Throughout my series on the basic movement patterns I made mention of eccentric, concentric and isometric muscle contractions. This article looks at these muscle contractions in a little more detail to help you get a better understanding of which muscles are involved and how they are working while you exercise.

Eccentric and concentric muscle contractions are known as isotonic contractions because they result in movement. During these contractions the muscle will change length and depending and the joint it acts on will move.

A concentric muscle contractions is generally the working phase of an exercise, the muscle is shortening in order to lift a load, be it your body weight or a limb, a dumbbell or anything else you are trying to move. During the concentric phase you are working against gravity.

The eccentric phase of an exercise is often called the negative or down phase. During an eccentric muscle contraction the muscle lengthens. We are roughly 150 per cent stronger eccentrically than we are concentrically due to the contribution of gravity.  When you hit a plateau eccentric training can be an effective way to break through the plateau. In my next blog I will discuss how eccentric training works and when and how to add it to your training.

During  an isometric muscle contraction the length of the muscle does not change and the joint stays still.  When an exercise is performed with correct technique there are usually numerous muscles working isometrically. Plank is an example of a purely isometric exercise. During a chin-up, the forearm muscles are generally isometrically contracted.

References

Higbie, E.J., Cureton, K.J., Warren, G.L. & Prior, B.M. (1996). Effects of eccentric and concentric training on muscle strength, cross-sestional area and neural activation. Journal of Applied Physiology, 81:(5) 2173-2181.