Type I and Type II Muscle Fibers

• Physiological factors determining the components of physical fitness include endurance, strength, speed, and flexibility.

Type I fibers/Slow Twitch Fibers

• Also known as slow oxidative fibers.
• Contain more capillaries, myoglobin, and mitochondrial enzymes than rapid twitch fibers.
• Improve aerobic activity and fatigue tolerance.
• Fibers turn red with a bigger blood flow due to more capillaries.
• Contract slowly and stay constricted for longer periods.
• Release considerable energy without tiring.
• Beneficial in long-distance sports like cycling, swimming, and running.

Type II fibers/Fast Twitch Fibers

• Known as rapid twitch or fast glycolytic fibers.
• Have a low aerobic capacity and fatigue tolerance.
• Have fewer mitochondria, despite a high concentration of glycolytic enzymes that promote anaerobic activity.
• Produce energy without a blood supply.
• Lighter in color than slow twitch fibers.
• Generate a little amount of energy quickly.
• Contract and tear quickly and use a lot of energy.
• Used for anaerobic exercises like sprinting, throwing, and jumping.

Endurance

• Aerobic capacity.
• Lactic acid tolerance.
• Movement economy.
• Muscle composition.

Strength

• Size of muscles.
• Body weight.
• Muscle composition.
• Intensity of nervous impulse.

Speed

• Mobility of the nervous system.
• Muscle composition.
• Explosive strength.
• Flexibility.

Flexibility

• Muscle strength.
• Age and gender.
• Stretchability of muscle.
• Internal environment.
• Previous injury.

Effects of Exercises on Cardiorespiratory System

• Increases the size of the heart.
• Decreases resting heart rate.
• Increases blood flow.
• Decreases blood pressure.
• Increases blood volume.
• Decreases the rate of respiration.
• Increases endurance.
• Increases lungs efficiency.

Effects of Exercises on the Muscular System

• Changes the shape and size of muscles.
• Formation of more capillaries.
• Controls extra fat.
• Increases food storage.
• Provides health benefits.
• Non-functioning fibers become active.
• Improves efficiency and movement of muscles.
• Body posture remains correct.

Physiological Changes Due to Aging

• Aging includes progressive degeneration of organ systems and tissues.
• Largely determined by genetics and influenced by environmental factors like diet, exercise, exposure to micro-organisms and pollutants.
• Muscular Strength: The maximal force that a muscle or muscle group can generate.
• Neural Function: Nearly a 40% decline in the number of spinal cord axons and a 10% decline in nerve conduction velocity reflect cumulative effects of aging on central nervous system functioning.
• Pulmonary Function: Mechanical constraints on the pulmonary system progress causing deterioration.
• Cardiovascular Function: Cardiovascular function and aerobic capacity are also affected.

Sports Injuries

• Caused during sports activities or by recent trauma to a certain body location.
• Injury results from incorrect movement, hitting/colliding with equipment, violent sporting maneuvers, overtraining, or a lack of conditioning.

Overview of Type I (slow twitch) and Type II (fast twitch) muscle fibers. Type I fibers are beneficial in endurance sports. Type II fibers have a low aerobic capacity and fatigue tolerance.