Physiology 5 Muscle performance
Objectives:
- be familiar with the limitations to muscle performance
- fibre types,
- length tension relationships
- Understand the role of the motor unit
- motor neuron and the muscle fibres it innervates
- understand how the force of muscle contraction is controlled
- recruitment
- Frequency/rate modulation
Objective based questioning:
Content:
Types of muscle fibres
Type I slow form of myosin ATPase many mitochondria high levels fof exadative enzymes, rich blood suppluy slow serca pump, less rapid contraction
primarily uses fats
Type IIB glycolytic fast form of myosin ATPase few mitochondria. low levels of oxidative enzymes, fewer capillaries fast form of serca mainly used
Type IIA
fast form of myosin atpase
mixed everything else
limits to performance
velocity-load relationship you can be really quick with light load
length-tension relationship
Active tension: when very contracted not much force can be generated when very lengthened not much force can be generated in the middle is the best
passive tension is elasticity from the muscle
Muscle spindles give feedback to modulate force
Motor units
A motor unit is a neuron and all of the muscle fibres it innervates all muscle fibres in a motor unit are the same type
the number of muscle fibres in a muscle unit can vary so the body can swap between power and precision
hwo to modulate force generted with muscle units frequency modulation, as more pulses to a single unit means more force, and recruitment, more motor units recruited means more tension
usually smaller more fatigue resistant motor units are recruited first followed by bigger ones as you put more force into an action