1.1 Muscle types, fibers and recovery rates Flashcards
What is skeletal muscle?
muscles attached to the skeleten which can o ly contract when stimulated by an electrical impulse sent from the central nervous system
What are motor neurones?
specialised cells which transmit never impulses rapidly to a group of muscle fibres.
What is the motor unit?
a motor neuron and the muscle fibres stimulated by its axon
What is an action potential?
positive electrical charge inside the nerve and muscle cells which conducts the nerve impulse down the neuron and into the muscle fibre
What is the place where the axons motor end plates meet the muscle fibre
neuromuscular junction
What is the synaptic cleft?
a small gap between the motor end plates and muscle fibre
An action potential cannot cross the synaptic cleft without a ?
neurotransmitter called acetylcholine
Where is the neurotransmitter located and why?
secreted in synaptic cleft to help nerve impulses across the gap
What does an action across the synaptic cleft cause?
wave of contraction down the muscle fibre (muscle contraction)
What is the all or none law?
when an action potential that reaches a threshold charge, all muscle fibres within the motor unit will contract at the same time and with maximum force. If the action potential does not reach the threshold charge, none of the muscle fibres will contract
Give the flow diagram of the role of a motor unit?
- nerve impulse initiated in the motor neuron cell
- nerve impulse conducted down the axon of the motor neuron by a nerve action potential to the synaptic cleft
- neurotransmitter called acetylcholine is secreted into the synaptic cleft to conduct the nerve impulse across the gap
- If the electrical charge is above a threshold, muscle fibre will contract
- happens in an all or non fashion
What is the strength of contraction dependent on?
the number of motor units recruited by the brain
The greater the number of motor units recruited the greater … ?
the force of contraction
What are the three types of muscle fibres?
- slow oxidative (SO)
- fast oxidative glycolytic (FOG)
- Fast glycolytic (FG)
What are slow oxidative muscle fibres?
a type of muscle fibres rich in mitochondria, myoglobin and capillaries which produces a small amount of force over a long period of time
What are fast glycolytic muscle fibres?
type of muscle rich phosphocreatine which produces a maximal force over a short period of time
What are fast glycolytic muscle fibres?
structurally designed to work anaerobically, with large stores of phosphocreatine for rapid energy production and the largest amount of force. (fatigue quickly)
What is phosphocreatine?
high energy compund stored in the muscle cell used as a fuel for very high intensity energy production
WHat are mitochondria?
structure in the sarcoplasm responsible for aerobic energy production
What is myoglobin?
a protein in the muscle responcible for transporting oxygen to the mitochondria
What does aerobic work mean?
low, intensity long duration exercise in the presence of oxygen
What does anaerobic work mean?
high intenisity, short duration excersise without oxygen
Which sports have a high percentage of slow oxidative fibres?
endurance athletes: marathon, triathlon, cross-country skiing
Which sports have a high percentage of fast oxidative glycolytic fibres?
high intensity athletes:
800m-1500m run
200m freestyle swim
Which sports have a high percentage of fast glycolytic muscle fibres?
explosive athletes:
60-100m sprinting
Javelin
long jump
What are the 5 structural characteristics of slow oxidative fibres?
Size: small Fibres per neuron: few Mitochondria density: hight Capillary density: high Myoglobin content: high
What are the 5 structural characteristics of fast oxidative glycolytic fibres?
Size: large Fibres per neuron: Many Mitochondria density: moderate Capillary density: high Myoglobin content: Moderate
What are the 5 structural characteristics of fast glycolytic fibres?
Size: large Fibres per neuron: Many Mitochondria density: low Capillary density: low Myoglobin content: low
What are the 5 functional characteristics of slow oxidative fibres?
Speed: slow Force of contraction: low Fatigue resistance: High Aerobic capacity: High Anaerobic Capacity: Low
What are the 5 functional characteristics of fast oxidative glycolytic fibres?
Speed: Fast Force of contraction: high Fatigue resistance: moderate Aerobic capacity: moderate Anaerobic Capacity: moderate
What are the 5 functional characteristics of fast glycolytic fibres?
Speed: fast Force of contraction: high Fatigue resistance: low Aerobic capacity: low Anaerobic Capacity: high
Explain how to maximise aerobic training to maximise slow oxidative fibres?
1:1 or 1:05 work to rest ratio. -running
How are fast glycolytic fibres recruited?
near muscular failure
Explain how to maximise fast glycolytic fibres when working?
1:3 work to rest ratio
3-5 mins rest with just 2-6 reps
Explain the recovery for weight training (optimising fast glycolytic fibres)
take 4-10 days to recover. leave a minimum of 48 hours before re-working the muscle
