There is only one surefire way to prevent injuries. Avoid all physical activity.
Please don’t do that.
Contrary to popular belief, injury prevention is not simple. We cannot focus on a single contributing factor, such as mobility. Stretching will not prevent injuries. Specific equipment and playing surfaces will not prevent injuries. Even certain exercises and movement patterns commonly thought of as injury-inducing fail to hold water when facing the scrutiny of rigorous research:
- Lifting with a rounded low back does not cause injuries or maintain low back pain.
- Throwing curveballs is not leading to UCL tears and Tommy John surgeries in youth baseball players.
- Knees caving in when landing from a jump and hip weakness are not the culprits for ACL tears.
Don’t believe me about these claims? You are not alone. As a physical therapist, I frequently discuss these common misconceptions with patients, coaches, and other healthcare providers. I was even taught several prevention techniques in school and courses that are outdated and do not follow the research. Anecdotal experience and confirmation biases are strong.
When comparing controlled trials and objective research to subjective experiences laden with bias, the research always wins.
So what are the best methods for reducing injuries? What are the risk factors we should be concerned about?
Using exercise to prevent exercise injuries
When assessing the body of research as a whole, it appears multi-modal warm-up programs, like the 11+ or FIFA 11 program, are among the best short-term strategies for the prevention of injuries, such as ACL tears. (source) Warm-ups should focus on strength, power, endurance, and balance (not stretching). (source) Additionally, appropriate off-season conditioning and load management appear vital as well.
A 2014 study in the British Journal of Sports Medicine assessed the effectiveness of exercise interventions to prevent sports injuries. They concluded the following:
In general, physical activity was shown to effectively reduce sports injuries. Stretching proved no beneficial effect, whereas multiple exposure programs, proprioception training, and strength training, in that order, showed a tendency towards an increasing effect. Strength training reduced sports injuries to less than one-third. We advocate that multiple exposure interventions should be constructed on the basis of well-proven single exposures and that further research into single exposures, particularly strength training, remains crucial. Both acute and overuse injuries could be significantly reduced, overuse injuries by almost a half. Apart from a few outlying studies, consistently favorable estimates were obtained for all injury prevention measures except for stretching.
Injury prevention models have evolved over the past few decades. A consistent theme is load management. One of the most frequently cited articles in the field of injury prevention is the 1992 Sports Medicine paper “Incidence, severity, etiology and prevention of sports injuries.” van Mechelen proposes any injury prevention effort should follow four sequential steps:
- Establish the extent of the sports injury problem
- Establish the etiology and mechanism of sports injury
- Introduce preventive measures
- Assess the effectiveness of these preventive measures by repeating step 1.
There are three areas that must be addressed when determining the risk of injury: the stress capacity of an individual (assessing both internal and external factors), physical and psychosocial factors, and stress-strain capacity (specifically addressing the influence of chronicity)
Meeuwisse proposed an updated model two years later. You can start to see the difficulty of isolating causes of injuries and developing injury prevention strategies.
Source: Meeuwisse (1994) Figure 2.
Layering in supervision and coaching
A 2005 study expanded on previous models to include supervision and coaching. Why does this matter? Supervision and coaching influence the effort and duration of an activity.
An athlete's motivation, perception, and fatigue are all factors contributing to performance and risk for injury. In pitching, for example, fatigue is one of the greatest risk factors for injury. (source) The danger of relying solely on pitch counts and innings limits is the potential for an athlete to throw too much. Often, the athlete shows signs of fatigue and diminished performance before an objective threshold (e.g. pitch count) is met. It is up to the coach to determine if the athlete should be removed. Do they watch for signs of fatigue (ball control and velocity) or simply look at the pitch count?
If an athlete is performing in a game or fighting for a position in the starting lineup, it is more likely they will ignore the warning signs our body gives. They will push through fatigue, ignore pains, and push their body to the limit. While this can enhance performance, it can also lead to injury.
Source: McIntosh (2005) Figure 1
Moving away from a heavy focus on biomechanics
Aside from coaching and supervision, the McIntosh paper has a heavy focus on biomechanics and tissue failure. McIntosh proposes the most effective method to prevent injuries is by either reducing load on the tissue or increasing tissue tolerance (i.e building strength and endurance). This approach ties in the importance of biomechanics, movement, and form into conditioning programs. A biomechanical focus is certainly better than assessing a single risk factor, such as knee valgus, but it is incomplete. We still need to consider psychosocial influences. Bahr and Krosshaug did just that.
In the paper“Understanding injury mechanisms: a key component of preventing injuries in sport, ” the authors show how risk factors build on one another. A single risk factor is never the issue.
The challenge for athletes, coaches, athletic trainers, and physical therapists is to know which factors to prioritize. What are the internal risk factors to address first? Which are modifiable and how long will it take? Which are non-modifiable and need to be noted and worked around?
These questions are further accentuated in Bittencourt’s paper “Complex systems approach for sports injuries: moving from risk factor identification to injury pattern recognition — narrative review and new concept.” The authors implore athletes, clinicians, and researchers to abandon the risk factors in isolation approach and instead, understand the interaction between the risk factors.
Take into consideration the environment
The training load is influenced by the demand of coaches, the level of competition, the type of event (practice versus playoff game), and the period of a game (beginning when fresh versus the end when fatigued). Simply assessing single-leg squat performance and landing mechanics is not enough, nor should it be the main focus. Bittencourt summarizes this concept with the following:
Regarding sports injuries, the athlete should be analyzed as a complex system and the research focus would be on how relationships between units (i.e. biomechanical, behavioral, physiological and psychological) give rise to the collective behavior of the athlete and how the athlete interacts and forms stable relationships (regularities) with his/her environment.
Athletes often push themselves more physically, mentally, and emotionally when in the heat of the competition. All of these variables add to the risk of injury. While impossible to completely replicate all these in the weight room and on the practice field, athletes can build off the traditionally prescribed exercises. The trick, however, is being able to address as many potential factors as possible, yet focusing on the most likely to cause injury.
Sport Specific Approach
The following graphic illustrates the complex web of risk factors for a basketball player and ballet dancer suffering an ACL injury. The primary clinical risk factors are bolded but the modifying factors are connected. When designing a rehabilitation and training program, athletes, coaches, trainers, and physical therapists must consider all the potential variables that can cause the observed risk factor. Dynamic knee valgus (knee crashing in) can certainly be addressed with hip strengthening and motor control, but if training is only performed in a controlled environment with minimal fatigue, the performance will quickly deteriorate in a practice or game.
Source: Bittencourt (2015) Figure 2.
At the end of the day, no single factor is responsible for injury prevention or appropriate return to sport. Relying on one measure will immediately set us up for a losing battle. Instead, athletes must know the specific demands of the activity that has led to an injury and future activities you want to perform.
Here is a list of recommendations based on current research:
- Complete dynamic, sport-specific movements consisting of power movements (rapid-paced) prior to competition or training
- Understand your body’s limitations
- Train at the same intensity as games
- Build up reserves of strength, power, and endurance beyond what is needed for a game
- Consider training load and design structured training program (periodization with specific rest)
- Don’t discredit the value of rest and recovery, understand the value of building strength and endurance, and recognize our bodies are resilient.
Each athlete is unique and will need to create a personalized approach with details that match their body’s, sport, and training history. Following these recommendations will not prevent injuries — no strategies can fully prevent injuries other than avoiding the activity altogether — but they will reduce risk.