text: PART TWO
  Design
  Part Two explains the scientific basis of Soldier performance and how the H2F training
  program is designed. Training approaches described in Part Two address the “why” of
  H2F—the science and rationale behind the program. The principles discussed in Part
  Two form the approaches used in Part Three to build H2F program content for
  individual Soldiers and collective unit readiness and deployability.
  Chapter 4
  Physiology
  The effectiveness of Soldiers depends largely on their physical condition. Combat
  places a premium on the Soldier’s strength, endurance, and lethality. Victory depends
  on these physical attributes. Leaders also recognize that the mind controls the body.
  Therefore, to persevere in battle and thrive afterward requires an equal measure of
  psychological health—mental toughness, stamina, emotional fortitude, intellect,
  judgment, strength of character, and spirituality. The requirement to train all these
  domains—physical readiness, nutritional readiness, mental readiness, spiritual
  readiness, and sleep readiness—has become more urgent. The inputs that Soldiers and
  units will be required to process, and the time to process and act upon them will be
  inversely proportional. Therefore, the capacity of the unit to be successful rests upon
  every Soldier’s ability to respond effectively in the absence of complete information
  or on short notice. Collective capacity depends on this individual ability. Underpinning
  all is an understanding of how the human body works—its anatomy and physiology.
  SOLDIER PHYSIOLOGY
  4-1. Physiology is the study of the functions and parts of a living organism. This section describes the
  physiological and anatomical foundation of Soldier performance.
  4-2. When the predecessor to the ACFT, the three-event Army Physical Fitness Test (known as the APFT)
  was developed in the midst of the Cold War, some senior Army leaders felt ground combat was no longer a
  force imperative. As a result, the Army replaced rigorous physical training and assessment linked to the
  performance of occupational warfighter tasks with more general fitness training and assessments. This
  approach mirrored civilian trends with aerobics and jogging driving the popularity of endurance-centric
  fitness. The three-event Army Physical Fitness Test along with the Army Weight Control Program were
  developed to ensure a high level of health-related fitness and appropriate body mass.
  4-3. The lessons learned over three decades of combat operations renewed the Army's focus on the strength
  and power requirements for ground combat. In 2013, under HQDA directions, the Army began two major
  physical fitness assessment studies: (1) Army Required Actions in Support of the Elimination of the Direct
  Ground Combat Assignment Rule (DGCAR), and (2) Comprehensive Study to Determine Baseline Soldier