Chapter Two: Biomechanics of Resistance Exercise Flashcards
Biomechanics
- Mechanisms by which the musculoskeletal components interact to produce movement
Muscle Origin
- Proximal attachment (closer to midline)
Muscle Insertion
- Distal attachment (farther from midline)
Agonist
- Primary muscle involved in a movement
- Example: Triceps with elbow extension
Antagonist
- Muscle that can slow down or stop movement
- Example: Biceps during rapid elbow extension
Synergist
- Muscle that facilitates or participates in a movement
- Example: Scapular stabilizers during overhead movements
Levers of the Musculoskeletal System: First class lever
- A lever for which the muscle force and resistive force act on opposite sides of the fulcrum
Levers of the Musculoskeletal System: Fulcrum
- The pivot point of a lever
Levers of the Musculoskeletal System: Lever
- A body that, when subjected to a force on one side of a pivot point, exerts force on any object impeding its tendency to rotate
Levers of the Musculoskeletal System: Mechanical Advantage
- Applied muscle force has to be less than the resistive force to produce an equal amount of torque
- Represented as a ratio greater than 1.0
- (Ratio less than 1.0 indicates a mechanical disadvantage, more muscle force than the amount of resistive force present)
Levers of the Musculoskeletal System: Moment Arm
- The perpendicular distance from the line of action of force to the fulcrum.
Levers of the Musculoskeletal System: Muscle Force
- Force generated by biomechanical activity or the stretching of non-contractile tissue that tends to draw the opposite ends of a muscle toward each other
Levers of the Musculoskeletal System: Resistive Force
- Force generated by a source external of the body that acts contrary to muscle force
Levers of the Musculoskeletal System: Second Class Lever
- A lever for which the muscle force and resistive force act on the same side of the fulcrum
- Longer moment arm than that through which the resistive force acts
- More mechanical advantage due to long moment arm=less muscle force required to move resistance
- Example: Calf muscles raising the body on the balls of the feet
Levers of the Musculoskeletal System: Third Class Lever
- A lever for which the muscle force and resistive force act on the same side of the fulcrum
- Shorter moment arm than that through which the resistive force acts
- Less mechanical advantage due to short moment arm =more muscle force required to move resistance
Example:
Levers of the Musculoskeletal System: Torque
- The degree to which a force tends to rotate an object about a specified fulcrum
- (Force X length of moment arm)
Variations in Tendon Insertion
- There is a large degree of anatomical difference between individuals
- Differences in tendon insertion contribute to different advantages and disadvantages
- Tendon insertions farther from the fulcrum lead to increased moment arm for the muscle force which contribute to greater degrees of force production but less torque production
- This causes increased ability to move weight and decreased ability to generate force at high speed of movement
- Tendon insertion closer to the fulcrum lead to decreased moment arm for muscle force generation but increased torque generation
- This causes decreased ability to move weight but increased ability to generate force at high speed of movement
Anatomical Planes and Major Body Movements: Sagittal Plane
- Divide the body into left and right
Anatomical Planes and Major Body Movements: Frontal Plane
- Divides the body into front and back
Anatomical Planes and Major Body Movements: Transverse Plane
- Divides the body into top and bottom
Anatomical Planes and Major Body Movements: Application
- Exercises for a specific joint should be incorporated in all planes
- Working joints in all planes can adequately strengthen them for movements that combine multiple planes
Human Strength and Power: Strength
- The ability to exert force
Human Strength and Power: Acceleration
- Change in velocity per unit time
Force=Mass X Acceleration
Human Strength and Power: Strength Vs Power
- Strength = the ability to exert force at any given velocity
- Power = the product of force and velocity at whatever speed
- It is important to train athletes with parameters that fit their given activity
Human Strength and Power: Positive Work and Power: Power
- Time rate of doing work
Power=Work/Time
Human Strength and Power: Positive Work and Power: Work
- The product of the force exerted on an object and the distance the object moves in the direction in which the force is exerted
(Work=Force X Displacement)
Human Strength and Power: Negative Work and Power:
- When a resistive force moves downward the resulting calculations are negative
- There is no negative work or power
- Technically in this scenario the resistive force is performing work on the body as the resistive force moves downward with gravitational force
Human Strength and Power: Angular Work and Power: Angular Displacement
- The angle through which an object rotates
Human Strength and Power: Angular Work and Power:
Angular Velocity
- The objects rotational speed measured in radians per second
Human Strength and Power: Angular Work and Power: Torque
- Measured in Newton meters
- Distance component of the torque unit refers to the length of the moment arm which is perpendicular to the line of action of the force