Definition of terms• Aerobic Exercise: is physical exercise that intends to improve the oxygen system.• Aerobic means "with oxygen", and refers to the use of oxygen in the bodys metabolic or energy-generating process. Many types of exercise are aerobic, and by definition are performed at moderate levels of intensity for extended periods of time.
Muscle• an organ that, by cellular contraction, produces the movements of life
Muscle fibre• any of the cells of skeletal or cardiac muscle tissue which is an elongated contractile cell that forms the muscles of the body• are mainly composed of the proteins, actin and myosin.
A.T.Pase• Enzymes that cause the conversion of A.D.P to release energy
Mitochondria• are known as the powerhouses of the cell. They are organelles that act like a digestive system that takes in nutrients, breaks them down, and creates energy for the cell.
Myoglobin• is a protein and has oxygen bound to it, thus providing an extra reserve of oxygen so that the muscle can maintain a high level of activity for a longer period of time.
Slow Twitch• Muscle fibers that produce energy by converting fats into energy aerobically.
Fast Twitch• Muscle fibers that produce energy by breaking down glycogen in the absence of oxygen. They produce rapid contractions, but create lactic acid as a by-product.
Types of Muscle Fibrethere are two main type of muscle fibre:• Type I – often called slow-twitch or slow fibre or highly-oxidative muscle fibres• Type II – often called fast-twitch or Fast fibers or low-oxidative muscle fibres
Slow Twitch Muscle Fibre• contain more mitochondria• smaller in size• have better blood supply• contract more slowly
more fatigue resistant than their fast-twitch brothers. produce energy, primarily,through aerobic metabolism offats and carbohydrates.
Type 1 Muscle Fibreare only aerobic and contain an abundance of mitochondria (where the Krebs cycle occurs).The major source of energy for Type I is fat through the Krebs cycle.
They also contain large amounts ofmyoglobin: a pigment similar tohaemoglobin that also storesoxygen – that provides anadditional store of oxygen forwhen oxygen supply is limited
Type II has three subgroups:Fast Oxidative GlycolyticFast GlycolyticIndeterminate
Fast Oxidative Glycolytic -Aerobicburns glucosemitochondria present but not as many as type I
Fast Glycolytic• Anaerobic• burns glucose• no mitochondria
produces lots of lactic acid whichcan enter mitochondria of type Ior IIa heart muscle can utilize all thelactic acid it can get. Any lacticacid left over enters the liver andis reconstitued into glucose.
Indeterminateundifferentiated fibers -can become type IIa or IIb
The effect of aerobic exercise on muscle fibreIncrease blood capillaries to muscle fibreIncrease in number and size of mitrochrondriaIncrease enzymic action (A.T.Pase)
Exercise suitable for slow twitch muscle fibre• Marathon• Cross country cycling• Swimming• Skating• Skiing• Triathlon, Decathlon, Heptathlon• Running