Biomechanical modelling

Question 1

What are 3 types of biomechanical model?

Answer 1

1. Point mass
2. Rigid body (e.g. javelin or body segment)
3. Musculoskeletal (series of linked body segments including muscles)

Question 2

What are 2 types of modelling performed (relating to both rigid body and musculoskeletal modelling)?

What are the relevant inputs and outputs of each?

Answer 2

Forward dynamic:
- input - kinetic data (forces/torques)
- output - kinematic data

Inverse dynamic:
- input - kinematic data (velocity/displacement)
- output - kinetic data

Question 3

What are 8 approaches to understanding injury mechanisms?

Answer 3

1. Video analysis
2. Motion analysis of non-injury situations
3. In vivo studies (strain and force measurements)
4. Injuries during biomechanical experiments
5. Cadaver and dummy studies
6. Mathematical modelling
7. Athlete interviews
8. Clinical studies (CT, MRI, arthroscopy)

Question 4

What is the definition of joint reaction force?

Answer 4

The reaction force of one (body) segment on another

Question 5

What can inverse dynamics be used to predict with regard to biomechanical modelling and what data is used as an input to the model?

Answer 5

Predict loading at the joint (joint reaction force)

Inputs - movement and anthropometric data

Question 6

What are the two components of joint reaction force?

Answer 6

Shear force

Compressive force

Question 7

What is the name for the model used in inverse dynamic biomechanical modelling?

Answer 7

Free body diagram

Question 8

What is the sign convention for the direction of forces used in a free body diagram?

Answer 8

Assume the moving limb is the x-axis:

Positive (up and to the right [DISTALLY and ANTERIORLY]

Negative (down and to the left) [PROXIMALLY AND POSTERIORLY]

Question 9

What is BSIP?

What does BSIP stand for?

Answer 9

Body segment inertial parameters

Key parameters used in biomechanics (not just inertia)

Question 10

Give an example of resistance force as might be seen in a biomechanical model

Answer 10

Reaction force acting on a leg pushing it down e.g. quad machine

Question 11

Why are mathematical models sometimes preferable to using human participants for answering a research question?

Answer 11

1. Health and safety reasons
2. Ethical reasons
3. Dependent variables cannot always be measured directly on human participants
4. Independent variable(s) cannot be controlled sufficiently with humans
5. Models enable a great number of trials to be run quickly
6. Using a model allows you to isolate the effect of an independent variable on a single dependent variable
7. A model can enable an optimum solution to be found.