Investigatory Project

Dynamic contraction
Dynamic contraction refers to a contraction where movement is involved. An example is lifting of a dumbbell from either side to the shoulder. Static contraction, on the other hand, refers to a contraction where no movement is involved.

Concentric and Eccentric
A concentric contraction is a way of using the body's muscles for physical tasks. A concentricmuscle contraction is a very common kind of muscle contraction. It is part of many basic physical exercises and everyday activities.
Professional trainers, physical therapists and others often talk about concentric contractions when they are explaining the different types of contractions that muscles achieve. Concentric contractions are as part of what experts call isotonic exercise. In isotonic exercise, a weight load or resistance remains constant through a range of motion.
A simple way to think of isotonic exercise is in fixed weight or free weight lifting. Either of these are good examples of isotonic exercise. Another simple example is someone picking an item up off of a table and putting it back down. In all of these examples, the weight load on the body is constant.
Isotonic exercise generally includes two kinds of muscle contractions. The first kind is concentric contraction, which some experts call "active shortening" of muscles. The second kind is known as eccentric contraction, or "active lengthening" of muscles.

Static contraction
Contraction in which opposing muscles contract against each other and prevent movement. Fixation action of a muscle in a static contraction is termed isometric, because it develops tension without changing length.