Question | Answer |
Contraction is | when tension is developed in a muscle as result of a stim
Used to:
Cause
Control
Prevent
Accelerate mvmnt
Deccelerate mvmnt |
Types of Muscle Contraction | Isometric
Isotonic |
Isometric ContrXn | Tension is developed, but angle doesn't change
Static contraction
significant amnt of T may be developed to maintain joint angle
Prevents mvmnt by external F |
Isotonic ContrXn | Tension is developed, angle changes
Dynamic contractions
Varying degrees of T in muscles result in joint angles changing
Cause or control joint mvmnt |
Concentric | type of isotonic contraction
Muscle develops tension as it shortens
Muscle developes enough F to overcome Resistance
Against gravity
Positive |
Eccentric | Muscle gradually lessens T to control descent of resistance
Muscle lengthens under T
Resistance overcome muscle contraction but muscle can still control
Mvmnt with gravity
F of muscle < R
Negative
Decelerates body mvmnt |
Isokinetics | Exercise using Concentric and/or Eccentric contractions
V of mvmnt is constant
Contraction occurs throughout the mvmnt
NOT another type of contraction
Ex- Biodex, Cybex, Lido |
Agonist Muscles | Primary moves
Cause joint motion thru specified plane when contracting concentrically |
Assistant movers or Assisters | Agonist muscles that contribute sig. less to the joint motion |
Antagonist | located on opp side of joint from agonist
Opposite concentric contraction
"Contralateral muscles"
Work in coop w/ agonist by relaxing and allowing mvmnt
Concentric contraction performs opposite joint motion of agonist |
Synergist | Assist agonists
"Guiding Muscles"
Refine mvmnt & Rule out undesired motion |
Neutralizers | Prevent undesirable movements like inappropriate muscle substitutions
Contract to resist specific actions of other muscles.
Ex- when only sup. of biceps brachii is desired, triceps brachii contracts to neutralize flexion action of the biceps brachii |
Stablizers | Surround joint
contract to fixate or stabilize area to enable another limb to move
known as FIXATORS
estab. firm base for more distal joints to work
Ex: muscles of scap and gleno contract to stabilize shoulder and humerus in bicep curl |
Force Couples | Two or more F are pulling in diff. directions on an object causing the object to rotate about its axis.
More efficient movement
Steering wheel |