NLAAF Definitions
Maximizing ground contact: getting the most return out of forces applied
Synergistic movements: arm and legs, shoulders and hips, hand and feet, elbows and knees
Ground contact: period when any part of the foot comes in and stays in contact with the ground
Ground contact time: the length of time the foot stays in contact with the ground, be it artificial or natural.
Initial contact phase: when any part of the foot comes into contact with the ground before the loading phase begins; start of ground contact
Positive Speed: speed of a body segment in the direction of movement
Negative Speed: speed of a body segment in the opposite direction of movement
Frontside Mechanics: movement of body segments (arms and legs) occurring in front of the body as viewed from the side
Backside Mechanics: movement of body segments (arms and legs) occurring behind the body as viewed from the side
Active foot strike and landing: foot movement towards the body prior to initial ground contact
Eccentric or Load Bearing Phase: when the downward forces of the body are absorbed by the joints and muscles of the leg or by the foot and plantar fascia
Isometric or Support Phase: when the joints and muscles of the leg or plantar fascia have fully adsorbed or bottomed out from the downward forces of the body
Stride Length: distance traveled by hips from unloading to loading phase
Stride Reach: distance from heel of foot to leg at the start of the unloading phase, the greater the distance the longer the stride length will be
Positive Foot Velocity: speed at which the foot is accelerated from the backside to the front side or up or both
Negative foot velocity: speed at which foot is accelerated from the front to the rear or downward or both
One Sided: arm stroke per two strides
Two Sided: arm stroke for each stride
High foot: distance foot is off the ground before starting downward, not a function of knee lift
Dorsi Flex Toes: upward lift of the toes with the foot on or off the ground
Plantar Flex: downward position of the foot
Dorsi-Plantar Combo Flex: the upward lift of the toes with the downward movement of the foot
Ball of Foot: the section of the foot between the metatarsal phalanges joint and the head of the metatarsal
Knee to Hip Extension: when the knee joint holds steady as the hip moves over it to the front
Stiff Leg: when there is no give between ankle joint and hip joint during load phase; knee can be bent at initial ground contact through load phase
Non-Stiff Leg: when the ankle, hip and knee joints give or collapse at initial ground contact through load phase
Vertical displacement of hips, positively and negatively: the movement, on the vertical axis, of the hips from rebound phase to support phase
Support phase: the time period that neither downward nor upward movement of the hip joint is occurring
Unloading or Concentric Phase: begins when the support phase ends and the upward motion of the hip joint begins, ends at toe off
Segmental Sequential Arm Movement (SSAM): hands and arms move in a set pattern for the up stroke and down stroke. Hand and arm movement assists and affects legs and feet recovery speed.
Windlass effect: the tightening of the plantar fascia due to dorsi flexing of the toes
Windlass mechanism: the shock absorbing and rebounding properties of the plantar fascia
