Endocrine System

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Why does Muscular Fatigue develop?

9.6     The causes of muscular fatigue are not well understood. One explanation is that when muscles contract they produce lactic acid. Lactic acid creates an environment in which muscles are not able to respond to stimulation. However, new research indicates that there are other contributing factors, such as depletion of stored energy and muscle glycogen, inadequate blood flow to the muscles, and low oxygen levels. Well-conditioned athletes experience less muscle fatigue. It is known that they accumulate less lactic acid in their muscles and that conditioning actually increases the capillary density of the skeletal muscles, increasing blood flow.

 Why does Weight Training make a Person look Muscular?

9.7     Muscles develop differently depending on the type of exercise they receive. For example, when a muscle is contracted moderately but repeatedly, as in swimming, it develops new capillaries and some increased strength. When a muscle is contracted in short, forceful actions, as in weightlifting, the muscle fibres increase in diameter and the entire muscle enlarges more than in repeated, moderate activity. This form of exercise increases the strength of the muscle, but a weight lifter wil not have the endurance of a swimmer.

 What does it mean if a Person has Temporomandibalar Joint Syndrome (TMJ)?

9.8     Stress or a poor bite (malocclusion of the teeth) can cause some people to clench their jaw, especially in their sleep. Contracting the jaw muscles in this way causes pressure on the temporomandibular joint located in the jaw just below the ear. This can result in headaches, earaches, or pain in the jaw, neck, or shoulder. This condition is called temporomandibular joint syndrome, or TMJ. Stress management and dental splints are often prescribed for sufferers of TMJ.