The Gait Cycle:

Walking – The Stance Phase

Components of the Stance Phase Stance phase comprises 60% of the gait cycle Heel strike – moment when the heel first strikes the ground Foot flat – from heel strike to when the full foot is in contact with the ground Midstance – body weight is directly over the stance leg Heel off – moment the heel of the stance leg leaves the ground Toe off – when only the toe of the stance leg is in contact with the ground

Walking – The Swing Phase

Components of the Swing Phase Swing phase comprises 40% of the gait cycle Acceleration – the toe of the stance leg leaves the ground and begins to swing forward Midswing – the swinging leg is directly beneath the body Deceleration – the swinging leg continues forward towards knee extension but is slowing down as it travels, stopping just prior to full knee extension and heel contact with the ground

Range of motion at the joints Trunk - As left leg moves forward, pelvis rotates clockwise as viewed from above 7 deg Hip Joint (30 deg flex at HS strike, 180 deg at TO) Stance - extension, adduction, internal rotation Swing - flexion/extension, abduction, ext rotation Knee joint - 180 deg at HS, 160 deg at mid-stance Ankle joint - Neutral at HS, hinges down during support, and plantar flexes at TO . ROM 30 deg COM displacement +5 cm bilaterally and vertically (Fig 15.3)

Running Analysis…... Running is similar to walking BUT, it differs significantly in a number of ways, for example: No period of “double support” Float periods (both feet airborne) Requires greater balance Requires greater strength Requires greater ROM at hip, knee, and ankle joints Involves greater excursion of center of mass Involves greater ground reaction forces

Running – A Gait Cycle

Muscle Activity in Running... Glut. Max. & med. -- active at the beginning of the stance phase (concentrically) and again at the end of the swing phase (eccentrically). Iliopsoas -- active during a portion of the swing phase (concentrically). Quadriceps -- 1st 10% of the stance phase (eccentrically) and last 20% of the swing phase (concentrically). Hamstrings -- initial portion of the swing phase (concentric) and at the end of the swing phase (eccentric). Plantar flexors (gastrocnemius & soleus) – Mid and latter part of stance phase