Thursday, April 7, 2011

Types of muscle contractions

There are several different types of muscular contractions used while exercising. These contractions are:
-          Concentric
-          Eccentric
-          Isometric
-          Isokinetic
In this report im going to give a brief outline as to what these contractions are what movements represent each contraction.

Concentric (or isotonic) contractions are the most commonly used contraction within the gym environment. A concentric contraction in scientific terms means ‘an individual muscle shortening under resistance.’ This simply means the muscle getting smaller while lifting a weight. For example on the upward phase of a bicep curl the bicep gets smaller while lifting weight.
Concentric exercises include:
      -          Upward phase of a bench press
      -          Upward phase of a bicep curl
                                             -          Upward phase of a squat

Eccentric muscle contractions are just as common in the gym as concentric contractions.
Eccentric contractions is ‘a muscle lengthening under resistance.’ Meaning the opposite of concentric, the muscle is getting longer while holding a weight. For example the downward phase of a bicep curl the bicep muscle is lengthening while holding a weight.
On average most people are 40% stronger on the eccentric phase of any given lift. For instance its easier to longer the weight down on bench press but so much harder pressing it up.
For advance weight trainer’s eccentric muscle training is a program where the trainer only ever eccentrically lowers the weight and never concentrically lifts it. This type of training is only for advance lifters due to the fact that they are lifting more weight than they can lift concentrically.
Eccentric exercise include:
-          Downward phase of a bench press
-          Downward phase of a bicep curl
-          Running downhill or walking down stairs

Isometric contractions are rarely seen in the gym. This is because they are hard and not very practical. Isometric contractions are when ‘a muscle maintains the same length under load.’ This means that your muscles are staying the same length but are still contracting as hard as they can. Pushing against a wall is a perfect example. When you push on a wall (or any immovable object) your muscles are contracting but are staying the same length.
Isometric training is really only good for people that are always pushing against something that barely moves. For example:
-          Arm wrestling
-          Pushing in a scrum in rugby
-           Pushing your car to jump start it

Isokinetic is very similar to concentric contractions so a lot of people get confused by it. Isokinetic is “constant resistance to a particular muscle throughout the entire range of movement.’ In simple words this means that the weight is the same throughout the entire range of movement of any given exercise.
For example on a bench press the bottom third is the hardest part while the middle and the lockout (for most people) is the easiest. Isokinetic training means that the same resistance is used throughout the entire range of movement.
Exercises include:
-          Swimming
-          Any exercise on a hydraulic machine

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