Before discussing the contraction process itself, let us look first at how muscle fibers obtain the energy they need to contract. The direct source of energy for muscle contraction is ATP. ATP, however, is not stored in large amounts in muscle fibers and is depleted in a few seconds.
The secondary energy sources are creatine phosphate […]

When you walk up a flight of stairs, do you have to look at your feet to be sure each will get to the next step? Most of us don’t (an occasional stumble doesn’t count), and for this freedom we can thank our muscle sense. Muscle sense (proprioception) is the brain’s ability to know where […]

Good muscle tone improves coordination. When muscles are slightly contracted, they can react more rapidly if and when greater exertion is necessary. Muscles with poor tone are usually soft and flabby, but exercise will improve muscle tone.
There are two general types of exercise: isotonic and isometric. In isotonic exercise, muscles contract and bring about movement. […]

Synergistic muscles are those with the same function, or those that work together to perform a particular function. Recall that the biceps brachii flexes the forearm. The brachioradialis, with its origin on the humerus and insertion on the radius, also flexes the forearm. There is even a third flexor of the forearm, the brachialis. You […]

Muscles are arranged around the skeleton so as to bring about a variety of movements. The two general types of arrangements are the opposing antagonists and the cooperative synergists.
Antagonists are opponents, so we use the term antagonistic muscles for muscles that have opposing or opposite functions. The biceps brachii is the muscle on the front […]

Do you like to dance? Most of us do, or we may simply enjoy watching good dancers. The grace and coordination involved in dancing result from the interaction of many of the organ systems, but the one you think of first is probably the muscular system.
There are more than 600 muscles in […]

Muscle tissue is specialized for contraction. When muscle cells contract, they shorten and bring about some type of movement. There are three types of muscle tissue: skeletal, smooth, and cardiac. The movements each can produce have very different purposes.
Skeletal muscle may also be called striated muscle or voluntary muscle. Each name describes a particular aspect […]

Muscle Blood Flow. A key requirement of cardiovascular function in exercise is to deliver the required oxygen and other nutrients to the exercising muscles. For this purpose, the muscle blood flow increases drastically during exercise. A recording of muscle blood flow in the calf of a person for a period of […]

Importance of Maximal Resistance Training. One of the cardinal principles of muscle development during athletic training is the following: Muscles that function under no load, even if they are exercised for hours on end, increase little in strength. At the other extreme, muscles that contract at more than 50 per cent maximal force of contraction […]

The same basic metabolic systems are present in muscle as in other parts of the body. However, special quantitative measures of the activities of three metabolic systems are exceedingly important in understanding the limits of physical activity. These systems are (1) the phosphocreatine-creatine system, (2) the glycogenlactic acid system, and (3) the aerobic system.
Adenosine […]

Phosphocreatine (also called creatine phosphate) is another chemical compound that has a high-energy phosphate bond, with the following formula:
Creatine ~ PO3-
This can decompose to creatine and phosphate ion, as shown to the left in Figure 84–1, and in doing so release large amounts of energy. In fact, the high-energy phosphate bond of phosphocreatine has more […]

There are few stresses to which the body is exposed that even nearly approach the extreme stresses of heavy exercise. In fact, if some of the extremes of exercise were continued for even moderately prolonged periods, they might be lethal. Therefore, in the main, sports physiology is a discussion of the ultimate limits to which […]