Sensible advice for aches, pains & injuries

Eccentric Contraction

A weird bit of muscle physiology

updated (first published 2007)
by Paul Ingraham, Vancouver, Canadabio
I am a science writer and a former Registered Massage Therapist with a decade of experience treating tough pain cases. I was the Assistant Editor of for several years. I’ve written hundreds of articles and several books, and I’m known for readable but heavily referenced analysis, with a touch of sass. I am a runner and ultimate player. • more about memore about


An eccentric or braking contraction is an interesting but routine type of muscular contraction that seems like a paradox: the muscle is contracting even as it is lengthening! Eccentric contraction is a bit physiologically mysterious, and is known to be harder on muscle, causing more soreness (quadriceps after hiking down a mountain is the classic example) — a good stimulus to adaptation, in tendon as well as muscle.

full article 650 words

When you think of a muscle contraction, you think of a muscle getting shorter, which is called “concentric” contraction — but that’s not always what happens. In fact, your muscles routinely have to pull off a trick known as “eccentric” contraction, and it is odd: contraction while lengthening, also sometimes called a braking contraction.

concentric contraction = contraction while shortening
eccentric contraction = contraction while lengthening?!

How is this possible? How can that even be called a “contraction”?

Good question! This is one of the classic examples of a small but persistent mystery of biology. In this age of science fiction body scans and custom-built medicinal molecules, no one really knows quite how eccentric contraction works. The dominant theory of muscle contraction — the sarcomere model — cannot quite explain it.

What is an eccentric contraction used for?

Even if no one knows how it works, it’s easy to understand why you need eccentric contraction: we regularly need to control, slow-down the lengthening of a muscle, a “braking” contraction.

The simplest example of an eccentric contraction is lowering a barbell in a biceps curl. Obviously the biceps muscle contracts to lift the barbell up. But it’s also contracting as you lower the weight — if it weren’t, you would drop it pretty fast! The contraction is not quite strong enough to stop the lengthening of the muscle. The contraction is just strong enough to put the brakes on the lengthening of the muscle.

Here are three sneakier, less obvious examples:

Notice that all three of these examples correspond to body parts that tend to get sore after exercising. Your shins hurt after your first hard-surface run in a while, your quadriceps hurt after climbing down a mountain, and the back of your forearm hurts after your first couple tennis games of the year.

Eccentric contraction hurts!

Other than intellectual interest, this is why you should care about eccentric contractions: because they hurt more!

Anyone who has ever exercised knows about that nasty feeling you can get in your muscles. Usually it’s worst the day after, sometimes two days after. It feels like your muscles have been bruised inside and out. If it’s bad enough, it’s like you can feel individual molecules of air bashing into your skin. The muscle is weak and incredibly sensitive to contraction until you recover.

This phenomenon is called delayed onset muscle soreness (DOMS) … and it’s much worse in muscles that have been worked hard eccentrically. That’s why your shins are sore after running hard on concrete, why your quadriceps are sore after climbing down a mountain, and why your forearms are sore after your first tennis match in a year.

Although concentric contraction can also cause DOMS, eccentric contractions are much worse. And — again — no one knows why. There’s no cure for it except to get it over with! Because no one really understands DOMS… although that may finally be starting to change, just in the last few years. For more information, see Post-Exercise, Delayed-Onset Muscle Soreness: The biology & treatment of “muscle fever,” the deep muscle soreness that surges 24-48 hours after an unfamiliar workout intensity

About Paul Ingraham

Headshot of Paul Ingraham, short hair, neat beard, suit jacket.

I am a science writer, former massage therapist, and I was the assistant editor at for several years. I have had my share of injuries and pain challenges as a runner and ultimate player. My wife and I live in downtown Vancouver, Canada. See my full bio and qualifications, or my blog, Writerly. You might run into me on Facebook or Twitter.

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