Architectural and Structural Factors Flashcards
What are structural parts of the muscle?
Epimysium, Perimysium, Endomysium, Myofibrils
Thick & Thin Filaments, Cross-bridges
Troponin and Tropomyosin
What is the architecture of the muscle?
CSA, Pennation Angle, Fibre Length
What is CSA?
What is PCSA and ACSA and the differences?
How big the muscle is - max force is proportional to the number of fibres placed parallel to another
PCSA = physiological = fibre direction ACSA = anatomical = perpendicular to long axis
What are some methods for measuring CSA?
Ultrasound, MRI, CT Scan, DEXA
What are some of the flaws in studies measuring for CSA?
Poor muscle size measurements
Small sample size
Day-to-day variability
How does body size affect strength?
Larger people generally stronger than smaller people
However normalisation according to body weight would prove otherwise
Larger people have larger moment arms
What are the key properties of Motor Unit types?
How can you measure these?
Contractile Speed (time to peak force) MU force (amplitude of twitch) Fatigueability (reduced peak force)
Via direct/indirect methods - examine MU twitches
What is the difference between Type I and Type II Motor Units?
Type I = slow contractile, fatigue resistant
Type II = fast contractile, large neuron size and diameter
What are the 2 different fibre organisation and pennation types and what do they mean?
In-series = increases ROM and faster contractions
Parallel = increases ROM and more force production
What is the difference between pennate and non-pennate muscles?
Pennate = fibres arranged around one/many central tendons
Non-pennate = parallel to the muscles line of pull (fusiform)
How does pennated muscles affect influence, thickness and training abilities?
Increases strength = Increases force production
Increases thickness of the muscle
Increases amount of fibres in set volume and reduces force transmission to the central tendon
What is the relationship between fibre length and CSA?
What happens if you have a longer fibre?
Increase CSA = Reduced fibre length
Longer fibre = Increased ROM and contraction velocity
What happens if you have an increased fascicle length?
Limits the degree of change in pennation angle
How does fibre length relate to injury?
Eccentric contractions increase fascicle length
Nordic hamstrings reduce this length and increases pennation on previous injured legs
What is the relationship between the soleus and gastrocnemius in terms of fibre lengths?
What is the relationship between the hamstrings and quadriceps in terms of fibres?
Soleus => Increased CSA, Reduced FTF, Large pennation
Gastroc => balanced fibres, faster but fatigue more
Hamstrings => Fusiform (increase contraction reduce force)
Quads => Pennate (dominant muscle and increase force)
