1. Kinesiology Andrew L. McDonough, PT, EdD Dominican College
Physical Therapy Program

2. “Kinesiology” Functional anatomy (traditional) Biomechanics Statics
Dynamics
Kinematics (geometry of motion)
Kinetics (forces that account for motion)

3. Voluntary Movement Factors & Levels of Analysis
(Macro)physiologic
Biomechanics
Motor control
Motor learning

4. Types of Motion Translatory Rotary – constant radius
A B
Rotary – constant radius
Curvilinear – radius varies

5. Basic Components of a Joint System
Muscle attachments (proximal – distal)
Axis of rotation
Fixed center
Instant center
Innervation

6. Terms Agonist – Antagonist (context-dependent)
Synergist (3 definitions)
Primary vs. Secondary (Tertiary) movers
Fixators/stabilizers – Immobilizers

7. Muscle Factors
Physiological cross-section
Geometry of muscle/tendon

8. Physiological Cross-Section
Less force
More force

9. Geometry Type types Fusiform (cigar-shaped) Penniform (feather-shaped)
Bi-pennate
Uni-pennate
Multi-pennate
Bi-
Uni-
Multi-

10. Significance of Geometry
Fusiform
Parallel arrangement of fibers (all have same proximal and distal attachments)
Virtually ALL (less ~10%) of force delivered to attachments
Have large force (torque) generating potential
Muscles/fibers to be impulsive but not endurant

11. Significance of Geometry
Penniform
Implies an angle-of-insertion
Gross muscle level
Muscle fiber level .
angle-of-insertion

12. . . Angle-of-insertion T = f x d resultant force X axis rotary
component (“Y”)
force .
900
(joint) compressive
component (“X”)
T = f x d

13. Muscle Contraction Types
Isometric
Isotonic
Concentric (shortening contraction)
Eccentric (lengthening “contraction”)
Isokinetic (?)

14. Muscle Contraction Levels of Analysis
Sarcomere (microanatomical)
Gross muscle

15. Isometric Contraction
Sarcomere shortens delivering force to tendon
Gross length remains constant
Demo

16. Concentric Contraction
Sarcomere shortens
Gross muscle shortens pulling on bony attachments
If the muscle crosses a joint – the joints moves through a ROM via torque created
Demo

17. Eccentric “Contraction”
A “lengthening reaction”
Occurs in a muscle that has already undergone a concentric contraction
External force applied exceeds internal muscular force being generated
Muscle lengthens under neuro-motor control

18. Sources of Tension Muscle (“contractile element”)
Tendon (“non-contractile element” = CT)

19. Premise: Concentric vs. Eccentric Contractions
“Per comparable volumes of muscle tissue, more tension will always be realized during eccentric contractions.”

20. Analysis Concentric contraction Eccentric contraction
Source of tension
Contractile elements (muscle)
Eccentric contraction
Non-contractile elements (CT = tendon)
The tendon is in a pre-loaded condition due to previous concentric contraction

21. EMG Activity Ratio: 0.5 : 1.0 (eccentric : concentric)
Tension realized is the sum-total of contractile & non-contractile elements
Muscle working eccentrically will not have to “work as hard” since some the total tension is provided by the pre-loaded tendon

22. Metabolic Activity
Consequently if the muscle is not working as hard under eccentric control less energy is required to sustain a contraction by a factor of 10 – 30%
Less lactic acid is produced eccentrically

23. Muscle Contraction & Fiber Types
Concentric: Type I and IIa motor units most active
Eccentric: Type IIb motor units most active

24. Relationship Between a Muscle (or Muscle Fiber) & Tension Production
Blix experiments
probe
dynamometer
frog soleus muscle fiber

25. Muscle Lengthened Passively
Tension production will soon become linear and muscle fiber will react elastically
Passive Tension Curve
Tension
Length

26. Muscle Stimulated at Various Pre-set Lengths
Shortening Lengthening 60
Blix Curve or
“Length-tension Curve”
Tension
100%
Rest length
Length

27. Length-Tension Relationship
“During active contraction a muscle (or muscle fiber) will generate maximal tension at or slightly greater than rest length.”
Levels of analysis
Gross muscle
Muscle fiber/sarcomere
Demo

28. Motor Control System
Constantly evaluates tension via length assessment (GTOs & spindles)
Often optimizes tension via maintaining muscle length
Usually “goes out of its way” to maintain length

29. Question
What happens when a muscle is called upon to do the job it is intended to do (i.e., shorten)?

30. Muscle Types
One-joint
Two (two-or-more)-joint

31. Active Insufficiency
Two-joint muscle shortens simultaneously over both joints
Rapidly loses length (shifts left on the length-tension curve)
Force and torque production decrease quickly

32. Two-Joint Muscles General Rule
In a motor control context, two-muscles rarely contract over both (all) joints simultaneously
While one end of the muscle is shortening over its associated joint
The other end is being lengthened over its associated joint
The net effect: preserve length and therefore force and torque
Motor control system avoids active insufficiency in most cases

33. Passive Insufficiency
Muscle passively elongated over both (all) joint simultaneously
At some point the muscle reaches its elastic limit
ROM will be limited across both joints

34. Velocity – Tension Relationship
Eccentric
Concentric
“Inverse Relationship”
Tension - +
100
Demo
Velocity

35. Other Terms Strength – ability to generate tension
Power – rate of doing work (T=f x d)
Low power
High power
Endurance – ability to sustain the work being preformed

36. Other Terms
Arthrokinematics – study of the relationship between (among) articulating bony surfaces
Joint play
Congruency
Component motion
Overall motion