put it all together compare muscles w/two different pcsas – draw f-l for same fiber length –...
TRANSCRIPT
Put it all together• Compare muscles w/two different pcsas– Draw F-L for same fiber length– Draw F-V for same fiber length
• Compare muscle w/different fiber lengths– Draw F-L, for same pcsa– Draw F-V, for same pcsa
Muscle Length (mm)
Max
For
ce (N
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Max
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Muscle Velocity (mm/s)
Muscle Length (mm)
Max
For
ce (N
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Muscle Velocity (mm/s)
Max
For
ce (N
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Muscle Length (mm)
Max
For
ce (N
)
Muscle Velocity (mm/s)
Max
For
ce (N
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Same fiber lengthDifferent PCSA
Different fiber lengthSame PCSA
Design problem
• Rectus femoris– Mass: 84 g– Fiber length: 6.6cm– Average CSA: 12.7 cm2
– Pennation Angle:5o
• Semitendinosous– Mass: 76.9 g– Fiber length: 15.8cm– Average CSA: 5.4 cm2
– Pennation Angle:5o
Design problem
• Rectus femoris– Mass: 84 g– Fiber length: 6.6cm– Average CSA: 12.7 cm2
– Pennation Angle:5o
• Biceps femoris– Mass: 128 g– Fiber length: 8.5cm– Average CSA: 12.7 cm2
– Pennation Angle:0o
• Vastus Lateralis– Mass: 220 g– Fiber length: 6.5cm– Average CSA: 30.6 cm2
– Pennation Angle:5o
Design problem
• Rectus femoris– Mass: 84 g– Fiber length: 6.6cm– Average CSA: 12.7 cm2
– Pennation Angle:5o
• Biceps femoris– Mass: 128 g– Fiber length: 8.5cm– Average CSA: 12.7 cm2
– Pennation Angle:0o
• Vastus Lateralis– Mass: 220 g– Fiber length: 6.5cm– Average CSA: 30.6 cm2
– Pennation Angle:5o
ABC
Fiber Length/Muscle Length ratio
Examples of Muscle Structure/Function
• Quads– High pennation angles– Large PCSAs– Short fibers– Large forces
• Hamstrings– Long fibers, intermediate PCSAs– Large excursions
• Plantarflexors• Dorsiflexors• Dangerous generalization:– Anti-gravity extensors for force production– Flexors for high-velocity excursion– Will break down under close scrutiny