B4 + B5 - Muscle fibres
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What are the three types of muscle fibre?
• type 1 • type IIa • type IIx
What are the characteristics of type 1?
• aerobic respiration • slow twitch • low power output • very slow to fatigue • high number of mitochondria • suited to marathon running
What are the characteristics of type 2a?
• fast twitch • good power output • fatigues quickly • low number of mitochondria • anaerobic respiration • suited to 200-400 meters
What are the characteristics of type 2x?
• extremely fast twitch • very high power output • fatigues very quickly • low number of mitochondria • anaerobic respiration • suited to 100 meters
What are mitochondria?
• this is the site within muscle cells where respiration occurs (either aerobic or anaerobic) • more mitochondria = better ability to utilise oxygen when exercising • energy is created using glucose within these mitochondria
Can you change the mix of type 1, 2a and 2x fibre types in your muscles?
• no, each person is different (even brothers and sisters) • within each person, the different muscle groups also have different concentrations of each type (e.g. legs may have high 1, arms may have higher 2a) • the percentage of fibre types you have is set and it is based on your genetics and the number/ concentration of each muscle fibre type cannot be altered • BUT through effective training the effectivity of each muscle type can be drastically improved
Two real life examples in sports performers of fibre types effecting their performance.
Usain Blot - genetics have given him a very high concentration of 11x compared to other people Mo Farah - genetics and training have meant his type 1 fibres are exceptionally efficient
What is a isometric muscle contraction?
• the length of a muscle does not change and the joint angle does not alter • the muscle is actively engaged in holding a static position
Examples of isometric muscle contraction?
• abdominal plank position • wall sit (quadriceps) • this type of muscle work is easy to undertake but rapidly leads to fatigue = it can cause sharp increases in blood pressure as blood flow is reduced
What is a concentric muscle contraction?
• tension rises to meet resistance, remains stable as muscle shortens
Examples of concentric muscle contraction.
• upwards phase of a bicep curl (bicep brachii)
What is a eccentric muscle contraction?
• contraction when muscle returns to it’s normal length after shortening against resistance (under strain) • contracting and lengthening (thinner)
Examples of eccentric muscle contraction.
• bicep curl in the controlled downwards phase (bicep brachii)
What is the aim of putting strain/ pressure on the muscles (simply)?
muscle micro-tares = DOMS = muscle growth