4 types of exercise contractions
There are many types of exercise to choose from which all have their own benefits. What's common among all is they require some form of muscular contraction. There are four different types of muscle contraction.
Isotonic
Eccentric
Isometric
Isokinetic
Isotonic
All lifting exercises require Isotonic contractions. This happens when the muscle shortens as it contracts. An example of isotonic contraction can be seen when we flex the bicep muscle. Stand with one arm straight and the palm of the hand facing up. Roughly measure the length from the start of the biceps muscle to the point where it meets the shoulder. Now curl the hand towards the shoulder, the biceps muscle shortens as it contracts. When you reach the end point take another rough measurement of the biceps again, it will be much shorter.
Another example are the triceps muscle (opposite of biceps). Do the same experiment again this time measure the triceps and start at the curled position. The triceps shortens as the arm straightens.
Other examples are....
lifting objects above the head - front shoulder (anterior deltoid) shortens
lifting object up from lying position - chest muscle shortens
lifting body up from squat position - quadriceps muscle shortens as legs extend
doing a sit up
throwing a ball
swinging a bat
In fact Isotonic contractions are the most common, many exercises and activities involve this type of contraction. To learn why muscles shorten during an Isotonic contraction click on the next link!
Eccentric
Eccentric contraction is the opposite of isotonic, the muscle lengthens as it gains tension. These are much less common and not as beneficial as the common Isotonic. An example is when someone manages to pull your arm straight while at the same time you are try to keep the arm locked in one position. In other words, the load is too great!
Other examples are...
running downhill
walking downstairs
landing on the ground from a jump
This type of contraction is not recommended!
Isometric
An Isometric contraction happens when there is tension on the muscle but no movement is made causing the length of the muscle to remain the same. This type of contraction is also referred to as a static contraction. Some bodybuilders make up their own exercises using Isometric contraction in order to develop strength, an example is when I seen someone attempt to curl one arm using equal resistance from the other arm.
attempting to lift an immoveable object
holding a weight at arm's length
some wrestling movements
The above examples are advanced forms of exercise and should not be attempted!
Isokinetic
Similar to the Isotonic contraction, the Isokinetic contraction causes the muscle to shorten as it gains tension. The difference is Isokinetic requires a constant speed over the entire range of motion, therefore this type of contraction require special equipment to exercise properly. An example is an arm stroke when swimming, the even resistance from the water offers a constant speed.
Ankle weights benefits for losing weight while exercising