Conventions for naming parts of the gait cycle
This course employs the widely used terminology developed at the
pathokinesiology laboratory of Rancho Los Amigos Hospital.
The gait cycle begins when one foot contacts the ground and ends
when that foot contacts the ground again. Thus, each cycle begins
at initial contact with a stance phase and proceeds through a
swing phase until the cycle ends with the limb's next initial contact. Stance phase accounts for approximately 60 percent, and swing phase for approximately 40 percent, of a single gait cycle.
Each gait cycle includes two periods when both feet are on
the ground. The first period of double limb support begins at initial contact, and lasts for the first 10 to 12 percent of the cycle. The second period
of double limb support occurs in the final 10 to 12 percent of stance phase. As the stance limb prepares to leave the ground, the opposite
limb contacts the ground and accepts the body's weight. The two periods of double limb support account for 20 to 24 percent
of the gait cycle's total duration.
Stance phase of gait is divided into four periods: loading
response, midstance, terminal stance, and preswing. Swing
phase is divided into three periods: initial swing, midswing,
and terminal swing. The beginning and and ending of each period are defined by specific events.
STANCE PHASE:
- Loading response begins with initial contact,
the instant the foot contacts the ground. (Normally, the heel
contacts the ground first. In patients who demonstrate pathological
gait patterns, the entire foot or the toes contact the ground
initially.) Loading response ends with contralateral toe off,
when the opposite extremity leaves the ground. Thus, loading
response corresponds to the gait cycle's first period of double
limb support.
- Midstance begins with contralateral toe off and ends
when the center of gravity is directly over the reference foot.
(Note that this phase, and early terminal stance, the phase discussed
next, are the only times in the gait cycle when the body's center
of gravity truly lies over the base of support.)
- Terminal stance begins when the center of gravity is
over the supporting foot and ends when the contralateral foot
contacts the ground. During terminal stance, around 35 percent
of the gait cycle, the heel rises from the ground.
- Preswing begins at contralateral initial contact
and ends at toe off, at around 60 percent of the gait cycle.
Thus, preswing corresponds to the gait cycle's second
period of double limb support.
SWING PHASE
- Initial swing begins at toe off and continues
until maximum knee flexion (60 degrees) occurs.
- Midswing is the period from maximum knee flexion
until the tibia is vertical or perpendicular to the ground.
- Terminal swing begins where the tibia is vertical and
ends at initial contact.
References:
Gage, J.R. (1990). An overview of normal walking. Instructional Course Lectures, 39,, 291-303.
Observational Gait Analysis Handbook. (1989). Downey, CA: Professional Staff Association of Rancho Los Amigos Medical Center.
Perry, J. (1990). Pathological gait. Instructional Course Lectures, 39, 325-331.
Web sites that maintain useful moving images of the walking cycle:
Kirtley, C. (2002). Clinical gait analysis. Clinical cases. Retrieved March 18, 2002 from http://guardian.curtin.edu.au/cga/case.html
Many of the cases archived at this site include brief moving images of people with gait disorders.
McGill University. Molson Medical Informatics Project. (1999). Normal gait. Retrieved March 18, 2002, from http://sprojects.mmi.mcgill.ca/gait/normal/movie2.asp
Medical College of Ohio. Center for Creative Instruction. (2001). Observational gait analysis. Gait Animation movie. Retrieved March 18, 2002, from http://www.mco.edu/cci/gait.html