Week 2 Muscular System Flashcards
Define Type I muscle fibres
Slow twitch fibres, associated with the aerobic energy system. Fatigue resistant.
Define type IIa muscle fibres
Fast twitch fibres, associated with the anaerobic glycolysis energy system. Fire quicker than type I but create lactic acid, fatigue resistant
Define type IIx muscle fibres
Fast twitch fibres associated with ATP-PCr energy system. Fastest speed fibres, fatigue/run out quickly
What is the spatial recruitment: size principle
Size principle states that the order of recruiment is directly related to their motor neuron size, slow twitch fibres which have smaller motor neurons are recruited before fast twitch fibres
What is the principle of orderly recruitment
States that motor units are activated in a fixed order, based on their ranking in the muscle
What is the force-power relationship
At any given velocity of a movement the power generated is greater in muscle with a higher percent of fast twitch fibres
What is a motor unit
A motor unit is made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron’s axonal terminals.
What is the role of genetics regarding muscle fibre types
Genetics determines the type of motor neuron innervating individual muscle types, muscle fibres become specialized according to the type of motor neuron that stimulates them
What is the optimal length of a muscle for maximal force?
2.25 micrometres
What is the relationship between force and speed of a muscle?
The higher the speed means the higher the force
What is the relationship between power and speed of a muscle?
The higher the speed means the higher the power until you overdo the speed then it declines
What are factors influencing force production (6)
# of motor units activated Type of motor units activated Muscle size Initial muscle length Joint angle Speed of muscle action
What do the receptors in muscles do
Provide sensory feedback to nervous system
- Tension development by muscle - Account of muscle length
Define Strength
Maximal force a muscle or muscle group can generate
Define power
Production of strength and speed of a movement
Define muscular endurance
Capacity to sustain repeated muscle actions
Define fibre hypertrophy and fibre hyperplasia (muscle hypertrophy)
Hypertrophy is an increase in size of muscle fibres
Hyperplasia is an increase in number of muscle fibres
Define difference between transient and chronic muscle hypertrophy
Transient is pumping of muscles during exercise due to fluid accumulation from the blood plasma
Chronic increase in muscle size after long term training
Define how muscles actually become larger (fibre hypertrophy)
Number of myofibrils and actin and myosin filaments increase
What are the two main processes that explain muscle soreness? (DOMs)
Microscopic tears in muscle fibres/connective tissue
Odema - accumulation of fluid inside muscle compartment
List Armstrongs sequence of events (6)
- Disruption of sacromeres
- Membrane damage
- Ca2+ leaks from SR
- Protease activation
- Inflammatory response
- Edema and pain
What is the repeated bout effect?
A bout of unfamilar exercises resulting in delayed onset muscle soreness. Following recovery, another bout of same exercise results in minimal injury
What are the three theories for the repeated bout effect
Neural theory - recruitment of larger number of muscle fibres
Connective tissue theory - Increased connective tissue to protect muscle
Cellular theory - synthesis of protective proteins with muscle fibres
Name the 4 neural adaptations of muscle strength
Synchronization and recruitment of additional motor units
Autogenic inhibition - sudden relaxation of muscle upon development of high tension
Coactivation of agonist and antagonist muscles
Rate coding - the firing frequency of motor units
Define how early and long term gains of strength differ
Early gains in strength appear to be influenced more by neural factors
Long term strength increases are largely the result of muscle fibre hypertrophy
How do delayed onset muscle soreness affect performance (5)
Decrease in force generating capacity in muscles Physical disruption Failure in E-C coupling process loss of contractile protein Muscle glycogen synthesis impaired
