Muscle Fibre Types. There are two kinds of muscle fibres Slow-twitch: red/dark in colour Generate...
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Transcript of Muscle Fibre Types. There are two kinds of muscle fibres Slow-twitch: red/dark in colour Generate...
Muscle Fibre TypesMuscle Fibre Types
There are two kinds of muscle fibres
Slow-twitch: red/dark in colour Generate tension slowly Relax slowly Able to maintain a lower level of tension for a
long duration Useful during activities such as long-distance
swimming, cycling and running
Slow-twitch cont...Slow-twitch cont... Have low levels of an enzyme called myosin
ATPase – used to provide instant energy for muscle contraction
Also have low levels of glycotic enzymes which allow the release of glycogen within muscles
What is an enzyme? An enzyme is a protein that acts as a catalyst
for chemical reactions The enzyme itself is not affected by the
chemical reaction
Fast-Twitch Muscle FibresFast-Twitch Muscle Fibres
More pale in colour Tense and relax quickly Can generate large amounts of tension for short
periods of time High level of myosin ATPase and glycolytic
enzymes Activate 2-3x faster than slow-twitch fibres Short sprints, powerlifting, explosive jumping
The Importance of Myoglobin The differences between muscle fibre types =
the extent to which the muscle relies on oxygen in the production of energy
Myoglobin is a protein that delievers oxygen to working muscles
This allows energy-producing biochemical reactions to be sustained over a long period of time
Using aerobic processes for energy production = ability to sustain activity longer
Three Fibre Types 1 type for slow-twitch 2 types for fast-twitch Type I or Slow-Oxidative (SO): these muscles
generate energy slowly More fatigue-resistant Depend on aerobic processes
Type IIA Type IIA or Fast-Oxidative Glycolytic (FOG)
Intermediate High-speed energy release Glycolytic capacity
Type IIB Type IIB or Fast-Glycolytic (FG)
Store a lot of glycogen and high levels of enzymes necessary for quick contraction
Does not require oxygen
The Distribution of Muscle Fibre Types
A muscle's fibre makeup determines its function and at the same time what a muscle does gives us an indication of what it is made of
Use the terms tonic muscles and phasic muscles as a way to describe basic functions
Tonic Muscles
Assist the body with maintaining posture or stability during walking, standing, throwing, etc
High % of type I fibres (slow-twitch) i.e. Soleus – performs dorsiflexion and is key in
maintaining body posture
Phasic Muscles Higher % of type IIA and IIB fibres i.e. The biceps – key muscle for lifting and
power in the arm Lower % of type I
How Do I Find Out My Muscle Type?
The only way to find out what percentage of muscle fibre types are found in your muscles is to have a biopsy performed :( Must acquire a tissue
sample Take out a small
portion of the muscle and placing it under a microscope
Fibre Type and Athletic Performance
Read this section on page 93 of your textbook Answer the following questions: Give an example of a sport that requires fast-
twitch muscles fibres and an example of a sport that requires slow-twitch
How would an elite athlete maximize their performance?
What is the goal of the workout of an Olympic shotputter and a hockey player (think of the energy system they use)
Questions cont...
Endurance athletes train their muscles to? The goal of an endurance workout is to? What is the outcome of endurance workouts?