Muscle architecture Flashcards
Types of muscles (7)
Strap (parallel) Fusiform unipennate Bipennate Multipennate Circular Triangular (convergent)
What is ACSA and PCSA
Anatomical cross sectional area: 90 degrees to the muscles longitudinal axis. Shows you where the anatomical cross sectional area is calculated from.
Physiological cross sectional area: 90 degrees to muscle fibers longitudinal axis. Shows you where the Physiological cross sectional area is calculated from
Physiological cross sectional area is related to…
How strong the muscle is isometrically and ACSA isn’t necessarily the same sometimes but not always.
What does PCSA tell us?
The maximum isometric force that can be produced by a muscle. Number of parallel sarcomeres indicates strength.
Pennate muscle performance compared to strap like muscles.
Pennate muscles have a greater proportion of fibers in parallel and a lesser proportion in series. Compared to a strap-like muscle of the same volume, a pennate muscle will be stronger, have the lesser Vmax & reduced contractility.
F tendon = F fiber × cos σ
What did the experimenters discover when testing vastus lateralis medial gastrocnemius and medial gastrocnemius in 100m sprints?
Longer fascicle length of VL, GM & GL displays negative correlation with 100m sprint times in elite and sub-elite sprinters. The longer the fascicles the lower the sprint time.
What is a muscle strain/injury what is it caused by and what is an example?
Damage to the muscle fibers, it also involves tendon disruption. Normally caused by a high forced, eccentric contraction at long length mainly at the muscle tendon junction MTJ. An example would be hamstrings while sprinting.
Classifications of injuries
Minor- soreness, 1 week till fit
Grade 2- few weeks
Grade 3- very sever completely rupture of muscle with most likely surgery needed for repair.
What are the 3 major factors associated with hamstring strain?
Fascicle length: Less than 10.56 cm high chance of injury equal to or above less likely.
History: Having a previous hamstring injury increases your chance of re injuring it. if not decreased risk.
Age: People under 28.8 years of age are less likely to be injured however of age or older increased risk.
How can i change my fascicle length?
Going to the gym to cause Hypertrophy (more). If I don’t go to the gym muscles wont be used causing atrophy (less).
Pennation angles untrained vs trained
Pennation angles will increase with hypertrophy for example, vastus lateralis have around 8 degrees of pennation in an ultrasound where as elite power lifter will have around 23-33 degrees.
