Difference Between Concentric and Eccentric Contractions

Thekey differencebetween concentric and eccentric contractions is thatconcentric contraction causes muscles to shorten while eccentric contractions cause muscles to elongate.

Muscle contraction is a complex process which changes the length of the米uscle fibers. Muscle fibers generate tension. It involves the interaction between contractile proteinsactin and myosinin the presence of calcium. There are different types of muscle contractions based on the changes in the length of the muscle during contraction.Isometric and isotonic是两种主要类型。等渗收缩通过改变肌肉的长度而产生力，而等距收缩会产生力而不改变肌肉的长度。等渗收缩分为两种类型，为同心和偏心收缩。

内容

1.Overview and Key Difference
2.什么是同心收缩
3.What are Eccentric Contractions
4.Similarities Between Concentric and Eccentric Contractions
5.并排比较 - 表格形式的同心和偏心收缩
6.概括

什么是同心收缩?

Concentric contraction is a type of isotonic contraction which causes muscles to shorten while generating a force. Concentric contraction occurs throughout the muscle in the direction of contraction of a muscle. These contractions are required when lifting a load. For instance, when lifting a heavy load, a concentric contraction of the biceps causes the arm to bend at the elbow. During the concentric contraction, cross-bridge cycling occurs in order to produce the force.

A sarcomere is the functional unit of a muscle fiber. It contains both thin actin filaments and thick myosin filaments. When the muscle fiber is activated by a nerve impulse and calcium ions, the filaments, actin and myosin, move relative to each other to produce shortening of the sarcomere, muscle fiber and the whole muscle.

What are Eccentric Contractions?

Eccentric contraction is a type of muscle contraction which causes muscles to lengthen. It occurs in response to a greater opposing force which is higher than the force generated by the muscle. Therefore, they occur against or in the opposite direction of contraction of a muscle. Eccentric contractions mostly decelerate the muscle joints. These contractions also can alter the position of the load force.

Eccentric contractions can be voluntary or involuntary. During eccentric contractions, cross-bridge cycling occurs to control the extension of the muscle even though the sarcomere, muscle fiber, and muscle are lengthening.

What are the Similarities Between Concentric and Eccentric Contractions?

• In both concentric and eccentric contractions, length of the muscle changes.
• 他们产生力量。
• Strength training involves both eccentric and concentric contractions.
• 在这两个收缩中，都会发生跨桥骑自行车。

What is the Difference Between Concentric and Eccentric Contractions?

Concentric contraction is a type of muscle contraction that permits the muscle to shorten. In contrast, eccentric contraction is a type of contraction that causes muscle lengthening. So, this is the key difference between concentric and eccentric contractions. During concentric contraction, sarcomere, muscle fiber, and the muscle shorten while during eccentric contraction, they lengthen.

Below infographic tabulates the differences between concentric and eccentric contractions in more detail.

概括– Concentric vs Eccentric Contractions

同心和偏心收缩是两种类型的等渗肌肉收缩。同心收缩会导致肌肉缩短，而偏心收缩会导致肌肉的延长。因此，这是同心收缩和偏心收缩之间的关键区别。肌膜，肌肉纤维和肌肉在同心收缩期间缩短。相比之下，肉眼，肌肉纤维和肌肉在偏心收缩中延长。

Reference:

1. “Types Of Muscle Contractions: Isotonic And Isometric | Lifetime Fitness And Wellness”. Courses.Lumenlearning.Com, 2020,Available here.
2.“肌肉生理 - 收缩类型”。Muscle.ucsd.edu，2020年，Available here.

Image Courtesy:

1.通过OpenStax–(CC BY 4.0)viaCommons Wikimedia

2. “Sarcomere” By David Richfield (User:Slashme) Richfield, David (2014). "Medical gallery of David Richfield". WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.009. ISSN 2002-4436. – Own work(CC BY-SA 3.0)viaCommons Wikimedia