Skeletal muscles consist of different types of muscle fibers.
Specific types: Type 1, Type 2A, and Type 2X (in humans).
Type 2B is found in other animals.
Type 1 Muscle Fibers: Slow Oxidative (Red)
Structural Characteristics
Diameter: Smallest among muscle fibers.
Capillary Density: High; rich blood supply gives a red hue.
Mitochondria: Abundant, essential for ATP production.
Metabolic Characteristics
Energy Production: Mainly via aerobic cellular respiration.
Utilizes glucose, amino acids, and fats.
Requires oxygen; produces ATP through oxidative phosphorylation.
Myoglobin Content: High.
Myoglobin temporarily stores oxygen, aiding in ATP production.
Functional Characteristics
Contractile Speed: Slow contraction rate due to decreased myosin ATPase activity.
Results in slow detachment and attachment of myosin heads.
Fatigue Resistance: High endurance; can sustain activity for hours.
Slow contraction and high ATP production contribute to this.
Power Output: Low; generates little power.
Recruitment
Order: First to be recruited even though they produce less power.
Efficient for activities not requiring heavy loads.
Energy Storage
Main Storage: Triglycerides.
Used in beta-oxidation to produce ATP.
Applications
Activities: Suitable for endurance activities like marathon running.
Provide continuous ATP supply and high fatigue resistance.
Posture: Important in maintaining posture against gravity (anti-gravity muscles).
Summary
Type 1 fibers, or slow oxidative fibers, are optimized for endurance and sustained activities due to their high aerobic capacity and slow contraction rate. They are essential for activities like marathon running and for maintaining posture.