Loading of the Musculoskeletal System

Question 1

Define injury

Answer 1

Injury occurs when the load applied to a tissue exceeds its failure tolerance

Question 2

Two crucial factors in how and where injury occurs are?

Answer 2

1. The load
   (the sum of the forces and moments of force acting)
2. The characteristics
   (of the loaded structures)

Question 3

Define a chronic (overuse) injury

Answer 3

Results from repeated overloads with insufficient time for recovery.

Question 4

Define acute (traumatic) injury

Answer 4

Results from a single or a few repeated episodes

Question 5

What are the five different types of load?

Answer 5

1. Bending
2. Compressive
3. Tensile (Tension)
4. Torsion (Twisiting)
5. Shear (Opposite/broken leg in rugby)

Question 6

Five different load characteristics that are import in injury?

Answer 6

1. Type of load
2. Magnitude of load
3. Rate of load
4. Frequency of load
5. Strain

Question 7

Define strain?

Answer 7

Strain is a measure of how much a material is deformed

Strain is calculated as a percentage of change.

Question 8

Define Stress?

Answer 8

Stress is a measure of how much the material resists its deformation

Question 9

Define young’s modulus of elasticity

Answer 9

Also known as the elastic modulus, it is the ratio between stress and strain and measures the stiffness of the material.

Question 10

The three stages involved in the stretch-shortening cycle are?

Answer 10

1. Preload
2. Elastic energy storage
3. Reflex potentiation

(Example skipping)

Question 11

Define Resilience?

Answer 11

The amount of energy returned as a percentage of the amount of energy stored during deformation.

Energy losses occur in materials because some of the strain is not recoverable, and the combination of viscous and elastic components of biological materials therefore leads to a hysteresisloop.

Question 12

High passive stiffness of tendons means what four things?

Answer 12

1. Smaller pre-and braking phase muscle activation
2. Less tendon strain
3. Stiffer tendon and more efficient recoil
4. Less muscle activity (contraction) and thus more efficiency.

Question 13

Three training aims for better performing tendons?

Answer 13

1. Increase muscle-tendon stiffness
   (e. g., through plyometric training).
2. Develop muscle strength
   (not necessarily size).
3. Increase the cross-sectional area of important tendons
   (e. g., through strength training, endurance training)