I don’t want to bore you, but it’s good to know the different ways muscles contract, especially since people generally tend to think that one is harder and better for you than the rest. That’s not true. Here are the basics on contracting muscles:
Isometric: That is when you contract a muscle and hold that contraction. Like when you pull your belly button to your spine and hold it there for a set amount of time. It’s one of the reasons that Pilates is proven to be more effective at strengthening the core. When you purposefully squeeze a muscle you are using it works harder.
Concentric: This is the one more people are familiar with. It is what we call the contraction while the muscle is shrinking or tightening. So if you think of a bicep curl it is when you lift the weight up. Or, think of a roll up, your abs are contracting as you roll up. This is the type of contraction people focus on the most, but it doesn’t make it the most important.
Eccentric: This is the contraction when the muscle lengthens. So when you lower the bicep curl or, in the case of the roll up, when you lower your body back down to the floor. People have a tendency to rush through this contraction thinking it’s the easy part or using it as a break, but if you move in a slow and controlled manner as your muscle lengthens you will be getting even stronger. New research is placing more importance on the eccentric contraction.
The thing to remember is that all three forms are contractions, which means the muscle gets worked each way. No contraction is better than the other. They all help train your muscles.