Muscle Contraction is defined as the activation of tension-generating sites within muscle fibres. When we think about contracting a muscle it is quite common for people to only think about the muscle “shortening” as we flex a muscle or lift a weight – “Concentric Contraction”. However muscle tension can be generated in different ways such as when we hold a weight in the same position, meaning there is no change in the muscle length – “Isometric Contraction”.
When a muscle length changes and the tension is kept the same this is called an “Isotonic Contraction” and this type of contraction can be split down into two categories – Concentric & Eccentric.
In “Concentric Contractions” the muscle tension rises to meet/beat the resistance (Gravity/Weight) and then stays constant as the muscle shortens. In “Eccentric Contractions” the muscle lengthens due to the tension being less than the force produced by the resistance (Gravity/Weight) and its these Eccentric Contractions that we are going to be talking about today.
(An “Isokinetic Contraction” is when a muscle contracts at a constant rate of speed regardless of the tension generated… This type of training is usually done on specific Isokinetic machines that increase the load as the force is increased)
It is quite clear to see that when a muscle is being lengthened under tension, it has even greater potential to cause Micro-trauma/tears and this is why Eccentric Contractions are so associated with DOMS (Delayed Onset Muscle Soreness)
Studies have shown that working hard on the Eccentric phases of lifts can dramatically increase muscle growth by not only producing more trauma to the muscle but also stimulating greater protein synthesis & increasing the production of IGF-1 (Insulin-Like Growth Factor 1) which has anabolic (muscle building) effects. Working on Eccentric/Negative lifts can also result in much greater strength gains.
Its not just about getting from point A to point B and achieving a lift, its about all the tension in between… Try concentrating on the Eccentric phases of your lifts and see how it can progress your training.