Slide #18

• Fibers with more inherent ATPase activity in their myosin can act faster.
• Faster fibers called FAST TWITCH or WHITE FIBERS (as compared to slow twitch fibers):
• Increased ATPase activity
• More sarcoplasmic reticulum
• More T-Tubules
• SLOW TWITCH or RED FIBERS:
• More mitochondria
• More myoglobin
• Smaller Diameter