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Exercise Evaluation. Exercise Evaluation. Strength curve similarity. Strength Curve (Kulig et al., 1984). strength curve – plot of how maximum strength varies as a function of joint angle - PowerPoint PPT Presentation
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Exercise Evaluation
Exercise Evaluation
Strength curve similarity
Strength Curve (Kulig et al., 1984)
strength curve – plot of how maximum strength varies as a function of joint angle
strength - the ability of a muscle group to develop torque against an unyielding resistance in a single contraction of unrestricted duration
Mobility Determined by Torque Output
Factors that Affect Muscle Torque Output Force Moment arm
Point of force application (attachment site) Angle of force application (muscle insertion
angle)
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
Humans: 2.6-2.8 m
Active Component
Passive component
Total Force
Single Joint Muscles
60% 110-120% 160%
Multi Joint Muscles
60% >160%
Mobility Determined by Torque Output
Factors that Affect Muscle Torque Output Force Moment arm
Point of force application (attachment site) Angle of force application (muscle insertion
angle)
Muscle Attachments
1. Further from joint is better (theoretically)
2. Structural constraints negate #1
3. Cannot alter attachment sites
4. Strength differences due, in part, to attachment differences
Muscle Insertion Angle
1. 90 is better
2. MIA typically < 45
3. MIA not constant through joint ROM, affecting strength through ROM
4. Cannot alter MIA
5. Strength differences due, in part, to MIA differences
Understanding Moment Arm Changes Through ROM
JA = 150° JA = 120°MIA = 60 °
JA = 90°MIA = 90 °
JA = 45°MIA = 120 °
JA = 30°MIA = 150 °MIA = 30 °
Understanding Moment Arm Changes Through ROM
JA = 150°MIA = 30 °
JA = 120°MIA = 60 °
JA = 90°MIA = 90 °
JA = 45°MIA = 120 °
JA = 30°MIA = 150 °
Understanding Moment Arm Changes Through ROM
JA = 150°MIA = 30 °
JA = 120°MIA = 60 °
JA = 90°MIA = 90 °
JA = 45°MIA = 120 °
JA = 30°MIA = 150 °
Biceps Brachii Strength
Joint Angle (°)
Tor
que
(Nm
)
0 90 180
Joint Angle
Brachioradialis Strength
Joint Angle (°)
Tor
que
(Nm
)
0 90 180
Joint Angle
Summary of System Level Rotational Function
Torque output varies across ROM Variation depends on:
Force-length changes Moment arm changes
Variation differs across muscles & joints
Torque
Joint Angle (degrees)
0 30 60 90 120 150
Shoulder Flexors
Flexion
0 indicates anatomical position
Varies according to force-length & MIA (moment arm) changes for all muscles in FMG
Torque
Joint Angle (degrees)
0 30 60 90 120 150
Shoulder Flexors
Flexion
0 indicates anatomical position
Resistance
Muscle
Torque
Joint Angle (degrees)
0 30 60 90 120 150
Shoulder Flexors
Flexion
0 indicates anatomical position
Resistance
Muscle
Torque
Joint Angle (degrees)
0 30 60 90 120 150
Shoulder Flexors
Flexion
0 indicates anatomical position
Resistance
Muscle
Torque
Joint Angle (degrees)
0 30 60 90 120 150
Shoulder Flexors
Flexion
0 indicates anatomical position
Resistance
Muscle
Exercise Evaluation
Strength curve similarity Specificity of muscle roles Specificity of ROM Specificity of movement & contraction speed
Summary
Exercise evaluation is important to ensure appropriate physical training, whether for performance enhancement, injury prevention, or injury rehabilitation.
Exercise evaluation should focus on the progressive overload principle and the specificity principle.
The importance of each principle depends on the goal(s) of the exercise program.
