1. Force-Length Relationship & Force-Velocity Relationship
Muscular Strength
Force-Length Relationship
&
Force-Velocity Relationship

2. How Could You Increase Force?
↑ # of Cross-Bridge (i.e. Actin-Myosin)
↑ Force Production

3. Force-Length Relationship
Too Short !
Too Long !

4. How do we measure Muscular Force?
Isolated Muscle
*Linear Force (in N or lbs)
Human Body
*Angular Force
(Torque; N*m or ft*lbs)

5. Terminologies Isometric Contraction Isotonic Contraction
“same length”
Isotonic Contraction
“same tension”
Isokinetic Contraction
“same speed”

6. Force-Velocity Relationship

7. Fatigue and Fiber Type
As a muscle contracts maximally many times the ability to generate force will decrease
The degree to which force decreases can be measured by percent torque decline or fatigue index
A rough estimation of fiber type can be made based on the decline in force production

8. Lab Procedure Torque vs Angle (3 subjects)
Isometric Contraction
@ 90˚ , 130 ˚, 170 ˚
Torque vs Velocity (3 subjects)
Isokinetic Contraction
@ 60 ˚/sec, 180 ˚/sec, & 300 ˚/sec
50 Repetition Fatigue (1 subject)
50 reps isokinetic contractions (180˚/sec)