<P> Skeletal muscle is further divided into several subtypes: </P> <Ul> <Li> Type I, slow oxidative, slow twitch, or "red" muscle is dense with capillaries and is rich in mitochondria and myoglobin, giving the muscle tissue its characteristic red color . It can carry more oxygen and sustain aerobic activity . <Ul> <Li> Type I muscle fiber are sometimes broken down into Type I and Type Ic categories, as a result of recent research . </Li> </Ul> </Li> <Li> Type II, fast twitch muscle, has three major kinds that are, in order of increasing contractile speed: <Ul> <Li> Type IIa, which, like slow muscle, is aerobic, rich in mitochondria and capillaries and appears red when deoxygenated . </Li> <Li> Type IIx (also known as type IId), which is less dense in mitochondria and myoglobin . This is the fastest muscle type in humans . It can contract more quickly and with a greater amount of force than oxidative muscle, but can sustain only short, anaerobic bursts of activity before muscle contraction becomes painful (often incorrectly attributed to a build - up of lactic acid). N.B. in some books and articles this muscle in humans was, confusingly, called type IIB . </Li> <Li> Type IIb, which is anaerobic, glycolytic, "white" muscle that is even less dense in mitochondria and myoglobin . In small animals like rodents this is the major fast muscle type, explaining the pale color of their flesh . </Li> </Ul> </Li> </Ul> <Li> Type I, slow oxidative, slow twitch, or "red" muscle is dense with capillaries and is rich in mitochondria and myoglobin, giving the muscle tissue its characteristic red color . It can carry more oxygen and sustain aerobic activity . <Ul> <Li> Type I muscle fiber are sometimes broken down into Type I and Type Ic categories, as a result of recent research . </Li> </Ul> </Li> <Ul> <Li> Type I muscle fiber are sometimes broken down into Type I and Type Ic categories, as a result of recent research . </Li> </Ul>

What is the difference between muscle and tissue