1 ' Biomechanics Flashcards
Forces are classified as either
Internal or external
Internal
Act within the object or system
External
Act on an object through some interaction
Forces contribute to the acceleration of resistance in a single plane
True
Stabilizer
A muscle whose torque prevents moment at a joint
Prime mover
The muscle that causes an action
Asymmetrical load
A single-sided or unbalanced load or weight distribution
Balance
A stable state characterized by the cancellation of all forces by equal opposing forces
Static equilibrium
Sum of all external forces acting on the body equal zero; determine the ability to balance
Energy
Capacity to do work
Work
Transfer of energy by a force acting to displace the body; equal to the product of the force and the distance through which it produces movement
Work can be either prosit ice or negative as long as there is movement
True
If weight is pressed overhead, the action is positive work; when the weight is lowered back down, the action is considered negative work
True
Mechanical energy has two forms:
Kinetic energy and Potential energy
Kinetic energy
Energy possessed by the body due to its motion
Potential energy
Suggests no movement; implies energy due to position, such as with a stretched rubber band muscle
The stretch-shortening cycle (SSC) uses kinetic energy transferred into potential energy and back into kinetic energy for increased force output
True
Power
Time rate of doing work (work divided by time)
Power output depends on the muscle’s contractile velocity; as it increases, maximal force decreases
True
Maximal power can be produced at about 50% of velocity capability
True
Total power output depends on the quantity of power and the time it is sustained
True
Torque
The turning effect created by a force about an axis
Muscular force moves limbs around their respective axis of rotation as defined by the joint
True
The further the resistance is held from the body, the longer the resistance arm, and the greater the magnitude of torque required to move the load
True
Resistance arm
Distance between the fulcrum and the resistance point
The more torque experienced during exercise, the greater the difficulty of the movement, even when the weight remains constant
True
Center of gravity (COG)
Point where the mass of an object is equally balanced
Changes in the COG may cause the body to work harder to establish static equilibrium, dynamic balance and/or stability
True
Kinetic chain
A group of body segments that are connected by joints and operate together to provide a wide range of motion for a limb
External force energy must be transferred across the kinetic chain to effectively join with internal forces
True
Energy leaked due to unstable segments will limit internal force application, reducing external force
True
Stability is achieved with
Mass of the object, height of the GOC, line of gravitational pull and base of support
The wider the base of support, the more stable an object will become (e.g., brick lying flat vs. on its side)
True
Enhanced stability is achieved when the width of the base of support is widest and in-line with the direction of the resistance
True
Angular momentum is commonly employed during exercise when excessive resistance is used
True
Most often generated from hip extension of Flexion to increase total force output
True
Prime movers preform less work and experience reduced training stress compared to the employment proper lifting technique
True
The body’s production of angular momentum from rotational inertia requires a force proportionate to the angular momentum to stop the movement
True
Prime antagonists that cannot manage the declaration requirements employ assistive musculature throughout the kinetic chain to help slow the movement
True
Antagonist
Told of a muscle whose torque opposes a preformed action
Agonist
Role of a muscle whose torque aids a preformed action; referred to as the prime mover
When the agonist muscle group surpasses the antagonist muscle group’s strength balance requirements, injuries will occur
True
Strength balance
The force production relationship between an agonist and antagonist muscle or group of muscles acting on a joint
