Flashcards in Loading of the Musculoskeletal System Deck (21):
What is Injury
When the load applied to a tissue exceeds its failure tolerance
What are the two crucial factors in Injury?
Characteristics of Load Structures
What are the 4 things we cannot change?
What are the 3 things we can attempt to change?
Age, Gender, Surfaces, Load
Fatigue, Skill, Fitness Levels
What are the 3 types of injury?
1) Chronic - repeated overloads without recovery
2) Acute - single/few repeated episodes
3) Overtraining - result in injury - psychological
What are the 4 different load characteristics?
Type of Load, Load Magnitude, Load Rate, Frequency
What are the 5 types of load?
Tension, Compression, Torsion, Bending, Shear
What is load magnitude?
how much of the load occurs
What is load rate?
rate of change of force over time (f/t)
What is load frequency?
How it affects overuse injury - load reps and reps
What is the difference between stress and strain?
Stress - how much resists the change
Strain - amount of deformation that arises from an applied load
What are the variables measured in the stress-strain relationship?
How much is 100N/cm2 in Megapascals?
Strain = % of change
Stress = load per unit of CSA - N/cm2
What is Young's Modulus of Elasticity?
The ratio between stress and strain - measures stiffness of the joint
What is the difference in young's modulus between a spanner and a Theraband?
Spanner has high young's modulus = high strain
Theraband has low young's modulus = low strain
On the graph what define A, B and C and ER, PR and HR?
A = proportional limit
B = elastic limit
C = failure point
ER = elastic range (where it can go back to normal)
PR = plastic range (cannot return to normal)
HR = Hookean Region (where elastic body is deformed)
What is the relationship between muscle stiffness and the stretch shortening cycle?
What are the stages of the SSC?
eccentric activity enhances force production in the proceeding activity = increases stiffness
Preload --> Elastic energy stored --> reflex potential
What happens to muscle stiffness when you grow older?
Muscle stiffness increases and is therefore more resistant to change
What is resilience?
If a tennis ball has 50% resilience, how high will it bounce back up if dropped from a metre?
amount of energy returned as a % of the amount of energy stored during deformation
What is a hysteresis loop?
Area within the loop is the amount of energy absorbed during one load/unload cycle
By what percentage does Achilles tendon lose energy and how can it be improved?
10% - can be improved through resistance/strength training
What does high passive stiffness in tendons infer?
Reduced braking phase muscle activation - get tired later on in races
Reduced tendon strain
Reduced muscle activity = improved running efficiency