The Neuromuscular System

Fibre types

• Slow (Type 1) - Slower contraction speed, low intensity, long distance, energy produced aerobically, use oxygen efficiency, low in force produced, Used for a 5K run.

• Fast (Type 2) - Resistant to fatigue (not as much as slow twitch), longer burst, higher intensity. Used for a 400m run.

• Fast (Type 2x) - Used for explosive events where a quick burst of energy is required. The most powerful. Used in a 100m sprint.

Definitions

• Capillary density - These are the blood vessels where gaseous exchange takes place - they allow oxygen to enter the muscles.

• Mitochondria - These are the powerhouses of the muscle where the energy is produced aerobically.

• PC - This stands for phosphocreatine, which is the fuel used to provide more energy for highly expensive activities.

• Largest motor neurone - This is part of the motor unit, which is responsible for passing the impulse which fires up the muscle fibres to contract.

• Triglycerides - Fat is stored as these, they are broken down to produce energy, but this process can only take place under aerobic conditions.

All or none law

• Only all of the muscle fibres can contract in a motor unit. You cant have 50% of the muscle fibres contracting and the other 50% not contracting. They’re only ever all contracting or not contracting at all.