Both extrinsic and intrinsic factors can increase the risk of injury. Intrinsic factors include biomechanical deficiencies, including malignancy of limbs, muscular imbalances, degenerative processes, and other anatomical factors. Extrinsic factors include training errors, faulty technique, poor environmental conditions, incorrect equipment and surfaces. (Crown 1997).
Extrinsic Factors of injury can be further classified into overuse, misuse, abuse, or disuse (Wanivenhaus 2012).
- Overuse is performing a task with a frequency that does not allow the tissues to recover and symptoms may be due to lack of muscle strength or endurance
- Misuse using improper form or equipment which may put abnormal stress on tissue structures.
- Abuse is inflecting excessive force through normal tissues.
- Disuse occurs after taking a period of time off without training resulting in deconditioning or altered neuromuscular control
Excessive fatigue can negatively affect proper form and/or decreases the ability of stabilizers to maintain sound biomechanics. Careful monitoring of training volume, intensity, and duration will minimize overuse injuries. (Wanivenhaus 2012)
Intrinsic factors such as stability and mobility deficiencies have been attributed to athletic and fitness related injuries. Compensatory movement patterns develop to overcome stability and mobility deficiencies. These poor movement patterns are used subconsciously whenever executing future tasks leading to greater mobility and stability imbalances and deficiencies which increase risk of injury. (Cook 2010)
Prior injury is one of the the most significant risk factors predisposing individuals to injuries. A decrease in proprioceptive input occurs if an injury is left untreated or inappropriately treated. A disruption in proprioception will negatively affect movement-pattern behaviors. The altered mobility, stability, and asymmetric influences eventually lead to compensatory movement patterns, increasing risk of injury. (Cook 2010)
Risk of injury is increased under following conditions:
- Insufficient warm up
- Insufficient recovery
- Training stimulus is not progressive and regular
- Mechanical impairments
Also see first 4 of 5 Adaptation Criteria.
Biomechanical impairments, or deficiencies, may contribute to orthopedic injury when combined with other factors than may negatively affect joint integrity (e.g. hyper-mobility, biostructural weakness, insufficient adaptation of joint or muscular structures, fatigue, acute or chronic overtraining, etc.). For example, hypermobility does not produce joint instability unless the secondary stabilizers do not function adequately, and symptoms occur (Tovin 2008).
These biomechanical impairments are listed above for precautionary measures, so they may be identified and possibly corrected in attempt to decrease risk of athletic injuries during exercise or physical activity. A physician may need to establish if a biomechanical deficiency is structural, muscular, neuromuscular, or due to some other pathology.
These impairments are possible risk factors for injury and may only increase injury when combined with other risk factors. For example, although hypo- or hyper-flexibility may be a risk for injury, joint integrity and muscular strength may compensate for inflexibility. In a case with tight hamstring, the spine will likely need to articulate through a fuller range of motion to compensate for inflexibility through the hips. A program of low back strengthening exercises through a full range of motion has shown to cure chronic low back pain in most cases (Nelson 1995).
Following an orthopedic injury, restricting range of motion (i.e. splinting) to reduce risk of injury may be a short-term strategy to decrease further injury. However, when incorporated as a medium to long-term strategy, it may in fact increases the risk of the very injury in which the modification is intended to address. Immobilizing of a joint promotes deconditioning and consequently, deterioration of the joint structures. Injury may ensue when the joint is taken through a fuller range of motion in which it is accustomed to.
Supplemental flexibility exercises can be performed if full range of motion movements cannot be performed throughout the initiation of the rehab process. However, strength gains and joint integrity will not be fully potentiated throughout the avoided range of motion.
A more effective rehabilitation strategy would be to restore functionality to the afflicted joint while possibly increasing range of motion at the adjacent joint. Restoring functionality to the affected joint involves the initiation of range of motion exercises and then eventually incorporating progressive strengthening movements through a full range of motion. Increasing range of motion through the adjacent joint involves performing specific flexibility exercises and/or also including full range of motion strengthening movements for relevant muscles crossing the adjacent joint. For example, full range of motion weighted hyper-extension utilizing full range of motion to both spine and hips will strengthen the spine through a full range of motion while increase or maintaining range of motion through the hip.
The corrective exercises listed for each deficiency assume impairments are due to a muscular imbalance (flexibility, strength, or posture). Only a qualified physician or health care provider should diagnose and give prescription for an existing injury. In some circumstances, an attempt to correct a biomechanical impairment may irritate the injury and prolong recovery, particularly if certain therapy exercises are used inappropriately or initiated too soon or aggressively after an injury has occurred. The exercise selection should be based on positions that do not overstress the healing tissues. Even after an underlying biomechanical impairments have been improved, a preexisting injury may require the attention of a physical therapist under the advice of a physician to restore total functionality. See Injury Prevention Tidbits and Sports Injury First Aid.
In athletic conditioning, improper planning and inadequate conditioning (both general and sports specific) prior to the competitive season are major causes of injury. In elite athletes, high volume and intensity of the training load is one of the major causes of injury (Slobounov SM 2008). Also see Causes of Injury (above).
An improperly planned conditioning program can be attributed to failure to understand and implement fundamental training principles and adaptation criteria through a periodized programming. A program that does not adequately prepare the athlete for the specific types of forces and stresses experienced on the field or court place athletes at risk. See Training Specificity and Resistance Training for the Reduction of Sports Injury. Programs that fail to incorporate movements that condition stabilizing muscles (joint stabilizers such as hamstrings, rotator cuff muscles, etc), maintain ideal muscular balance, and correct biomechanical deficiencies unique to each athlete, increase the risk of injury on and off the playing field.
Contrary to popular belief, conventional stretching per se does not appear to decrease the occurrence of injury (see Stretching and Flexibility). However, movement specific warmups before drills, tests, and the event performance can decrease risk of injury. Ideally, movement specific warm-ups should proceed the event by several minutes, mimic the sports activity in the exact mechanics in which it will be performed, yet, not be so taxing as to compromise sports performance. Some sports are obviously more unpredictable than others and will not allow for rehearsal of every possible movement several minutes before they occur. Power or speed sports should consist a short series of movement specific warmups at progressive intensities. For example, several minutes before the start of 100m dash, a sprinter could perform a short progressive submax series of block starts immediately, followed by a short run, or simulated movement, thereby warming up in the same mechanics in which they will be engaging.
In the weight room, performing a movement specific warm-up set (eg: 50% 10RM) before workout sets, allow for performance benefits in addition to decreasing the risk of injury (see Weight Training Warm-up). Injuries can also be circumvented by well thought-out programs that adhere to evidence based research and sound training protocols (see Weight Training Periodizaiton) that allow for adequate recovery (see Overtraining). Also, using too much resistance or performing too many sets, particularly when athletes are first introduced to new movements or exercise variations are common training errors which can greatly increase the risk of injury.
The coach can introduce methods in which athletes can customized a 'group program' to each athlete's unique abilities, results, and needs. Coaches must allow for proper rehearsal and adaptation to 'new' exercises or movements, understand the benefits periodization techniques, adhere to adaptation criteria, implement program customization, use of movement specific -ups, and schedule adequate recovery periods for optimal progress.
Cook G (2010) Movement: Functional Movement Systems, pg 65-67.
Crown LA, Hizon JW, Rodney WM, (1997) Musculoskeletal Injuries in Sports, The Team Physician's Handbook, Mosby, 2: 361-370.
Nelson, B.W., O'Reilly, E., Miller, M., Hogan, M. Wegner, J.A., Kelly, C., (1995). The clinical effects of intensive, specific exercise on chronic low back pain: a controlled study of 895 consecutive patients with 1-year follow up. Orthopedics, 18(10), 971-981.
Slobounov SM (2008). Injuries in Athletics, Causes and Consequences, Springer, 25-43.
Tovin BJ (2006). Prevention and Treatment of Swimmer's Shoulder. North American Journal of Sports Physical Therapy, 1(4): 166-175.
Wanivenhaus F, Fox AJS, Chaudhury S, Rodeo SA (2012). Epidemiology of Injuries and Prevention Strategies in Competitive Swimmers. Sports Health. May 2012; 4(3): 246–251.