Download 11/21 muscle fiber types answers

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PERIOD:_______
S3.H9.L2- Identifies the structure of a skeletal muscle and fiber types as they relate to muscle development
Muscle Fiber Types
Within skeletal muscle there are three types of fiber. Type 1= Slow twitch muscle fiber, type 2A= fast
twitch muscle fiber and type 2B= fast twitch muscle. Each fiber type has different qualities in the way
they perform and how quickly they fatigue.
Type I
Type I fibers are also known as slow twitch fibers. Slow- twitch (Type I) fibers are identified by a slow
contraction time and a high resistance to fatigue. They are red in color due to the presence of large volumes of
myoglobin (hemoglobin of muscle- oxygen carrying pigment=red & conveys oxygen to the muscle), oxygen and
high numbers of Mitochondria (energy production). They are capable of producing repeated low-level
contractions by producing large amounts of ATP (adenosine triphosphate) through an aerobic metabolic cycle.
Functionally, ST fibers are used for aerobic activities requiring low-level force production, such as walking and
maintaining posture. Most activities of daily living use ST fibers. Athletes with a high number of ST muscle
fibers would include distance runners, swimmers, cyclists, etc.
Type 2A
Type 2A fibers are also sometimes known as fast oxidative fibers and are a hybrid of type I and 2 fibers. These
fibers are also red in color due to the fact they contain a large number of mitochondria and myoglobin. They
manufacture and split ATP at a fast rate by utilizing both aerobic and anaerobic metabolism and so produce
fast, strong muscle contractions, although they are more prone to fatigue than type I fibers. Resistance
training can turn type 2B fibers into type 2A due to an increase in the ability to utilize the oxidative cycle.
Functionally, they are used for prolonged anaerobic activities with a relatively high force output, such as racing
400 meters.
Type 2B
Often known as fast glycolytic fibers Type 2B muscle fibers are white in color due to the fact they have a low
level of myoglobin and few mitochondria. They produce ATP at a slow rate by anaerobic metabolism and
break it down very quickly. Therefore, they are very sensitive to fatigue and are used for short anaerobic, high
force production activities, such as sprinting, hurdling, jumping, and shot put. These fibers are also capable of
producing more power than ST fibers
Fiber Type
Color
Contraction Time
Resistance to Fatigue
Activity used for
Metabolic cycle used
Force Production
Sport/athletic
example
Characteristics of Three Muscles Fiber Types
Type 1- Slow Twitch Type 2A- Fast Twitch
Red
Red
Slow
Fast
High
Medium/Intermediate
Aerobic
Long Term Anaerobic
Aerobic
Aerobic & Anaerobic
Low
High
Distance Runner
400-800 M sprinter
Type 2B- Fast Twitch
White
Very Fast
Low
Short Term Anaerobic
Anaerobic
Very High
100 Sprinter/Hurdler
Determining Muscle Fiber Type
The only way to directly determine the fiber-type composition in an athlete is to perform an invasive muscle biopsy test
(in which a needle is stuck into the muscle and a few fibers are plucked out to be examined under a microscope),
Indirect methods include 1 Rep Max and many reps at 80% of the athletes 1 Rep Max or for younger athletes or people
new to sports, try different events. Their dominant fiber type will soon become evident based on their success in certain
events
https://www.youtube.com/watch?v=3L9JUfzh66I
https://www.youtube.com/watch?v=Uxwh2IIg_Z0 – sprinter vs. marathoner
http://www.coachr.org/fiber.htm
www.teachpe.com
Muscle Fiber Types QUIZ
Circle how many questions out of 5 that you answered correct?
1
2
Write the correct answers for each of the questions below:
1.____Slow Twitch______
2___Mitochondira & Myoglobin____
3.___Fast Glycolitic__ (the quiz online says the right answer is slow anabolic but that is INCORRECT)
4.____2B & 2A_________________________
5. _____Type 1____________________
3
4
5