Which fibre type makes up most of an elite marathon runner's leg muscles, and why?

An elite marathon runner has a high proportion of type I fibres. Type I fibres can keep contracting for hours without fatiguing.

What are the characteristics of type IIx fibres?

Type IIx fibres contract very quickly and produce the greatest force of any fibre type. Type IIx fibres fatigue very quickly.

Why do type IIx fibres fatigue so quickly?

Type IIx fibres release energy anaerobically, producing lactic acid. Type IIx fibres also have few mitochondria and a poor capillary supply.

Edexcel GCSE Physical Education 1PE0

Applied Anatomy and Physiology

Topic overview Functions and classification of bones Bones of the skeleton and the vertebral column Joints and the movements they allow Ligaments, tendons and muscle types Voluntary muscles and antagonistic pairs Fast and slow twitch muscle fibres The heart, circulation and blood Blood vessels and vascular shunting Breathing, lung volumes and gas exchange Aerobic and anaerobic energy release Short-term effects of exercise

Movement Analysis

Topic overview First, second and third class levers Mechanical advantage and disadvantage Planes and axes of movement

Physical Training

Topic overview Health, fitness, exercise and performance Components of fitness The purpose and value of fitness testing Fitness tests and normative data Principles of training Training methods and fitness classes Long-term effects of training PARQ, sports injuries and RICE Performance-enhancing drugs Warm up and cool down

Use of Data

Topic overview Collecting and presenting data Interpreting data and normative comparisons

Health, Fitness and Wellbeing

Topic overview Physical, emotional and social health and wellbeing Personal exercise programmes and lifestyle choices A sedentary lifestyle and its consequences A balanced diet and the macronutrients Micronutrients, water, fibre and hydration Optimum weight and energy balance

Sport Psychology

Topic overview Classification of skills Practice structures Goal setting and SMART targets Types of guidance Types of feedback Mental preparation for performance

Socio-Cultural Influences

Topic overview Participation rates and personal factors Commercialisation and the media Advantages and disadvantages of commercialisation Sportsmanship, gamesmanship and deviance

Applied Anatomy and Physiology

Fast and slow twitch muscle fibres

3 things to know
Component 1

Overview

Type I, type IIa and type IIx muscle fibres, their characteristics, and which events and positions each fibre type suits.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Name the three types of muscle fibre.

Key term

What are the characteristics of type I fibres?

Key term

Why are type I fibres suited to aerobic work?

Questions from this subtopic

Each one with the model answer underneath.

1
Name the three types of muscle fibre.
Model answer
The three types are type I, type IIa and type IIx. Type I fibres are slow twitch, and type IIa and type IIx are fast twitch.
2
What are the characteristics of type I fibres?
Model answer
Type I fibres contract slowly and with little force. Type I fibres are highly resistant to fatigue, so they can work for a long time.
3
Why are type I fibres suited to aerobic work?
Model answer
Type I fibres have many mitochondria and a dense network of capillaries. Type I fibres also store oxygen in myoglobin, so they are well supplied with oxygen.
4
Which fibre type makes up most of an elite marathon runner's leg muscles, and why?
Model answer
An elite marathon runner has a high proportion of type I fibres. Type I fibres can keep contracting for hours without fatiguing.
5
What are the characteristics of type IIx fibres?
Model answer
Type IIx fibres contract very quickly and produce the greatest force of any fibre type. Type IIx fibres fatigue very quickly.
6
Why do type IIx fibres fatigue so quickly?
Model answer
Type IIx fibres release energy anaerobically, producing lactic acid. Type IIx fibres also have few mitochondria and a poor capillary supply.

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Applied Anatomy and Physiology

Movement Analysis

Physical Training

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Most veins carry blood.

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