Muscle Soreness - Eccentric Contraction

We have all felt that muscle soreness feeling a day or so after training yet many of us do not know what it is and what impact it is having on our body.

The official term for this muscless soreness is actually "Delayed onset muscle soreness", it is called this because the soreness can occur up to three days after training. The sore feeling that occurs can be local to the area you have trained (the chest after bench pressing for example) or can be felt on multiple muscle groups (back and legs after deadlifts for example).

Scientists previously thought this sore feeling was due to a build up in lactic acid within the muscles that were trained but this theory has been pushed aside by a new theory on muscle soreness. The reason that this theory does not hold and was pushed aside is because lactic acid does not last long in a specific area and disperses not long after exercise.

The new theory is that the muscle soreness a weight trainer (powerlifter or bodybuilder) may feel is due to pushing the body slightly further than the accustomed training levels it is used to. This causes tiny tears in the muscle fibres through something called eccentric contraction.

What is Eccentric Contraction?

When lifting a weight that produces greater force than that of the muscle lifting it (in laymans terms lifting heavy weights you find difficult to lift) the tension causes the muscle to elongate.

What this means is that as you're lifting a weight your muscle is not only lifting the weight. By elongating itself the muscle is acting as a decelerate for the joint so towards the end of your lifting movement the joint is not pulled by the muscle contraction, but rather protected as the muscle controls how you position the weight.

Example: Squat

When you have moved in to the squat position then move to stand up again your muscle elongates towards the end of the movement to compensate for the heavy load you are lifting and act as a decelerate for the joints to stop them being pulled in the direction of the muscle contraction.

When muscles are put under extensive eccentric loading, as caused by weight lifting, small tears occur in the muscle fibres which causes your muscle soreness.

What does this mean to me?

What this means is that the soreness you are feeling is positive as you have pushed your body and now it is going to repair stronger, in essence this is what a weight lifter is trying to achieve. Every time you train you are tearing your muscles slightly and they rebuild stronger.

What this does mean is that you should not train the muscle group that is sore until the soreness subsides as you could overtrain causing a negative impact on the muscle. This means breaking up your training schedule to compensate (train one day, have a day off the next for example).

When you first start weight lifting in the gym you will expect to feel sore for the first few times you train as your muscles gets used to the movements you are doing. Over time you will not feel the soreness as much as the muscles know the movements so will not get delayed onset muscless soreness through eccentric contraction so easily.