Biomechanics of injury and injury prevention

Question 1

• List the three stages in the biomechanical reduction of injury process.

Answer 1

1) DESCRIPTION OF INCIDENCE AND TYPES OF INJURY
2) IDENTIFICATION OF FACTORS AND MECHANISMS OF INJURIES
2) Prevention and reduction of risks

Question 2

• Describe the process involved in stage 1 – Description of incidence and types of injury.

Answer 2

This stage involves identification of injuries
- Statistics on injury rates and types
- Analysis of Single / individual injury

Question 3

• Describe the process involved in stage 2 – Identification of factors and mechanisms of injury.

Answer 3

This stage involves
- Properties of biological materials (estimation of forces)
- Mechanisms of injury occurrence

Question 4

Complete this sentence: Injury occurs when ….

Answer 4

loads exceed tissue failure tolerance

Question 5

• There are six main contributory factors that injury occurrence and type in sport / exercise / work depend upon. List, explain and provide examples for each of these six factors.

Answer 5

Load characteristics
- Type (tension, compression, shearing, etc)
- Magnitude
- Load rate
- Frequency of load repetition

Characteristics of loaded tissues
- Material properties of bones & soft tissues
- Structural properties of bones, joints & soft tissue

Genetic factors
- Innate musculoskeletal deformities
- E.g. Flat feet, leg length differences (adds curve in leg forces, not simply compression –> increased injury)
- Age, sex

Fitness or training status
- Lack of flexibility or joint laxity
- Muscle strength imbalances
- Incorrect body weight
- Excessive training load for fitness state
- Overtraining, fatigue

Technique
- poor technique causing excessive loads
- illegal technique

Equipment and surfaces
- Human surface interface
- Human and equipment interface

Question 6

• The prevention and reduction of risk stage involves the application of knowledge obtained from the earlier stages and can result in what? Provide at least one example for each.

Answer 6

• Rule changes (games rules change for safety)
• Equipment modification (safer, more protective equipment)
• Technique modification (safer movement for performing skill)
• Physiological adaptation, physical fitness and conditioning of the athlete
  - muscle strength limitations, fatigue, etc

Question 7

• The type of surface and properties of these surfaces greatly influence injury risk and rates. List and explain how 5 different surface properties can influence injury rates.

Answer 7

Friction and traction
- Too high and too low

Compliance
- Amount of deformation under load
- Too high and too low

Rebound (resilience)
- Measure of energy absorbed by the surface that is returned to the striking object
- Lack of resilience causes fatigue

Hardness
- The resistance of a materials surface layer to penetration

Force reduction
- Expresses the % reduction of max force experienced on a surface compared to concrete
- Impact attenuation
- IAAF specifies force reduction between 35 & 50%

Question 8

How might a surface that is too hard affect injury rates?

Answer 8

• Increase impact loading
  - Peak force, time to peak, RFD
  - Implicated with cartilage and bone damage (shin splints)
  - Increased incidence of tendon and calf injuries
  - Worst for lower limb and back injury
  - Klauss (1982)
  - Bone micro-fractures, pain and reduction in shock-absorbency, increased reliance on cartilage

Question 9

• Describe how uphill and downhill running can increase the risk of injury.

Answer 9

• Increased stress on patellar ligament and quadriceps tendon
• Increased stress on ankle plantar flexors
• Forward pelvic tilt and limited hip flexion increases stress on muscles of lumbar spine

Question 10

• Running shoes have been shown to affect injury rates in runners. Comment on the aspects of friction, impact and rear foot motion control in relation to running shoes.

Answer 10

Too much friction
- Insufficient rotational freedom between shoe and surface
- Foot becomes fixed and body rotates (knee Injuries)
- Ankle injuries in basketball and tennis
- Wet muddy fields may prevent boot studs from becoming stuck

Too little friction
- Slipping ➔ loss of balance ➔ muscle tears

Prevent over pronation of foot which can cause
- Causes increased medial rotation of tibia
- Linked with a wide range of injuries
- Can be caused by inappropriate heel flare
- Straight last helps reduce pronation