Transcript Slide Show
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 Neurological factors Cross-sectional area Fiber type Muscle fiber activation Rate of motor unit activation Biomechanical factors Muscle architecture Force-length relationship Force-velocity relationship Humans: 2.6-2.8 mm 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. 2. 3. 4. 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 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 = 90° MIA = 90 ° JA = 150° JA = 120° MIA = 30 ° MIA = 60 ° JA = 45° MIA = 120 ° JA = 30° MIA = 150 ° Understanding Moment Arm Changes Through ROM JA = 90° MIA = 90 ° JA = 150° JA = 120° MIA = 30 ° MIA = 60 ° JA = 45° MIA = 120 ° JA = 30° MIA = 150 ° Understanding Moment Arm Changes Through ROM JA = 90° MIA = 90 ° JA = 150° JA = 120° MIA = 30 ° MIA = 60 ° JA = 45° MIA = 120 ° JA = 30° MIA = 150 ° Torque (Nm) Biceps Brachii Strength 0 90 Joint Angle (°) 180 Torque (Nm) Brachioradialis Strength 0 90 Joint Angle (°) 180 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 Shoulder Flexors Torque Flexion 0 0 indicates anatomical position 30 60 90 120 Joint Angle (degrees) 150 Varies according to force-length & MIA (moment arm) changes for all muscles in FMG Shoulder Flexors Resistance Muscle Torque Flexion 0 0 indicates anatomical position 30 60 90 120 Joint Angle (degrees) 150 Shoulder Flexors Resistance Muscle Torque Flexion 0 0 indicates anatomical position 30 60 90 120 Joint Angle (degrees) 150 Shoulder Flexors Resistance Muscle Torque Flexion 0 0 indicates anatomical position 30 60 90 120 Joint Angle (degrees) 150 Shoulder Flexors Resistance Muscle Torque Flexion 0 0 indicates anatomical position 30 60 90 120 Joint Angle (degrees) 150 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.