1. Muscle

2. Most abundant tissue (40-45% of BW)

3. Muscle Composition endomysium – loose CT surrounding each fiber perimysium – dense CT that bundles multiple fibers into fascicles epimysium – fibrous CT that surrounds entire muscle (fascia)

4. Muscle

5. Collagen in perimysium / epimysium  tendons Contraction  forces transported thru CT  tendons (inert)  bones.

6. Musculotendinous Unit Tendon - spring-like elastic (very stiff- tight) In series with muscle (SEC)

7. Musculotendinous Unit Epimysium, perimysium, endomysium, and sarcolemma  PEC parallel w/ contractile component

8. Musculotendinous Unit CC PEC SEC

9. Functions of Elastic Components Ensure readiness for contraction Ensure contractile elements return to resting position May prevent overstretching of passive elements

10. Functions of Elastic Components SEC and PEC are viscoelastic: absorb energy  to rate of force application dissipate energy in time dependent manner

11. Storage of Elastic Energy SEC can store elastic energy Return it to system Plyometrics

12. Quick stretch/prestretch loads SEC  counter-movement Elastic energy is returned to system and movement is carried out

13. Types of Contraction Eccentric > Isometric > Concentric Eccentric/Isometric supplemental tension thru SEC longer contraction times  greater cross-bridge formation

14. Types of Contraction Isokinetic – constant velocity  accommodating resistance Isotonic – constant tension on muscle throughout ROM

15. Types of Contraction Isoinertial constant resistance int. torque  resistance  isometric int. torque > resistance  concentric

16. Types of Contraction Isoinertial simulate ADL inertia is overcome muscle contracts concentrically and torque is submaximal

17. Force Production Length–tension relationship Tension/force is greatest when @ resting position

18. Length-Tension Relationship

19. Length Tension Resting Length Total Tension Passive Tension Active Tension

20. Length-Tension Relationship CC --> Active Tension SEC and PEC --> Passive Tension > length --> greater contribution of elastic component to total tension

21. Length-Tension Relationship Single joint vs. 2 joint muscles

22. Length-Tension Relationship Constant muscular tension Lower metabolic cost for eccentric contractions Mechanical energy is stored in elastic components

23. Length-Tension Relationship Length Tension Short-fiber muscle of large cross-section Long-fiber muscle of small cross-section

24. Force-Velocity Curve Velocity Load Isometric 0 EccentricConcentric Force

25. Architecture Pennation Fiber Length PCSA

26. Pennation F T = F M cos 

27. Fiber Length 40 - 100 mm sartorius (450 mm) semitendinosus (160 mm) soleus (20 mm)

28. Fiber Length longer fibers  # of sarcomeres  range of excursion producer  velocity shorter fibers greater ability to produce force

29. PCSA Linearly related to max force output Relationship between PCSA and Fiber Length

30. PCSA and Fiber Length

31. Effect of Temperature  in conduction velocity  in frequency of stimulation   in force production

32. Effect of Temperature  in metabolism   efficiency of muscle contraction  in elasticity of collagen in SEC and PEC   extensibility in musculotendinous unit

33. Mechanisms of  temperature  in blood flow thru warming up/exercise  in metabolism, release of energy from contractions, friction (contractile components

34. Muscle Injury & Mobilization Early motion may reduce atrophy Generation of // fiber orientation More rapid vascularization Tensile strength returned more quickly

35. Muscle Disuse Selective atrophy of Type I fibers electrical stimulation may help minimize atrophy

36. Resistance Training Hypertrophy vs. hyperplasia Alteration of fiber type

37. Resistance Training Basic Concepts: Apply resistance Progressive overload PRE

38. Stretching muscle flexibility maintains/increases joint ROM  elasticity and length of musculotendinous unit permits musculotendinous unit to store energy (time and amplitude dependent) in SEC and contractile components

39. GTO in series with contractile proteins (extrafusal) – respond to increase in tension  inhibit contract and enhance relaxation

40. Intrafusal muscle spindles Primary respond to changes in rate of lengthening dynamic response strong

41. Intrafusal muscle spindles Secondary respond to the actual length change static response weak

42. Conflicts rate of stretch slow may bypass the dynamic response negating the spindles

43. Main Goal inhibit muscle spindle effect and promote Golgi effect  enhance stretch