Type I muscle fibers are involved in endurance activities. These fibers, also called slow twitch fibers, are noted for their ability to produce energy in the presence of oxygen. Thus, they are primarily aerobic. The main fuel source for this fiber is fats (fatty acids), which allow the muscle to work at a steady rate with noticeable resistance to fatigue. Their color is typically quite red, a result of the high content of "myoglobin", an iron-containing protein that stores and delivers oxygen. Slow twitch fibers are not noted for their speed, their anaerobic capacity, or their ability to contract at a fast rate repeatedly, but rather their indefatigability and aerobic capacity.
Was this article helpful?
Achieve the Fitness and Wellness for You that you have always wanted by learning the facts so you can take the right steps to maximize your health. Learn How to Achieve Real Fitness and Wellness for a Healthy Body, Mind and Spirit to Improve Your Quality of Life in Today's World. Receive Valuable Information to Discover What Really Matters and What Actually Works in Finding Genuine Wholeness for All Aspects of Your Being