text: Chapter 9
  9-30. Any threat, whether it be real or perceived, can result in this sympathetic response. Even non-combat
  stressors such as a physical readiness test, a short-suspense deadline, family stressors, or a difficult commute
  can activate these physiological responses. They are inherently protective, increasing activation, reflexes,
  and chances of survival in life or death situations.
  9-31. One of the hormones released as a result of this protective response is cortisol, often referred to as the
  “stress hormone.” Excessive production of cortisol contributes to chronic disease, poor executive cognitive
  function, and increased susceptibility to injury and infection. When Soldiers are trained to control their
  activation levels, they can mitigate the negative impact of this physiological reaction. It helps Soldiers if they
  can understand how they react to stress at its initial onset. Table 9-2 outlines common physiological acute
  and chronic stress responses.
  Table 9-2. Physiological changes associated with the stress response
  Acute, early phase of the stress response (duration in minutes to hours) symptoms:
   Increased heart rate
   Increased blood pressure
   Increased respiration
   Mobilization of energy from liver and body fat
   Sharpening of attention and cognition
   Increased fear conditioning (learning)
   Blunting of pain
   Altered intestinal motility
   Release of cortisol and adrenaline
  Chronic, later phases of the stress response (duration in days to weeks) symptoms:
   Suppression of immune system
   Suppression of appetite and digestion
   Suppression of growth factors
   Suppression of reproductive factors
   Persistence of increased heart rate and blood pressure for certain cases
   Persistence of increased cortisol levels for certain cases
   Release of stress hormones
   Excessive muscle atrophy (muscle wasting) and redistribution of fat
  HEART RATE CONTROL
  9-32. An effective way to inhibit or enhance the fight or flight response and aide in activation control is by
  monitoring heart rate. Intentional breathing can influence heart rate. By inhaling for a five- to seven-second
  count and exhaling for a five- to seven-second count, Soldiers can slow heart rate, and increase time for
  increased oxygen exchange to take place in the lungs. Soldiers repeat this slow inhalation and exhalation for
  a few repetitions several times per day. Practicing this type of intentional, controlled breathing throughout
  the day improves activation control.
  9-33. Soldiers can practice activation control immediately before or after performance of the target task.
  Adding an activation control skill such as intentional breathing in mid-performance can improve performance
  of the target task by helping to optimize a Soldier’s physiological state when optimal performance is critical.
  The difficulty is incorporating these techniques into deliberate, routine practice so that it becomes a reflex in
  the midst of performing a drill or mission. One technique is simply paying attention to the feeling of air
  moving in and out of lungs for several seconds. This awareness acts as a checkpoint for the performance,
  helping to control breathing and monitoring levels of mental and physical activation. Breathing control is a
  familiar component of several Soldier tasks and can be leveraged for activation control. For example, it is a
  fundamental component of marksmanship.