Biology 105
Biology of Exercise
Spring 2003

2/28/03 - Post-class outline

Learning objectives:

Are all muscle fibers the same? How do they differ?

 

Diagrams.

• Anaerobic and aerobic metabolism during sustained exercise
• Table of energy metabolism
• UCSD site on muscle physiology (external link)
• Table of fiber types in different athletes
• Table of human myosin isoforms

Muscle types

• In many muscles, distinctly different cell (fiber) types can be identified.

• SO - slow-twitch oxidative - Type I
• Low power
• Fatigue resistant
• Lots of mitochondria
• Fewer contractile filaments
• Relatively low contraction velocity
• FOG - fast-twitch oxidative/glycolytic - Type IIa.
• Intermediate power and fatigue resistance.
• Intermediate contraction velocity
• FG - fast glycolytic - Type IIb
• High power
• Fatigue easily
• Few mitochondria
• Many contractile filaments
• Fast contraction velocity

• Determination of fiber type
• Endurance athletes have more Type I fibers than sprinters - table.
• Training can alter the relative amounts of Type I vs. Type II fibers.
  • endurance and resistance exercise promote shift from Type II to Type I.
  • mechanism of training effect
    • expression level of proteins
    • expression of protein isoforms - table.