Gait analysis is the systematic study of human motion, during this process the observer uses his eyes and brain couple with instrument for measuring body movements, body mechanisms, and the activity of the muscles (Levine, et al. 2012) to assess, plan, and treat individuals with conditions affecting their walking abilities. In sports biomechanics it is use to help athletes run more efficiently and to identify posture-related or movement-related problems in people with injuries.
Walking is the most convenient way to travel short distances. Free joint mobility and appropriate muscle force increases walking efficiency. As the body moves forward, one limb typically provides support while the other limb is advanced in preparation for its role as the support limb.
Gait Cycle : is the time interval between two consecutive initial contacts of the same foot for eg first heel strike to the second heel strike. there are phases in each cycle; the stance and swing.
Stance phase is further divided into initial double stance 10% GC, single limb stance (40%), and terminal double limb stance (10%). The sing phase spans the remaining 40% of a GC.
Normal Gait Parameters
Base with : is the distance between the two feet, it ranges from 5-10cm.
Step length : or gait length, is the distance between successful points on opposite feet, about 72cm and usually related to the walking speed.
Stride length : is the linear distance in the plane of progress between successful point of foot-floor contact of the same foot, it is about 144cm, decrease with age, pain, disease, and fatigue.
Lateral Pelvic Shift : or pelvic list is the side-to-side movement of the pelvic during walking. It is about 2-5 cm, and increases if the feet wider apart.
Vertical Pelvic Shift : keeps the center of gravity from moving up and down more than 5 cm.
Pelvic Rotation : is necessary to less the angle of the femur with the floor. It helps to lengthen the femur, decrees the amplitude of displacement along the path traveled by the center of gravity, and hence decrees the center of gravity dip. There is a 4o forward on the swing leg and 4 degree posteriorly on the stance leg, making a total of 8 degree pelvic rotation.
Center of Gravity : in the standing position, lies at about 5 cmterior to the second sacral vertebrae, and a little bit higher in men than in women because men carry a greater body mass in their shoulder area.
Cadence : is the number of steps taken in one minute and it range from 90-120. It about 6-9 steps per minute higher in women than in men and at some age it decreases. (Magee, 2008)
Phase in a normal Gait : each stride contains 8 relevant phases which include:
- Initial contact-heel strike (0-10% GC)
- Loading response-weight acceptance or foot flat
- Midstance-single leg support (10-30% GC)
- Terminal stage-heel off (30-50% GC)
- Preswing-toes off) (50-60% GC)
- Initial swing (60-73% GC)
- Mid swing (73-87% GC)
- Terminal swing (87-100% GC)
The swing phase enterprises of the first five of these phase while the remaining three is for the swing.
Magee, DJ (2008): Orthopedic physical assessment, 5th ed. Saunders Elsevier, Canada. 940-70
Levine, DF; Richards, J., Whittle. M. (2012): Whittle's Gait Analysis Whittle's Gait Analysis Elsevier Health Sciences. ISBN 978-0702042652