The main source of human strength is muscle contraction, and most basic activities of the human body are inseparable from muscle participation, such as leg lifting, walking, bending and so on.
Classification of muscles:
In medicine, muscles are mainly divided into three types, smooth muscle, skeletal muscle and myocardium.
? 1. Myocardium: It is the muscle that constitutes the heart.
? 2. Smooth muscle: Some muscles of the human body are distributed on the walls of blood vessels or internal organs, called "smooth muscle".
? 3. Skeletal muscle: Skeletal muscle is the most common muscle in human body, mainly distributed in limbs and trunk, and usually connected with bones to operate the activities of limbs, called "skeletal muscle";
Skeletal muscle is also called voluntary muscle, while cardiac muscle and smooth muscle belong to involuntary muscle. Voluntary muscles can be controlled by the brain, but involuntary muscles can't. Muscles mentioned in fitness generally refer to skeletal muscles.
About skeletal muscle:
? Some people may have heard of the so-called "white muscle" and "red muscle". In fact, this difference exists.
? Skeletal muscle fibers can be divided into slow contraction muscle (type ⅰ) and fast contraction muscle (type ⅱ) in function.
? According to the types of skeletal muscle, the types of skeletal muscle fibers can be divided into type A and type B. ..
White muscle (rapid contraction muscle): White muscle fibers are also called fast-moving units.
Structural features:
White muscle fibers are thicker in cross section, so muscle groups are easy to develop and strong. White muscle fibers contain more myofibrils but less myoglobin and cytochrome.
Functional features:
? When exercising, the contraction speed is fast and powerful, the explosive force is strong, but the endurance is poor. Aerobic ability and anti-fatigue ability are high, but glycolysis (anaerobic) ability is poor, contraction speed is slow, and muscle strength per unit exercise is low, which belongs to the muscle type of low intensity and long-term exercise.
The main source of human strength is white muscle, such as lifting heavy objects and lifting weights.
Red muscle (slow contraction muscle): Red muscle fiber is also called slow movement unit.
Structural features:
? Red muscle fibers contain more myoglobin and cytochrome, but less myofibrils.
Functional features:
? During exercise, the red muscle fibers contract slowly and are not explosive, but they can bear hardships and stand hard work. It has the highest glycolysis (anaerobic) ability and exercise unit muscle strength, but its aerobic ability, contraction speed and anti-fatigue ability are poor, and it belongs to the muscle type of high intensity and short time exercise.
The human body mainly participates in red muscle during continuous exercise, such as long-distance running.
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