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:. Published: July 5, 2004 / Author: Welloria Team

Muscles: Bulk or Tone?

Working out regularly enhances your muscles in one of two ways – by giving a firm tone or by adding bulky mass. Distinct sets of nutritional guidelines apply to those who want the tone and those who want the bulk. In terms of activity, bulking and toning exercises are so different from one another that they even recruit and affect separate muscle fibers.


Muscle Fibers and Activity

The slow twitch fibers are used and developed for toning purposes, while the fast twitch fibers are for bulking. Most muscles are made of a combination of the two types (except the soleus muscle in the lower leg and muscles in the back that predominantly consist of slow twitch fibers, and the fast twitch fiber muscles that move the eyes).

Since fast twitch fibers contract quickly and get tired rapidly, they are not used for long periods of activity. These fibers are white in color because they draw on glycogen for energy and do not rely on an oxygen-rich blood supply. When you suddenly jump to catch a ball, you utilize your fast twitch muscle fibers.

On the other hand, when you perform prolonged activity, like jogging for 30 minutes, you automatically use your slow twitch fibers. These fibers contract slowly and can endure long periods of exercise. Concentrated areas of slow twitch fibers have a red appearance because they contain a lot of blood vessels and use oxygenated blood to produce energy.

Studies show that both types of fibers gro... Sign-up Above to Read More!

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