Eccentric Contraction Of A Muscle
An eccentric contraction is the motion of a muscle while it is lengthening under load, where the muscle contracts to control joint motion performed by an outside force.
An example of an eccentric contraction is when performing an exercise such as 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 slowly 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 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.
Types Of Muscle Contractions
There are three distinct phases in the movement of muscles and tendons. An eccentric contraction is one of the three phases, where as the other two are called an isometric contraction and a concentric contraction. Basic definitions of the three listed phases are:
This is 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 compared to an eccentric contraction is that with a concentric contraction the muscle shortens as it contracts. An example using the previously discussed bicep curl would be that the concentric phase of this muscle contraction is when the elbow flexes moving the hand from the leg towards the shoulder.
As previously discussed above an eccentric contraction is the motion of muscle while it is lengthening under load and 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.
Also referred to as isometric exercises or isometrics are 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 dynamic through a range of motion as eccentric and concentric contractions are performed.
An example of an isometric contraction is if when performing a calf raise and lifting your heel/s off the ground you hold the contraction at the top of the movement. Meaning you have a concentric contraction as you rise up onto your toes and then and isometric contraction at the top of the movement as you hold the position on your toes, followed with a eccentric contraction of the calf muscle 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 on What Is An Eccentric Contraction? should consult his or her physiotherapist, personal trainer or otherwise appropriately skilled practitioner.