Basic concepts in KinesiologyMontakarn Chaikumarn, PhD

DefinitionKinesiology Kinesis = to moveOlogy = studythe science of human movement Kinesiologists assess human movement, performance, and function by applying the sciences of biomechanics, anatomy, physiology, and motor learning.

Kinetics, Kinematics

Scope of practice The practice of Kinesiology is the assessment of movement, performance, and function; and the rehabilitation, prevention, and management of disorders to maintain, rehabilitate, and enhance movement, performance, and function in the areas of sport, recreation, work, exercise, and activities of daily living

A kinesiological approach applies scientific and evidence based medical principles towards the analysis, preservation and enhancement of human movement.

Limited definition of kinesiologythe study of human motion by focusing on the anatomic and biomechanical interactions within the musculoskeletal system

Biomechanical studyStaticsDynamicsKinematicsKinetics

Kinematics position, velocity, acceleration

Kinetics Types of forces: Non-contact forces (law of gravitation, weight)Contact forces (ground reaction force, joint reaction force, friction, fluid resistance, inertial force, muscle force )

(Angular or Rotary motion) (Linear motion) RectilinearCurvilinear

Translation- RotationTranslationRotation

Translation - RotationTranslatory motionA motion in which all parts of a moving body move toward the same direction.Linear motionCurvilinaer motionCircular motion

Translation - RotationRotary motionA motion in which the object act as a radius and all parts of the moving object rotate in a same angular direction and follow a circular path about a pivot jointAngularSpin

Angular motion

Linear motion

OsteokinematicsOsteokinematicsDescribe the motion of bones relative to 3 cardinal (principal) planes of the bodySaggital planeFrontal planeHorizontal plane

OsteokinematicsPlane of motion cardinal plane: 3 imaginary perpendicular reference planes that divide the body in half by mass.

Saggital: left-rightFrontal (Coronal): front- back Horizontal (Transverse): upper- lower Anatomical position

Movements in sagittal plane

Movements in Frontal plane

Movements in Transverse plane

OsteokinematicsAxis of rotation Bones rotate about a joint in a plane that is perpendicular to an axis of rotation.

Example:Shoulder allow movement in all 3 planes3 axis of rotation

OsteokinematicsAnatomical axesWhen a segment of human body moves, it rotates around an imaginary axis of rotation that passes through a joint. 3 reference AxesMediolateral axis (ML)Anteroposterior axisLongitudinal axis

Osteokinematics3 reference AxesAnteroposterior axis (X)Perpendicular to the frontal planeLongitudinal axis (Y)Perpendicular to the transverse planeMediolateral axis (Z)Perpendicular to the sagittal plane

Anteroposterior axisLongitudinal axisMediolateral axis

OsteokinematicsDegree of freedom (DOF)The number of independent movements allowed at a joint.The number of permitted plane in which the segment move.The number of the primary axes which the segment possess.

Example:Shoulder has 3 degrees of freedom, 1 for each plane Wrist has 2 degrees of freedom

Degree of Freedom of motionOne degree of freedom ( 1DOF) 1 Two degree of freedom (2DOF) 2 Three degree of freedom (3DOF) 3

OsteokinematicsMatter of PerspectiveMovement at a joint can be considered from two perspectives.

Proximal segment can rotate against the relatively fixed distal segmentDistal segment can rotate against the relatively fixed proximal segment.

Knee flexion Relative motion between thigh and legTibial-on-femoral / femoral-on-tibial perspective

Kinematic chainOpen kinematic chainClosed kinematic chain Kinematic chain = a series of articulated segmented links, such as the connected pelvis, thigh, leg and foot.

ArthrokinematicsArthrokinematics The motion that occur between articular surfaces of joints

Concave ConvexMost joint surfaces are curved with one surface being relatively convex and one relatively concave.

ArthrokinematicsFundamental movement between joint surfaces RollSlideSpin

convex surface move on concave surface convex concave

ArthrokinematicsRoll-and-slide movementBone rotates through space is by a rolling of its articular surface against another bones articular surface.

Example: Glenohumeral jt. Abduction- Convex-on-concave movement- Convex humeral head against concavity of glenoid fossa.

Arthrokinematics

The convex member rolls and slide in opposite direction.Concave-on-convex movement slide in similar direction

ArthrokinematicsSpinA bone rotate by a spinning of its articular surface against the articular surface of another bone.

Example: 1.PronationRadius spin against capitulum of humerus. 2. Starting at 90 abducted GH jt. Internal-External rotation

Spin

Roll

Slide

ArthrokinematicsMotions that combined roll-and-slide and spin arthrokinematics

Example:Knee flexion-extensionFemoral-on-tibial knee extension femur spins internally slightly, femoral condyle rolls and slide relative to fixed tibia.

ArthrokinematicsClose-packed position The pair of articular surfaces fit best in only one position, usually in or near the very end range of a motion. In this position, most ligaments and part of capsule are pulled taut stability to jointAccessory motion are minimal.

ExampleKnee: close-paced position full extension (standing)Provide stability to knee.

ArthrokinematicsLoose-packed positionIn this position, ligaments and capsule are relatively slackened, allowing an increase in accessory movement.

ArthrokinematicsThe joint is generally least congruent near its mid range.Close-packed position one position of best fit in area of contact between the articulating bone surface is maximum.Knee, wrist, IP extension/ ankle dorsiflexionLoose-packed position reduction of area of contact between the articulating bone surfaces.

Take a brake

Kinetic Concepts for Analysing Human Motion

Newtons Law of MotionLaw of Inertia, F = 0 V = Velocity (m/s)Law of Acceleration, F = ma F= Force (N), m = Mass (kg), a = Acceleration (m/s2)Law of Reaction,Faction = Freaction

TorqueRotary effect of a force

Torque (N-m) = Fd ;F = Force (N) d=Perpendicular Distance (m)

the 80 kg (800 N) boy 2 m from the fulcrum (center of gravity) balances his 40 kg (400 N) sister 4 m from the fulcrum(800 x 2) N-m = (400 x 4) N-m

Archimedes and the Law of the Lever

"Magnitudes are in equilibrium at distances reciprocally proportional to their weights."

GIVE ME A PLACE TO STAND AND I WILL MOVE THE EARTH

LeversSimple machine consisting of a rigid bar pivoted on a fixed point and used to transmit force, as in raising or moving a weight at one end by pushing down on the other.

First-Class LeversSeesaw is an exampleCenter fulcrum between applied force and resistanceForce and resistance are balanced

SecondClass LeversWheelbarrow is an exampleCenter resistance between applied force & fulcrumA small force moves a large weight

Third-Class LeversMost common levers in the bodyCenter applied force between resistance & fulcrumGreater force moves smaller resistanceMaximizes speed and distance traveled

Vector

Vector Resolution+==+=++=0

Vector Resolution=+=+=+=+,,,,yxyxyxyx

=;

Force and MomentForce (F)a force is defined as a push or pull that results from physical contact between two objects.

Force and MomentMoment (M)a moment (M) is typically caused by a force (F) acting at a distance (r) from the centre of rotation of a segment.A moment tends to cause a rotation and is defined by the cross product function: M= r (F)

Centre of Gravity and StabilityCentre of Gravity- the point at which all of the weight of that body can be thought to be concentrated, and it depends on a bodys shape and mass distribution.

- The centre of gravity of the human body in the anatomical position is approximately at the level of the second sacral vertebra(S2).

- For motions in which the acceleration is negligible, it can be shown with Newtons first law that the centre of gravity must be contained within a persons base of support to maintain stability.

(Equilibrium)Static equilibriumDynamic equilibrium

(base of support) semicircular canal

Centre of Gravity and Stability

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