L24, Role of Movement Variability

Question 1

Objectives:

• To understand different forms of movement variability
• To understand the importance of variability in human movement
• To view variability across tasks, expertise and body segments

Answer 1

Summary:

• Variability in what? End-point or coordinative elements?
• Three main roles: Adaptability to new situations; reduce repetitive load; identify and transition from unstable movements
• Certain elements can compensate for others being ‘out of position’- termed synergies

Question 2

What is variability?

Answer 2

• Difference in technique or performance over several repetitions

Question 3

What is end-point variability? Give 3 examples:

Answer 3

1. Variability in the trajectory of the end-point in the kinetic chain
2. Stride length, stride time, ball release angle

Question 4

What is coordination variability? Give 3 examples:

Answer 4

1. Variability in the relation between segments controlling the end-point
2. Knee angle, hip-knee coupling, segmental force contributions

Question 5

What is meant by ‘funnelling’ of variability?

Answer 5

End-point and coordination variability change throughout the movement, tends to funnel (decrease) towards the end of movement.

Question 6

What are 3 possible roles of variability?

Answer 6

1. To provide flexibility and adaptability in new and varying environments
2. To reduce repetitive tissue loading
3. Initiating the transition from one stable mode of coordination to another

Question 7

Give 3 examples of variability from this lecture:

Answer 7

1. Expert vs novice pistol shooters, experts more accurate and kept pistol barrel more stable but showed more variability in shoulder, elbow and wrist.
2. Divers not allowed to balk in competition but can in training, intervention introduced to reduce balking in training. Average score improved post-training, mainly due to poor dives improving.
3. Healthy runners showed more variability than runners with Patellofemoral pain (PFP). “Looser coupling between hip and knee for healthy individual

Question 8

Infants with delayed development have…?

Answer 8

More rigid, less variable movement

Question 9

What is meant by synergies?

Answer 9

‘Variables’ can work together. If one variable produces error, the others can minimise the error

(A good reason not to treat variables independently)