Flashcards in Mechanical Factors Deck (20):
What factors has strength shown to increase?
Rate of Force Development, Power, Jump Height
What are the different mechanical, architectural and neural factors?
Mechanical --> muscular action, moment arm
Architect --> CSA, pennation angle, fibre type
Neural --> MU's activated, stimulation frequency
What changes does power and strength training bring to performances?
Power --> increase neural drive, force and RFD
Strength --> increase neural drive, RFD and muscle thickness
What are the 3 ways in examining mechanical factors on force generation?
Single Fibre (in Vitro - stimulate a single fibre)
Whole Muscle (dependent on fibre type & design)
Joint Level (attached - in Vivo)
What is the difference in single fibre and whole muscle in terms of the force-length relationship?
SF = force greatest at intermediate lengths due to increase cross bridge attachments.
WM = combination of contractile and elastic properties -challenged by MTU and fibre length
What is the sticking region?
Point in the movement that is the hardest
What is shorter ROM linked to?
Improvements in jump height and strength performances
Increase training = angle-specific changes linked to neural control come about
What are some of the mechanical adaptations in terms of the length-tension relationship?
- Rectus Femoris adapts to cope with demands
- Cyclists perform better at shorter RF lengths whereas runners perform better at longer RF lengths
What is the difference between single fibre, whole muscle and joint level in terms of the force-velocity relationship?
SF = force exerted lowers as speed of shortening quickens due to limited binding sites
WM = max shortening velocity dependent on fibre type, length, pennation angle - power at max shorten is 1/3 of max velocity
JL = peak torque during concentric lowers as angular velocity quickens - slower this is = increased force
How can types of action affect velocity specificity?
1) Eccentric can produce more force than concentric through different mechanisms
2) Eccentric is more efficient
3) Eccentric presents neural control strategies
What are some of the mechanisms proposed from the SSC?
1) Reduced metabolic cost
2) Increased time for force generation
3) Increased storage and use of elastic energy
What affect does increasing stiffness/compliance have on our bodies?
Stiffness - Reduces contact time
Compliance - enhances performance and force output
Those who have higher stiffness perform better in SSC activities
What is torque variation due to?
Attachment location (moment arm. axons)
Contraction of multiple muscles to the net effect of a joint
What is moment arm?
Shortest distance from joint centre to the tendon
Affects the magnitude of torque produced by the muscle
What is the calculation for Torque?
T = Fd
What is the differences between force/effort arm and resistance arm?
What is needed to overcome resistance torque?
Force -> distance from axis to point of force application
Resi -> distance from axis to point of resistance application
Increased effort torque to overcome resistance torque
Why are there fluctuations in moment arm? and in what sort of athletes is this common?
Moment arm varies over range of movement.
Sprinters have increases in 'd' which improves Quad function
What do alterations in 'd' produce?
Increasing 'd' = increases force
Reducing 'd' = reduces force but good for faster activities
What are the physiological consequences of moment arm?
Triceps - moment arm is very short distance
Perpendicular from the elbow joint to where the tricep force comes from