L6, Biomechanical Principles Flashcards
Objectives:
- To become aware of biomechanical principles universal to all sports movements
- To understand importance of biomechanical principles in technique analysis
- To observe these principles to various movements
Practical thoughts:
- These principles are interconnected (e.g., reducing redundant DoF may also minimise energy use)
- Easy enough to target in video analysis for all movements
- Consider these principles for all movements
- Prioritise on case by case basis (consider the task demands, but also the strengths and weaknesses of the athlete)
What is the stretch shortening cycle in biomechanical terms?
- Proximal segment rotates while distal lags
- Muscle crossing the joint is stretched then forcefully contracted
What are the 3 biomechanical mechanisms of the stretch shortening cycle?
- Increase ROM (Incr. distance over which distal segment can be accelerated, work, energy that can be transferred to end of limb)
- Enables concentric contraction phase to begin with greater force (f.v relationship)
- Trigger stretch reflex (Incr. neural activity to initiate contraction, stronger response if muscle is stretched quickly)
What is energy minimisation?
Perform movement effectively while doing less (unnecessary work)
What are 4 ways of minimising energy expenditure?
- Rely on passive tension (i.e., SSC)
- Rely on gravity as a force
- Rely on sequencing
- Simplify movement
What is meant by controlling redundant degrees of freedom?
- DoF in our bodies are far greater than the environment
- Equivalent outcomes can come from different movement patterns
- Movements with substantial out-of-plane motion difficult to achieve consistency
Give an example of controlling redundant degrees of freedom:
Throwing darts with only the elbow bending means there are no degrees of freedom during the downward movement of the elbow. Involving the wrist in the movement allows for a degree of freedom.
