Causes of injury

· Injury risk is caused by a complex interaction of internal and external risk factors; avoid blaming injury on one factor only.
· Internal risk factors = individual variables that make a person more susceptible to injury.
· Key internal examples: age, sex differences, pregnancy, effects of training, congenital factors, and previous injury.
· External risk factors = environmental variables outside the individual.
· Key external example: personal protective equipment, including whether it is used, suitable, correctly fitted, and appropriate for the sport.
· Exam focus: explain how risk factors predispose an individual to injury before the injury-causing event occurs.

This diagram is useful for distinguishing internal and external causes of injury. It supports the IB idea that injury risk is multifactorial, not caused by one isolated variable. Source

Internal risk factors

· Age: affects tissue resilience, recovery rate, strength, balance, coordination, and injury vulnerability.
· Sex differences: may influence injury risk through anatomical, hormonal, strength, flexibility, and neuromuscular factors.
· Pregnancy: may alter balance, joint loading, centre of mass, ligament laxity, and exercise tolerance.
· Effects of training: training can reduce injury risk when appropriate, but poor training can increase risk through fatigue, overload, altered technique, or overtraining.
· Congenital factors: inherited or developmental anatomical features may affect movement patterns or tissue loading.
· Previous injury: a major risk factor because it may leave weakness, reduced range of motion, poor proprioception, or compensatory movement patterns.

External risk factors

· Personal protective equipment can reduce exposure to abnormal forces, but only if it is sport-specific, correctly fitted, and used consistently.
· External factors are considered environmental variables because they come from the sporting or exercise context.
· Examples to apply in answers: footwear, helmets, mouthguards, shin pads, bracing, playing surface, equipment design, rules, and contact with opponents or objects.
· Weak exam answers list factors; strong answers explain how the factor changes force, loading, stability, or movement control.

Acute trauma

· Acute trauma = injury caused by a sudden or excessive application of force.
· It may also occur when force comes from an unexpected direction.
· Examples: collision, fall, tackle, twist, landing awkwardly, or being struck by equipment/opponent.
· Acute trauma can damage connective tissue, muscle, bone, skin, and the brain.
· Typical acute injuries: sprain, strain, fracture, dislocation, contusion, laceration, or concussion-like injury.
· Exam phrase: acute injury usually has a clear incident and rapid onset.

Cumulative trauma

· Cumulative trauma = injury caused by the repeated application of force over time.
· It develops when tissues experience repeated loading faster than they can recover or adapt.
· It is strongly linked to repetitive movement, high training volume, poor recovery, and faulty technique.
· Common examples: stress fracture, tendinopathy, shin splints, bursitis, and chronic muscle or joint pain.
· Exam phrase: cumulative trauma involves repetitive microtrauma rather than one obvious event.

Tissues affected by trauma

· Connective tissue: ligaments, tendons, cartilage, fascia, and other support tissues may be stretched, torn, or overloaded.
· Muscle: may suffer strains, tears, cramps, contusions, or delayed pain from excessive loading.
· Bone: may suffer acute fractures from high force or stress fractures from repeated loading.
· Skin: may be damaged by cuts, abrasions, blisters, or impact wounds.
· Brain: only functional concussion-like injury is assessed in this subtopic.
· For brain injury, focus on function, symptoms, and mechanism rather than detailed brain anatomy.

Acute trauma vs cumulative trauma

· Acute trauma: one sudden event; force is large, unexpected, or applied in an unsafe direction.
· Cumulative trauma: repeated smaller forces; damage builds gradually through overuse.
· Acute example: ankle sprain from landing on another player’s foot.
· Cumulative example: stress fracture from repeated running load with insufficient recovery.
· Key comparison: acute = sudden macrotrauma; cumulative = repeated microtrauma.
· Both can be influenced by the same risk factors, such as previous injury, poor technique, fatigue, and equipment choices.

This page is useful for visualising how sports injuries can be classified by mechanism. It supports the IB distinction between sudden trauma and repeated microtrauma. Source

Exam application tips

· When asked for causes of injury, structure answers as risk factor → mechanism → tissue affected → injury outcome.
· Example: previous ankle sprain → reduced proprioception → unstable landing → ligament sprain.
· Example: poor running technique → repeated abnormal loading → tibial stress → stress fracture.
· Example: incorrect protective equipment → less force absorption → greater impact → tissue damage.
· Always distinguish between predisposing risk factors and the trauma mechanism that actually causes injury.