Muscle and Tendon Flashcards
How do muscles differ?
- Size
- Fibre length
- Pennation angle
- Fibre type
- Tendon length
Give examples of different ratios of muscle fibres and how it affects joints
Long fibres and short tendons = large active range of motion at joints
Shorter fibres and long tendons = important for elastic
explain how kangaroos increase speed without metabolic cost
springy limbs reduce metabolic cost of locomotion
Explain the mechanism of springy limbs?
- KE and PE decrease in early stance
- KE and PE lower at mid stance
- -> Spring compressed
- spring recoil in late stance to return elastic energy to KE and PE of CoM
- reduces the amount of work muscles need to do to accelerate the body during each stride
what does elastic energy stored =
1/2 force x linear deformation
- for a given force, the more it deforms, the more energy it will store
Tendon strain must be high
What is the definition of stiffness?
- Its resistance to to deformation due to a force
What is the formula for stiffness?
Force / Change in length
What is the formula for compliance?
1 / stiffness
Young’s modulus (Pa)
Stress / Strain
What are the effects of a stiff tendon?
- the more force it can withstand/transmit
- the less it will strain for a given force
- the less energy it will store for a given force
What amount of tendon energy is lost to heat?
approximately 7%
What are the most elastic sites in the human body?
ankle joint and foot
Briefly describe the achilles tendon
- Free tendon of gastrocnemius and soleus
- strain during running
- high injury incidence
What are the invasive methods of measuring strain in tendons in vivo?
tendon buckle
fibre optics
What are the non invasive methods of measuring strain in tendons in vivo?
ultrasound
when will the opposed tendon heal
if it is partially ruptured
Describe the key features of ultrasound
High frequency sound wave
- sound is differentially reflected or absorbed by tissues of different densities
- cheap and available
- high skill level required
- soft tissues and bone surface
- difficult to get generl picture of the area
- low risk
Define tendinopathy
- tendon loaded to high strain, which is near failure limit of collagen fascicles
- this loading cycle is repeated 1000s of times
common sites for achilles tendinopathy
achilles
patella
tendon of origin extensor carpi radialis brevis
what are the risk factors for tendinopathy
- change in training
- high stress placed on tissue due to sub optimal technique
- inappropriate equipment
- inappropriate tendon stiffness
How do you adapt a tendon?
- by overload
–> repetitive loading above normal rate initiates normal collagen and extra cellular matrix synthesis and degradation
- -> diagram = degradation + synthesis
- if the rest between loading sessions is not adequate it results in tissues degradation
How can resistance training increase tendon stiffness?
- Due to an upregulation of collagen type 1 fascicles
- a stiffer tendon can resist more
