TYPES OF MUSCLE CONTRACTION

ISOKINETICS

- A TYPE OF DYNAMIC EXERCISE USING CONCENTRIC AND OR ECCENTRIC MUSCLE CONTRACTIONS - SPEED (OR VELOCITY) OF MOVEMENT IS CONSTANT - MUSCULAR CONTRACTION (IDEALLY MAX CONTRACTION) OCCURS THROUGHOUT MOVEMENT - NOT ANOTHER TYPE OF CONTRACTION, AS SOME HAVE DESCRIBED - EX: BIODEX, CYBEX, LIDO

ISOMETRIC CONTRACTION

- ACTIVE TENSION IS DEVELOPED WITHIN MUSCLE BY JOINT ANGLES REMAIN CONSTANT - STATIC CONTRACTIONS - SIGNIFICANT AMOUNT OF TENSION MAY BE DEVELOPED IN MUSCLE TO MAINTAIN JOINT ANGLE IN RELATIVELY STATIC OR STABLE POSITION

ISOTONIC CONTRACTION

- INVOLVE MUSCLE DEVELOPING ACTIVE TENSION TO EITHER CAUSE OR CONTROL JOINT MOVEMENT 1. DYNAMIC CONTRACTIONS 2. THE VARYING DEGREES OF TENSION IN MUSCLES RESULT IN JOINT ANGLES CHANGING *** EITHER CONCENTRIC OR ECCENTRIC ON BASIS OF WHETHER SHORTENING OR LENGTHENING OCCURS

CONCENTRIC CONTRACTIONS

- MUSCLE DEVELOPS ACTIVE TENSION AS IT SHORTENS - OCCURS WHEN MUSCLE DEVELOPS ENOUGH FORCE TO OVERCOME APPLIED RESISTANCE - CAUSES MOVEMENT AGAINST GRAVITY AND RESISTANCE - DESCRIBED AS BEING A POSITIVE CONTRACTION - ACCELERATES MOVEMENT - FORCE DEVELOPED BY THE MUSCLE IS GREATER THAN THAT OF THE RESISTANCE - RESULTS IN JOINT ANGLE CHANGING IN THE DIRECTION OF THE APPLIED MUSCLE FORCE - CAUSES BODY PART TO MOVE AGAINST GRAVITY OR EXTERNAL FORCES

ECCENTRIC CONTRACTIONS

- MUSCLE LENGTHENS UNDER ACTIVE TENSION - OCCURS WHEN MUSCLE GRADUALLY LESSENS IN TENSION TO CONTROL THE DESCENT OF RESISTANCE - WEIGHT OR RESISTANCE OVECOMES MUSCLE CONTRACTION BY NOT TO THE POINT THAT MUSCLE CANNOT CONTROL DESCENDING MOVEMENT - DECELERATES MOVEMENT - CONTROL MOVEMENT WITH GRAVITY OR RESISTANCE - DESCRIBED AS NEGATIVE CONTRACTION - FORCE DEVELOPED BY THE MUSCLE IS LESS THAN THAT OF THE RESISTANCE - RESULTS IN JOINT ANGLE CHANGING IN THE DIRECTION OF THE RESISTANCE OR EXTERNAL FORCE - CONTROLS BODY PART TO ALLOW MOVEMENT WITH GRAVITY OR EXTERNAL FORCES - USED TO DECELERATE BODY SEGMENT MOVEMENT - MUSCLE ACTION BECAUSE IT IS LENGTHENING

WITHOUT MUSCLE CONTRACTION

- REFERRED TO AS PASSIVE - SOLELY DUE TO EXTERNAL FORCES SUCH AS THOSE APPLIED BY ANOTHER PERSON, OBJECT, RESISTANCE OR THE FORCE OF GRAVITY IN THE PRESENCE OF MUSCLE RELAXATION

CONTRACTION

- WHEN TENSION IS DEVELOPED IN A MUSCLE AS A RESULT OF A STIMULUS - CAN BE USED TO CAUSE, CONTROL, AND PREVENT JOINT MOVEMENT OR 1. TO INITIATE OR ACCELERATE MOVEMENT OF A BODY SEGMENT 2. TO SLOW DOWN OR DECELERATE MOVEMENT OF A BODY SEGMENT 3. TO PREVENT MOVEMENT OF A BODY SEGMENT BY EXTERNAL FORCES - ALL MUSCLE CONTRACTIONS ARE EITHER ISOMETRIC OR ISOTONIC