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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
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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
60% 160% Single Joint Muscles 110-120%
Multi Joint Muscles >160% 60%
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 • Further from joint is better (theoretically) • Structural constraints negate #1 • Cannot alter attachment sites • Strength differences due, in part, to attachment differences
Muscle Insertion Angle • 90 is better • MIA typically < 45 • MIA not constant through joint ROM, affecting strength through ROM • Cannot alter MIA • Strength differences due, in part, to MIA differences
Understanding Moment Arm Changes Through ROM JA = 90° MIA = 90 ° JA = 45° MIA = 120 ° JA = 30° MIA = 150 ° JA = 150° JA = 120° MIA = 60 ° MIA = 30 °
Understanding Moment Arm Changes Through ROM JA = 90° MIA = 90 ° JA = 45° MIA = 120 ° JA = 30° MIA = 150 ° JA = 150° MIA = 30 ° JA = 120° MIA = 60 °
Understanding Moment Arm Changes Through ROM JA = 90° MIA = 90 ° JA = 45° MIA = 120 ° JA = 30° MIA = 150 ° JA = 150° MIA = 30 ° JA = 120° MIA = 60 °
Biceps Brachii Strength Torque (Nm) 0 90 180 Joint Angle (°) Joint Angle
Brachioradialis Strength Torque (Nm) 0 90 180 Joint Angle (°) 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
Varies according to force-length & MIA (moment arm) changes for all muscles in FMG 0 indicates anatomical position
Resistance Muscle 0 indicates anatomical position
Resistance Muscle 0 indicates anatomical position
Resistance Muscle 0 indicates anatomical position
Resistance Muscle 0 indicates anatomical position
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.