HB101 Lecture Notes - Lecture 8: Vo2 Max, Cardiorespiratory Fitness, Overtraining
HPE110: Muscle structure and function
• Muscle structure and contraction
• Muscle fibre types (and properties)
• Purpose of training
• Training principles
Muscle structure
Contractile proteins
• Myosin
• Thick filaments with globular heads
• Actin
• Thin filaments
• Actin
• Tropomyosin
• Troponin
Mechanisms of muscle contraction
• Myosi head ids to a atie site o ati ross ridge
• Myosin head moves pulling actin filaments towards the centre of the sarcomere
poer stroke
• Sacromere shortens, muscle shortens, force is generated
• Cross bridges detach
• Dependent upon sufficient Ca2+ and ATP
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Sliding Filament Theory
The role of Ca2+
• At rest, myosin and actin are unable to bind d/t tropomyosin and troponin
• Tropomyosin covers the binding sites on actin
• Troponin holds tropomyosin in place
• Ca2+ binds to troponin moves tropomyosin away to expose myosin
binding site on actin
The role of ATP
• Myosin head contains a binding site for ATP
• ATP ADP + P = cross bridge + power stroke
• A new ATP binds to myosin to release it from actin
Excitation-contraction coupling
Sequence of events that begin with a neural impulse and end with contraction
• Excitation of a motor nerve
• Propagation of an action potential
• Events at the neuromuscular junction
• Calcium release from sarcoplasmic reticulum
• Sliding Filament Theory
• Muscle contraction
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Muscle fibre types
• Type I fibres (slow twich)
• Type II fibres (fast twitch)
• Type IIa
• Type IIb
• Differences in speed of contraction, maximum force production,
oxidative capacity, fatigaility…
Type I muscle fibres
• Relatively small in diameter
• Slow contractile speed
• Low force production
• High oxidative (aerobic) capacity
• Many mitochondria
• Many capillaries
• Lots of myoglobin
• Lots of aerobic enzymes
• Highly resistant to fatigue
Recruited during prolonged aerobic exercise
Aerobic capacity and %ST fibres
Type II muscle fibres
• Relatively large in diameter
• Fast contractile speed
• High force production
• High glycolytic capacity
• Lots of glycolytic enzymes
• Greater glycogen and PCr stores
• Highly fatigable
Recruited during high-intensity exercise
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find more resources at oneclass.com
Document Summary
Hpe110: muscle structure and function: muscle structure and contraction, muscle fibre types (and properties, purpose of training, training principles. Contractile proteins: myosin, thick filaments with globular heads, actin, thin filaments, actin, tropomyosin, troponin. The role of atp: myosin head contains a binding site for atp, atp adp + p = cross bridge + power stroke, a new atp binds to myosin to release it from actin. Sequence of events that begin with a neural impulse and end with contraction: excitation of a motor nerve, propagation of an action potential, events at the neuromuscular junction, calcium release from sarcoplasmic reticulum, sliding filament theory, muscle contraction. Muscle fibre types: type i fibres (slow twich, type ii fibres (fast twitch, type iia, type iib, differences in speed of contraction, maximum force production, oxidative capacity, fatiga(cid:271)ility . Type i muscle fibres: relatively small in diameter, slow contractile speed. Low force production: high oxidative (aerobic) capacity, many mitochondria, many capillaries.
