exercise science

For this science class we will review the three major types of muscle fibres.

The major muscle fiber groups are

Type 1

This is predominately the muscle fibre that is used when you perform endurance type of activities such as running or weight sessions where you are lifting in the 25 plus rep range. Generally if you are ever lifting in this fashion you are not looking to gain strength but rather hoping to improve the muscle fibre's ability to deal with lactic acid build-up. This type of training should only be utilized by endurance athletes such as marathon runners or cyclists however as it is not really that beneficial for other athletes.

Type 2a

These are much more focused on generating strength than the type 1 and have a rapid contraction rate. When you are performing typical strength training exercises in the 6-8 rep range this is predominately the muscle fibre type you are going to call upon. They have a high capability of generating ATP (high energy compound), which is the prime source of fuel for short duration activities.

Type 2b

These types of muscle fibres generate the most force and are used predominately in activities that require an all out burst of effort. They rely exclusively on ATP for fuel and are very large in nature. They have a small number of mitochondria and fatigue very rapidly.

These types of muscle fibres are going to be seen in highest proportions in athletes such as sprinters or power lifters. Since these athletes are rarely performing activities that last much longer than 60 seconds in length they simply do not need to develop their slow twitch muscle fibres.

Questions:

1. What is meant by the terms muscle endurance and muscle strength?

2. What is meant by the terms absolute and relative strength?

3. How does skeletal muscle differ from smooth muscle and cardiac muscle?

4. Muscles can contract while extending a joint or flexing a joint. What is the name for these types of movements?

5. There are two types of isotonic contractions – eccentric and concentric. What

movement action is described by each of these terms?

6. What is the difference between an isotonic and an isometric contraction?