Loading of the Musculoskeletal system Flashcards
List 7 Injury Factors.
- Load characteristics
- Material properties
- Genetics, Age, Gender
- Fitness level
- Skill level (training history)
- Fatigue
- Surfaces and Equipment used
Define Injury?
Injury occurs when the load applied to a tissue exceeds its failure tolerance.
Which two factors determine HOW and WHERE an injury occurs?
- The load, the sum of the forces and moments of force acting
- The characteristics of the structures being loaded
Define Chronic and Acute injuries?
Chronic injuries - results from repeated overloads with insufficient time for recovery
Acute injuries - Results from a single or a few repeated episodes
Which characteristics of load are important in terms of injury?
- Types of load (tensile, compressive, shear, bending, torsion).
- Magnitude of Load
- Rate of load applied
- Frequency of load repetition
What is the difference between stress and strain?
Strain - the amount of deformation that occurs following an applied load.
-Stress is the amount of resistance from the material to the deformation.
What is Young’s model of elasticity?
Also known as the elastic modulus, it’s a ratio between stress and strain. Young’s modulus measures the stiffness of the material.
What are the stages involved in the stretch-shortening cycle?
- Preload
- Elastic energy storage
- Reflex potentiation
SSC Summary Example…
An example of the SSC is seen when using a skipping rope. The eccentric contraction occurs upon landing, the calf muscles are stretched, and when they shorten it adds to the concentric contraction. Due to the elastic energy provided in this process, it is quite easy to skip for long periods of time without getting fatigued.
What is Hysteresis/Resilience?
The amount of energy returned as a percentage of the amount of energy stored during deformation.
What is a Hysteresis loop?
Within elastic components, the strain is recoverable BUT the stress-strain curve is not the same for loading and unloading. Such materials instead exhibit viscoelasticity, involving both elastic and viscous components. A hysteresis curve shows the energy absorbed during one loading-unloading phase.
What are the characteristics of a ‘better performing tendon’?
- Higher passive stiffness of tendons
- Smaller pre-and braking phase muscle activation
- Less tendon strain
- Stiffer tendon and more efficient recoil
How would you adapt training for ‘better performing tendons’?
- Increase muscle-tendon stiffness (through plyometric training)
- Develop muscle strength (not necessarily size)
- Increase the cross-sectional area of important tendons (strength training, endurance training) and thus reduce risk of injury.
