1. Course Content I.Introduction to the Course II.Biomechanical Concepts Related to Human Movement III.Anatomical Concepts Related to Human Movement IV.Qualitative Analysis of Human Movement

2. Anatomical Concepts Related to Human Movement A.The Skeletal System B.The Muscular System C.The Nervous System

3. The Muscular System 1.Organ Level Structure & Function 2.System Level Structure & Function 3.Injury to the Musculoskeletal System

4. The Muscular System I.Organ Level Structure & Function II.System Level Structure & Function III.Injury to the Skeletal System IV.Musculoskeletal Function

5. General Structure ~ 434 muscles 40%-45% of body weight 75 pairs of muscles Organized into compartments Utilizes 50% of body’s metabolism Controlled by somatic nervous system

6. General Function Provides force/torque for movement Maintenance of upright posture Body transport Object manipulation Aids in venous return Maintains body temperature

7. Organ Level Structure and Function Structure of the Muscle Organ Function of the Muscle Organ

8. Organ Level Structure and Function Structure of the Muscle Organ Function of the Muscle Organ

9. Muscle Tissue – Active Component

11. Properties of Skeletal Muscle Tissue Excitability (Irritability) Conductivity Contractility Extensibility Elasticity

12. Connective Tissue – Passive Component

13. Nerve Tissue – Passive Component

14. Structure of the Muscle Organ Muscle organ: 40,000 -1,000,000 fibers Fascicle:10-200 fibers Fiber:8000 fibrils

15. Muscle Compartments

16. Organ Level Structure and Function Structure of the Muscle Organ Function of the Muscle Organ

17. Force Production

18. Series & Parallel Elastic Tissue

20. Factors That Affect Force Output Physiological factors Cross-sectional area Fiber type Neural factors Muscle fiber activation Rate of motor unit activation Biomechanical factors Muscle architecture Force-length relationship Force-velocity relationship

21. Physiological Factors: CSA Training?

22. Physiological Factors: Muscle Fiber Type Type I Red, SO, slow-twitch Type IIa Red, FOG, fast-twitch, intermediate Type IIb White, FG, fast-twitch Training??

23. Percentage of Type I Fibers in Human Skeletal Muscle Muscle% % Obicularis oculi15Quadriceps52 Biceps brachii38-42First DI57 Triceps brachii33-50Abductor pollicis brevis63 Extensor digitorum brevis 45 Masseter60-70 Vastus lateralis46Tibialis anterior73 Gastrocnemius (L)49Adductor pollicis80 Diaphragm50Soleus80

24. Factors That Affect Force Output Physiological factors Cross-sectional area Fiber type Neural factors Muscle fiber activation Rate of motor unit activation Biomechanical factors Muscle architecture Force-length relationship Force-velocity relationship

25. Neurological Factors: Muscle Fiber Activation  All-or-None Principle  Same fiber type within MU  10-2000 fibers per MU  120-580 MUs / muscle  MU size influences precision & force of movement

26. Neurological Factors: Muscle Fiber Activation  # of activated MUs,  force Training?

27. Neurological Factors: Rate of Motor Unit Activation  rate of MU activation,  force

28. Single Twitch Multiple Twitch Tetanus Training??

29. Factors That Affect Force Output Physiological factors Cross-sectional area Fiber type Neural factors Muscle fiber activation Rate of motor unit activation Biomechanical factors Muscle architecture Force-length relationship Force-velocity relationship

30. Nonpennate MusclePennate Muscle

31. Ranges of Muscle Pennation in Humans (Yamaguchi et al., 1990) Muscle Pennation Angle (deg) Gluteus maximus3.4-5.0 Gluteus medius8.0-19.0 Gluteus minimus5.0-21.0 Biceps femoris7.0-17.0 Gastrocnemius (medial)6.5-25.0 Gastrocnemius (lateral)8.0-16.0

32. Fiber Density - PCSA

33. Nonpennate MusclePennate Muscle

34. CSA & PCSA of Ankle Plantar Flexors (Fukunaga et al., 1992) Muscle CSA (cm 2 ) PCSA (cm 2 ) Medial gastrocnemius16.4968.34 Lateral gastrocnemius11.2427.78 Soleus29.97230.02 Flexor hallucis longus4.8519.32 Tibialis posterior5.4036.83 Flexor digitorum longus1.599.12

35. Biomechanical Factors: Muscle Architecture Pennate Greater force (force ~ PCSA) Non-pennate Greater range of muscle lengths Larger ROM Greater operating range Shorten at higher velocities Training?

36. Factors That Affect Force Output Physiological factors Cross-sectional area Fiber type Neurological factors Muscle fiber activation Rate of motor unit activation Biomechanical factors Muscle architecture Force-length relationship Force-velocity relationship

37. Humans: 2.6-2.8  m

38. Active Component

39. Passive component

40. Total Force

41. Single Joint Muscles 60% 110-120% 160%

42. Multi Joint Muscles 60% >160%

43. Factors That Affect Force Output Physiological factors Cross-sectional area Fiber type Neurological factors Muscle fiber activation Rate of motor unit activation Biomechanical factors Muscle architecture Force-length relationship Force-velocity relationship

44. 110-180% isometric Biomechanical Factors: Force-Velocity Relationship EccentricConcentric Velocity

45. Factors that Affect Force Output Physiological factors Cross-sectional area Fiber type Neurological factors Muscle fiber activation Rate of motor unit activation Biomechanical factors Muscle architecture Length-tension relationship Force-velocity relationship

46. Summary Numerous factors affect the force output of the muscle organ. Identification of these factors allows us to better understand muscle strength and explore alternative training methods that may be effective in increasing muscle strength.