Hardening of the arteries, also called atherosclerosis, occurs when fat, cholesterol, and other substances build up in the walls of arteries. These deposits are called plaques.efinition. Hardening of the arteries, also called atherosclerosis, occurs when fat, cholesterol, and other substances build up in the walls of arteries. These deposits are called plaques. Over time, these plaques can block the arteries and cause problems throughout the body.
CNS fatigue (CNS = central nervous system) is a slightly more convoluted phenomenon, but the term is thrown around frequently in the world of fitness. By itself, the acronym evokes notions of frailty, complication, and extreme caution.NS fatigue (CNS = central nervous system) is a slightly more convoluted phenomenon, but the term is thrown around frequently in the world of fitness. By itself, the acronym evokes notions of frailty, complication, and extreme caution.
Fatigue is a feeling of tiredness, exhaustion, or lack of energy. You may feel mildly fatigued because of overwork, poor sleep, worry, boredom, or lack of exercise. Any illness, such as a cold or the flu, may cause fatigue, which usually goes away as the illness clears up. Fatigue is a feeling of tiredness or exhaustion or a need to rest because of lack of energy or strength. 2  Fatigue may result from overwork, poor sleep, worry, boredom, or lack of exercise.