What Is An Eccentric Contraction?

What Is An Eccentric Contraction?

Eccentric Contraction Of A Muscle

An eccentric contraction is the motion of a muscle lengthening under load. Where the muscle contracts to control joint motion performed by an outside force.
Examples of an eccentric contraction, or eccentric phase of a contraction is when performing the following exercises: 

  • A biceps curl. With this exercise the action of lowering the weight back down from the “lift” is the eccentric phase of that movement. This is an eccentric contraction of the biceps as long as the dumbbell is lowered purposefully. Instead of letting the weight “drop” uncontrolled. Meaning the biceps muscles are in a state of contraction, helping to control the rate of descent of the weight.
  • Another example of an eccentric phase of a muscle contraction is; when performing a standing calf raise (heel raise) your calf muscle actively shortens to help you rise onto your toes. On the way back down, the lowering phase, your calf muscle lengthens to control your descent. This lowering phase of the movement is an eccentric contraction under the load of your body weight.

Types Of Muscle Contractions

There are three distinct phases in the loading of muscles and tendons. An eccentric contraction is one of the three phases. Where as the other two types of tissue loading are called an isometric contraction and a concentric contraction. The basic definitions of these three listed phases are:

Concentric Contraction

A contraction where the muscle force and tension created exceeds the load opposing the contraction. As such the muscle working shortens as it contracts. The key component when compared to an eccentric contraction, is that with a concentric contraction the muscle shortens as it contracts. An example is using the previously discussed bicep curl, the concentric phase of this muscle contraction is when the elbow flexes. The action of moving the hand from being down by the thigh, up towards the shoulder.

Eccentric Contraction

As previously discussed above an eccentric contraction is the motion where the muscle fibers are lengthening under load. The muscle contracts to control joint motion performed by an outside force.
Both eccentric and concentric contractions are considered to be dynamic contractions. Also referred to as isotonic movements.

Isometric Contraction:

Also referred to as isometric exercises, or isometrics. This is a type of muscle contraction where the joint angle and muscle length do not change during contraction. Isometric contractions are performed in static positions, rather than being a dynamic through range of motion contraction. The major point of difference from an eccentric, or concentric contraction.
An example of an isometric contraction is if when performing a calf raise and lifting your heel/s off the ground. The isometric part of this calf raise is holding the contraction at the top of the movement. Meaning that you perform a concentric contraction as you rise onto your toes. Then an isometric contraction at the top of the movement as you hold the position on your toes. Followed with an eccentric phase of the calf muscle loading as you slowly control the movement going from your toes, back down to the floor.

Disclaimer: Sydney Physio Clinic provides this information as an educational service and is not intended to serve as medical advice. Anyone seeking specific advice or assistance should consult their physiotherapist, personal trainer or otherwise appropriately skilled practitioner.