A concentric contraction is a way of using the body's muscles for physical tasks. A concentric muscle 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.
Concentric contraction occurs when the muscle is actively countering resistance, and manipulating a weight load. When a person is doing a bicep curl, and moving the weight up and toward the chest, there is a concentric contraction in the muscles. When the person is releasing the weight, and letting it gradually fall back down, the muscle is experiencing an eccentric contraction. Eccentric contraction has to do with distributing weight passively, with the help of gravity, rather than actively manipulating the weight load.
Some activities can break down the isotonic exercise process, and focus on either concentric contraction or eccentric contraction. Many trainers and experts believe that taking a combined approach is more useful toward building and overall body capacity to handle resistance. Everyday activities like climbing up and down stairs, as well as other balanced tasks, combine both concentric and eccentric contractions.
It is generally not hard for beginners to get concentric and eccentric contractions into a fitness routine. Many gyms maintain a variety of free weights to help users practice both kinds of isotonic exercise. Dumbbells are common weight tools for doing concentric and eccentric muscle contractions. Kettlebells, medicine balls, and other free weight tools are also useful for isotonic exercise.
Many physical fitness experts would recommend combining isotonic exercise with aerobic exercise. Individual fitness participants might combine fixed weight or free weight lifting with using treadmills, elliptical machines, rowing machines, stationary bikes, or other aerobic training equipment. This combined fitness schedule can help get individuals the cardiovascular benefits of an elevated heart rate, as well as the muscle growth that comes with concentric and eccentric muscle contractions.