Lecture 1: Biomechanics Flashcards
Why is a pushing force actually a pulling force?
Muscles only pull on tendons and tendons only pull on muscles. Tendon pulls the the ligament even though it may seem like a push. Triceps active Biceps: inactive
Muscle as a pulling force
Triceps inactive
Biceps: active
Anatomical Plane
sagittal
transverse
coronal/frontal
Anatomical Axis
frontal
sagittal
vertical
(be able to draw)
Cartwheel through…
- frontal plane
- sagittal axis
360 through
- transverse plane
- vertical axis
origin
- attachment of a muscle tendon to the stationary bone
- usually proximal
insertion
- attachment of a muscle tendon to teh movable bone
- usually distal
agonists
contraction is primarily responsible for a particular movement
-prime movers
synergists
helper to the agonist
- usually at the start
- also help stabilize origin of agonist
antagonist
actions oppose the agonist
-stabilizes agonist action
pitching
- agonist=triceps
- antagonist= biceps (slows and controls the movement)
lever
a rigid or semi-rigid body that when subjected to a force whose line of action does not pass through its pivot pointe exerts force on any object impeding its tendency to rotate
Torque
magnitude of force times the length of its moment arm
Mechanical Advantage
-ratio of Maf to Mrf
MA greater than 1
allows the Fa to be less than the Fr to produce an equal amount of torque
MA less than 1
is a disadvantage in the common sense of the term (at which most levers of the body act)
-sacrifice power but increase ROM
First Class Lever
The forearm
Fm Fulcrum Fr
-typically produces disadvantage
Second Class Lever
body acts as a 2nd class lever Fm Fr Fulcrum ex) calf raise- fulcrum=ankle applied force=calf
Third Class Lever
*most common lever in the body
Fulcrum Fm Fr
mechanical disadvantage
Changes in Mechanical advantage
- most of the skeletal muscles operate at a considerable mechanical disadvantage
- during sporst and other physical activities, forces in teh muscles and tendons are much higher than those exerted by the hands or feet on external objects or the ground
Bicep Curl
- not consistent all the way through
- increase length of moment arm with tendon insertion a bit further away
- change in the moment arm which is then going to affect muscle torque
- larger moment arm when muscle is attached further away from the joint
Patella
structure in place to help decrease the disadvantage throughout the ROM
- keeps the moment arm the same
- increase force of quad
In a bicep curl where is the resistive force the greatest?
middle because the moment arm is the longest
Moment of failure
- usually just before 90 degrees or at the bottom (aka sticking point) where you must overcome inertia
- usually more of a free weight thing
Supporting the vertebral column during lifting
-ned to keep the spine in line to prevent compression on either side.
Fluid ball
process of keeping the abdominal area tight to aid in supporting the vertebral column during resistance training
-engaging the core section
valsalva manoeuvre
holding everything tight and not being able to move
why use it? should be able to lift more weight
