Our 3 Types of Muscle Fibers: Our muscles are made up of three different types of muscle fibers: - Type 1- Type 2a- Type 2bEach of these fibers have different physiological properties, energy systems, and physical traits.- Type 1 fibers are more aerobic, contribute to longer duration activity, are smaller in size, and are slow twitch. - Type 2a fibers are transitional and vary between type 1 and type 2b fiber properties. These fibers will adapt and change their composition, depending on the type