Tendon Flashcards
Tendons have a hierarchical structure, but how do they differ from ligaments?
Tendons have more parallel fibres to translate force from muscle to bone better. Ligaments are not so uniform, to allow for twisting
What are the properties of tendons mentioned in the slides?
Tendons have a dry mass of 30% of their total mass (70%) water.
Predominantly collagen and less than 3% elastin
Describe the Load-deformation graph presented in the slides?
When we first put a load on a tendon, it will stretch before we see any large increases in load. This is known as the toe region of the curve and represents the crimped structure of the tendon straightening. With increasing load, the deformation curve increases linearly until it cannot be stretched anymore. Further load will cause damage to the tendon. Known as the yield and failure region.
What are the two types of tendon?
Energy storing and positional tendons.
Energy storing: can stretch 12-15% before tearing
Positional: can stretch 6-8% before ripping.
Why is damaging a tendon a bad bad thing?
Tendons take much longer to heal than other tissues because:
- low levels of blood supply
- Turn over of tissues is very slow
- collagen remodelling takes longer than bone
What did Faseb (2013) show regarding healing times and tendons?
Tendon turnover is so slow that patients who were alive before nuclear bomb testing (1955-1663)in still reported nuclear c14 in there tendon tissues in 2013
What is the Aponeurosis?
Is a large flat part of the tendon where the muscle and tendon interlink. It has a very complex structure. This connection is very strong, however near the aponeurosis, where the muscle fibres change their orientation to fit to tendon is an area of weakness.
Why are tendons referred to as Visco-elastic?
Tendons have different reactions at different speeds, and are not 100% efficient when transferring energy
Why do sprinters want stiff tendons?
Sprints need to produce for in short periods of time, increases in tendon stiffness correlate linearly with rate of force development due to stiff tendons maximising energy transfer.
Why do tendons make muscle usage more efficient? and can potentially mitigate problems associated with the force-length relationship?
firstly tendons do not use energy during contraction. Secondly, when a force is applied to a tendon, it stretches until it is stiff, at this point the muscle has not been overly stretched, therefore has not been stretched out of a good force-length position to apply bigger forces.
What is the contractile component and the series elastic component?
What are the equations of muscle length and muscle velocity?
CC- everything within the muscle
SEC- the tendon
Muscle length= CC length + SEC length
Muscle velocity= CC velocity + SEC velocity
What are the effects of the SEC on muscle fibre length?
Tendons store and return energy at different times, making movements such as walking more efficient. Without tendons, huge muscle ROM and shortening would have to occur, but tendons utilise their elastic components to accommodate the movement meaning less muscle force is required. This also means muscle fibres are kept within their optimal fibre length, and any force they produce will require less energy because they don’t have to be as active.
What are the effects of the SEC on muscle fibre velocity?
Tendons allow body parts that require high levels of dexterity to be light and not packed with muscle to control movement. The shank and foot of a horse, for example, is both slender and has a small inertia. The large muscles packed around the thighs of the horse can apply large forces through the tendons within the shank and foot to run very quickly.
What were the key discussion points regarding elastic contributions to power?
The graph showed much greater power output with elastical components than without.
However, it was said that not all difference can be explained by elastic components.
Without elastic components, the muscle fibres are required to shorten more at higher velocities reducing their power output.
Think force-length and force-velocity-power graphs
During a plyometric, optimising the stretch-shortening cycle load is important for efficiency. What type of loading is best for effeciency?
Landing with a medium muscle force is the most efficient loading strategy. High landing forces receive a large muscle force in return, but because the muscle is highly activated, the energy coast is large due to the concentric and eccentric components of the jump.
During a medium landing force, the muscle does not change length, where instead the tendon does. This means no energy is lost due to muscle length changes.
