1. Properties of Biological Materials -- Skeletal Muscle
柴惠敏
台灣大學 物理治療學系

2. 主要參考書
Nordin, M. & Frankel V.H., Basic Biomechanics of the Musculoskeletal System, 3rd ed. Philadelphia, PA, Lea & Febiger. Chapter 6.

3. Properties of Biological Materials -- Skeletal Muscle
Basic Concepts

4. Classification of Muscles
Striated muscles
skeletal muscles: voluntary contraction
cardiac muscles
non-striated (smooth) muscles

5. Function of Skeletal Muscle
To create motion by producing force
To provide strength
To protect joints by absorbing shock

6. Components of Skeletal Muscles
Fascia
Epimysium
Fascicle
perimysium
muscle fiber (cell)
endomysium
sacrolemma
myofibril: myosin and actin

7. Components of Muscle Fibers
muscle fiber: a long cylindrical cell with hundreds of nuclei
m in diameter
1-30 cm in length
myofibril: contractile component
Biomechnics is a discipline of science, newly developed and in the process of becoming established.
myosin
crossbridge
actin

8. Sliding Filament Mechanism
AF Huxley & HE Huxley, 1964
active shortening of sacromere, resulting from the relative movement of actin and myosin filaments with retaining its original length
force of contraction is developed by the crossbridges of myosin

9. Movement of Cross Bridges

10. Excitation-Contraction Coupling
An action potential in the sacrolemma provides electrical signal which triggers calcium ions undergoing chemical reactions of contraction

11. Types of Muscle Contraction
Static work
isometric contraction
Dynamic work
concentric contraction
eccentric contraction
isokinetic contraction

12. Isokinetic Contraction
joint moment
Isokinetic mg M 
Isotonic
joint angle F

13. Force Production in Muscle
Length-Tension relationship
Load-Velocity relationship
Force-Time relationship

14. Length-Tension Relationship
The tension that a muscle generates varies with its length
Obtained under isometric contractions and for maximum activation of the muscle

15. Length-Tension Curve of A Single Muscle Fiber
sacromere length
tension
resting length

16. Length-Tension Curve total tension tension active passive tension

17. Mechanical Model of Skeletal Muscle Fiber
parallel elastic component
series
elastic
component
contractile component

18. Length-Tension Curve
length
tension
total tension
active
passive

19. Force-Velocity Curve Hill’s model
contraction velocity
force
eccentric concentric
isometric

20. Force-Time Curve
isometric force
force
time

21. Effect of Temperature
temperature  nerve conduction velocity  frequency of stimulation  muscle force 
temperature  enzyme activity  efficiency of muscle contraction 
temperature  elasticity of collagen  extensibility of muscle  muscle force 

22. Muscle Atrophy  cross-sectional area of fibers
 number of muscle fibers
 aerobic capacity by changing the proportion of muscle fiber types
sedentary people:  # of type I fibers
athletes:  fiber type affected by that sports

23. Muscle Hypertrophy By physical training By electric stimulation
 cross-sectional area of muscle fibers
 number of muscle fibers
change in proportion of muscle fiber types
By electric stimulation

24. Single Fiber Twitch ms S
contraction