to crew; the athlete must be physically up to the task and also resilient enough to adjust to often-changing external demands.
As the external variables of athletics frequently change, so can the internal variables of the athlete, specifically fatigue. When fatigue progresses to a significant degree, the athlete’s ability to keep up with the external demands of the sport or task can be negatively impacted. Movement efficiency decreases, coordination or motor control can be impaired, and the athlete’s repertoire of movement options (or “adaptability”) shrinks. In these situations, rarely do the external requirements of the sport or task change; what changes is the athlete’s ability to meet those requirements. As conditions progress in this direction, the likelihood of injury can increase. This can be in the form of a traumatic “macroinjury,” when the athlete loses the ability to adjust properly within a small time frame (ie. an ACL tear), or an overuse “microinjury” when the external demands exceed the athlete’s physical ability to match those demands over longer periods time (ie. tendonopathy or muscular discomfort) .
Personal vs Environmental Constraints
The personal constraints that contribute to injury risk can extend beyond exhaustion, however, and can vary based on timescale, environmental demands, and the task at hand, as illustrated in the figure below.
For example, in a fraction of a second, a soccer player’s injury risk can be impacted by ball position, the spectrum of actions one can take in relation to pursuing the ball, and the athlete’s physical ability to change directions quickly to get to the ball. If the athlete either miscalculates, makes the wrong move, or doesn’t possess the physical ability to execute their intended movement, they may end up with a torn ACL or sprained ankle. Over the course of several days, an athlete’s injury risk can be impacted by their motivation to adhere to training (training too hard or taking too much time off), social pressure which can interfere with training, and workload specificity such as training a specific energy system or movement too much or too little prior to an event. In the timescale of several months, conversely, one can encounter the repercussions of overtraining syndrome or undertraining, which can in turn be impacted by seasonal variables as well as task-specific variables such as an athlete’s calendar of competitions, which are out of the athlete’s control to a degree. The latter two variables can influence and be influenced by an athlete’s preparedness over time, ultimately contributing to injury risk as well. What we can take away from this interaction between variables at different timescales is that athletes must be physically, mentally, and organizationally prepared for the myriad of factors outside of their control.
The Cell and Sport Connection
To properly illustrate how personal and task-specific variables can interact with tissue injury and vice versa, it can help to break things down to the involved systems, from the atom to the tissue to the task at hand. The figure below breaks down these levels in a visual format, starting from the smallest scale imaginable (the atom), going all the way up to the athlete, environment, and task at hand.
Without going too into the weeds, the most important takeaway here is that these various systems impact each other in both directions, meaning the person, task, or environment can have an impact on the cellular level and vice versa in situations where injury is possible or present. In strength training, for example, the athlete’s participation in training leads directly to temporary systemic stress, tissue breakdown, and cellular changes. Ideally, this process follows the Goldilocks Principle of being “just the right” amount of physiologic stress and results in positive adaptations from the cellular level on up, resulting in positive adaptations at the tissue and system level, and a net improvement in the athlete’s training goals. When the balance shifts in either direction, however, the result is either undertraining; an insufficient stimulus at the task level resulting in inadequate adaptation at the systemic, tissue, and cellular levels; or arguably worse, overtraining, where the stimulus is too significant or too frequent so that the systemic, tissue, and cellular systems are not capable of compensating for the global stimulus of training, leading to illness at the systemic level, injury and damage at the tissue level, and disorganization and improper turnover at the cellular level.
In the opposite direction, when the atomic, cellular, and tissue levels are disrupted through overtraining or undertraining, the result could go one of two ways for the athlete on a greater scale. These microscopic disruptions can be diffuse enough that the athlete’s subconscious adjustments are minute and go unnoticed. Conversely, these disruptions can become significant or localized enough that an athlete’s motor patterns may begin to change in subtle or noticeable ways to avoid pain or injury. These changes in movement and coordination can begin to restrict the athlete’s movement options and resilience in the task at hand, and ultimately can lead to an increased risk of injury because the athlete is not equipped with enough movement options in order to adapt to the athletic task at hand. This can largely explain why many common injuries such as ACL or muscular tears occur, and why more freak incidents occur such as weightlifters dislocating an elbow while receiving a snatch.
Conclusion
While the myriad of factors that contribute to injury risk may seem daunting, a takeaway for athletes should be that injury risk reduction goes beyond just staying flexible or strong. Athletes must be adept in multiple categories; including coordination, movement capabilities, endurance, focus, attitude, and training habits; in order to become resilient and adaptable in their sport. Building resilience is an ongoing campaign, not a destination. In order to be better athletes, we must be better humans and approach our craft holistically and comprehensively.
Dr. Brooks Kenderdine
Co-owner, PT, DPT, CSCS, USAW-1
The PATH Rehab & Performance
References
Pol R, Hristovski R, Medina D, Balague N. From microscopic to macroscopic sports injuries. Applying the complex dynamic systems approach to sports medicine: a narrative review. Br J Sports Med. 2019 Oct;53(19):1214-1220. doi: 10.1136/bjsports-2016-097395. Epub 2018 Apr 19. PMID: 29674346.
