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.
Central nervous system activation Cortisol levels normally fluctuate throughout the day and night in a circadian rhythm that peaks at about 8 AM and reaches it lowest around 4 AM. While it is vital to health for the adrenals to secret more cortisol in response to stress, it is also very important that bodily functions and cortisol levels return to normal following a stressful event.