Muscle Fibre Types Flashcards
What is the strength of a muscle contraction dependant 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 3 types of muscle fibre?
Slow oxidative (SO, type 1)
Fast oxidative glycolytic (FOG, type 2a)
Fast glycolytic (FG, type 2b)
Definition of slow oxidative muscle fibre
A type of muscle fibre rich in mitochondria, myoglobin, and capillaries which produces a small amount of fore over a long period of time
Definition of fast glycolytic muscle fibres
A type of muscle fibre rich in phosphocreatine which produces a maximal amount of force over a short period of time
What are the structural characteristics of slow oxidative muscle fibres?
Small neuron size
Few fibres per neuron
High capillary density
High mitochondria density
High myoglobin content
Low PC stores
What are the functional characteristics of slow oxidative muscle fibres?
Slow speed of contraction
Low force of contraction
High fatigue resistance
High aerobic capacity
Low anaerobic capacity
What is a sporting example of slow oxidative muscle fibres?
Marathon, triathlon, cross-country skiing
What are the structural characteristics of fast oxidative glycolytic muscle fibres?
Large neuron size
Many fibres per neuron
High capillary density
Moderate mitochondria density
Moderate myoglobin content
High PC stores
What are the functional characteristics of fast oxidative glycolytic muscle fibres?
Fast speed of contraction
High force of contraction
Moderate fatigue resistance
Moderate aerobic capacity
Moderate anaerobic capacity
What is a sporting example of fast oxidative glycolytic muscle fibres?
800m - 1500m running
200m freestyle swimming
What are the structural characteristics of fast glycolytic muscle fibres?
Large neurone size
Many fibres per neuron High capillary
Low capillary density
Low mitochondria density
Low myoglobin content
High PC store
What are the functional characteristics of fast glycolytic muscle fibres?
Fast speed of contraction
High force of contraction
Low fatigue resistance
Low aerobic capacity
High anaerobic capacity
What is a sporting example of fast glycolytic muscle fibres?
60-100m sprint, javelin, long jump
What is myoglobin?
A protein in the muscle responsible for transporting oxygen to the mitochondria
What is the purpose of SO muscle fibres?
Work aerobically producing a small amount of force resisting fatigue for a long period of time
What is the purpose of fast glycolytic muscle fibres?
Work anaerobically with large stores of phosphocreatine producing large amount of force but fatiguing quickly. High intensity, short duration
What is the relationship between muscle fibre type, force production and time
-Small motor neurones stimulate relatively few small muscle fibres. Creating a motor unit which produces small and slow amount of force over a long period of tine, resting fatigue well. eg. maintaining posture
-Large motor neurones stimulate many large muscle fibres, Creating a motor unit which produces large amounts of force rapidly but fatigues quickly
What type of exercise are SO muscle fibres recruited for?
sub-maximal aerobic work
What is the recovery rate for SO muscle fibres?
-Quick recovery, avaliable after 90 seconds
-Aerobic training with low work:relief ratio, 1:1 or 1:0.5
-Training can be performed safely on a daily basis
-Low intensity use of SO muscle fibres advised between heavy weight training session to increase blood flow, enhance the healing process
What is the recovery rate for FOG/FG muscle fibres?
-Only recruited in last 2-20 seconds of a contraction, near muscle exhaustion or when maximal effort required quickly
-Once FG fibres used to exhaustion, take 4-10 days to recover. Maximal weight training sessions should leave at least 48 hours before using same muscle group again
-Very high work:relief ratios for maximal weight training to maximise use of FG muscle fibres. 1:3+ ratio
What is the graph to show motor unit recruitment released to intensity of exercise?
