Week 12: gait

Question 1

Gait cycle

Answer 1

 One stride (one gait cycle)
is the period from foot
contact (typically with the
heel) on one leg to the
next foot contact on the
same leg
 A step (half a gait cycle) is
the period from foot
contact on one leg to the
next foot contact on the
opposite leg
 One stride can be divided into two phases:
 the stance phase and the swing phase

Question 2

Support phases

Answer 2

 Stance phase consists of two periods of ≈10% where
both feet are in contact with the ground (double
support) and one intervening period of ≈40% where one
foot is in contact with the ground (single support)

Question 3

Forward progression is the goal

Answer 3

The stance phase must:
 provide adequate support to avoid a fall
 Attenuate / absorb the load experienced at foot contact
 provide the necessary propulsive force to allow forward
progression
The swing phase must:
 allow safe foot clearance
 ensure the appropriate limb placement for the next foot
contact

Question 4

Ankle-foot complex

Answer 4

 After ground contact in typical
walking gait two opposing
vertical forces acting on either
side of the axis of rotation in the
subtalar joint create eversion of
the rearfoot
 This pronation of the ankle-foot
complex “unlocks” the transverse
tarsal joint and makes the foot
more mobile so that it can adapt
to the walking surface

Question 5

Load attenuation mechanism (1)

Answer 5

 Pronation of the ankle-foot complex is accompanied by
internal rotation of the tibia (because the foot is fixed to
the ground) and this helps to promote knee flexion
 Some of the load is attenuated through knee flexion
which is controlled eccentrically by the knee extensor
muscle group

Question 6

Load attenuation mechanism (2)

Answer 6

 As body weight is progressively transferred onto the
stance foot the medial longitudinal arch slowly lowers,
the plantar aponeurosis and spring ligament are
stretched and energy is stored within these structures

Question 7

Forward progression is the goal

Answer 7

The stance phase must:
 provide adequate support to avoid a fall
 Attenuate / absorb the load experienced at foot contact
 provide the necessary propulsive force to allow forward
progression
The swing phase must:
 allow safe foot clearance
 ensure the appropriate limb placement for the next foot
contact

Question 8

Mechanism (1)

Answer 8

 A concentric contraction
of the ankle plantar
flexors may “push” the
leg forward into swing

Question 9

Mechanism (2)

Answer 9

 A concentric contraction of
the hip flexors may “pull”
the leg forward into swing

Question 10

How does the foot prepare?

Answer 10

 (1) The ankle-foot complex supinates and this “locks” the
transverse tarsal joint and causes the foot to become rigid
15
 (2) Extension of the hallux
(particularly when combined with
ankle plantar flexion) pulls the
plantar aponeurosis taut. This
raises the arch and stabilises the
foot further = windlass mechanism

Question 11

Ankle “push-off”

Answer 11

 Muscles such as gastrocnemius and soleus use this
stability to transfer forces from the achilles tendon,
through the midfoot, to the metatarsal heads during the
propulsive phase

Question 12

Forward progression is the goal

Answer 12

The stance phase must:
 provide adequate support to avoid a fall
 Attenuate / absorb the load experienced at foot contact
 provide the necessary propulsive force to allow forward
progression
The swing phase must:
 allow safe foot clearance
 ensure the appropriate limb placement for the next foot
contact

Question 13

Three (3) mechanisms for foot clearance

Answer 13

 (1) Knee flexion (initiated in part by gastrocnemius)
 (2) Rapid ankle dorsi-flexion
 Concentric contraction of the dorsi-flexors (a neutral position is
reached by mid swing and is maintained during the rest of the
swing phase until the next heel strike)

Question 14

Three (3) mechanisms for foot clearance

Answer 14

 (3) Controlling / minimizing
the amount of hip adduction
on the stance limb side
 Which muscle group on which side is
responsible for this?

Question 15

Basic measures of gait (temporal-spatial parameters)

Answer 15

 Walking speed, cadence and stride length are
collectively referred to as temporal-spatial parameters
 Walking speed is the relationship between the time taken to
cover a certain distance
 Cadence is the number of steps per minute
 Cadence is an old term that doesn’t conform to standard SI units so there is
currently a push to replace cadence with stride time - Stride time is the time
to complete one stride
 Stride length is the distance covered during one stride

Question 16

Temporal-Spatial Parameters

Answer 16

 No consensus on ‘typical’ values for a given population
 Values will differ depending upon the environment (e.g. walkway
length, indoor v outdoor) and method (e.g. protocol, instrument, operator)
 There is also natural variability both within and between individuals

In general temporal-spatial parameters may be used to:
 screen individuals (e.g. to detect elderly people at risk of falling)
 measure performance (e.g. to grade a patient’s level of disability)
 monitor the efficacy of a therapy or intervention (pre-post test)

Question 17

Characteristics of early gait

Answer 17

 The main differences between the gait patterns of
toddlers (15 months) and adults are:
1. The walking base is wider
2. The stride length is shorter, the
cadence is higher, and the walking
speed is slower
3. Initial contact is made with the sole of
the foot (foot flat) rather than the heel
4. There is very little stance phase knee
flexion
5. The whole leg is externally rotated
during swing
6. There is an absence of reciprocal arm
swinging

Question 18

Development of adult gait (by age 2)

Answer 18

1. The walking base is wider
2. The stride length is shorter, the cadence is
   higher, and the walking speed is slower
3. Initial contact is made with the heel
4. A typical pattern of stance phase knee flexion
   is developing
5. There is a typical pattern of swing phase hip
   rotation
6. There is an absence of reciprocal arm swinging

Question 19

Development of adult gait (by age 4)

Answer 19

1. The walking base width is typical of adult gait
2. The stride length is shorter, the cadence is
   higher, and the walking speed is slower
3. Initial contact is made with the heel
4. There is a typical pattern of stance phase knee
   flexion
5. There is a typical pattern of swing phase hip
   rotation
6. There is reciprocal arm swinging

Question 20

Age 7 & up

Answer 20

 Small changes in stride length, cadence and walking
speed will continue to occur with skeletal growth and
development (e.g. limb length) until these processes are
completed

Question 21

Ageing

Answer 21

 The overriding goal is forward progression
The stance phase must:
 provide adequate support to avoid a fall
 absorb the load at foot contact
 provide the necessary propulsive force to allow
forward progression
The swing phase must:
 allow safe foot clearance
 ensure the appropriate limb placement for the next
foot contact

Question 22

Ageing

Answer 22

 Age related changes in gait are typically
observed during the 7th decade (60-70 years)
 The most commonly observed change is a
decline in walking speed
 ≈ 0.1-1.2% per year from the seventh decade of life
There may also be a:
 decreased stride length (due to hip flexion contracture)
 variable but generally decreased cadence
 increased walking base width

Question 23

Changes to propulsion with ageing

Answer 23

 There is considerable evidence to suggest that older
individuals display a reduced relative contribution from
the ankle plantar-flexors.
A deliberate strategy (‘under-utilisation theory’) (Franz, 2016) to perhaps
maintain greater foot-floor contact at the end of stance and
broaden the base of support – improve balance control (Barak et al.,
2006)
ALTERNATIVELY
 Concentric muscle weakness (Porter et al., 1997) - SARCOPAENIA
 Reduced hip extension range of motion which does not allow the
leg to adopt a position that facilitates ankle plantar-flexion

Question 24

Compensation

Answer 24

 The muscles of the hip would appear to be best
suited to compensate for the reduced role of the
ankle plantar flexors
SPX 201 Functional Anatomy 33
 (1) A greater relative contribution
from the hip flexors “pulling” the
leg into swing

Question 25

Falls

Answer 25

 Falls are the most common accident in the old
and ≈ 45% of them occur during walking. About
5% of these result in major injuries (e.g.
fractures) requiring medical care (AGS, 2001)
 Falls are a major public health issue:
financial cost of surgery and rehabilitation
human cost of pain, disability, & loss of independence
 Falls may result from trips or slips

Question 26

Trips

Answer 26

 There is generally no difference in minimum foot
clearance (MFC) between young and old
individuals (Barrett et al., 2010)
 Young and old individuals may use different
strategies to achieve a similar foot clearance
(Mills et al., 2008)
 Foot clearance was most sensitive to changes in
the position of the ankle, followed by the hip,
then the knee
 Old individuals exhibit greater inter-stride variability in
MFC compared to young individuals (Barrett et al., 2010)
 may be related to a disruption in the coordination of the segments
of the lower extremity, reduced proprioception, or reduced
capacity to control muscle force production

Question 27

Slips

Answer 27

 Slips generally occur shortly after heel contact at
the commencement of the stance phase
 Old individuals:
 (1) exhibit a higher heel contact velocity (e.g. Mills & Barrett
2001) which may be related to delayed and reduced
hamstring muscle activation (Prince et al., 1997)
 (2) have a slower transition of the whole body centre
of mass over the stance limb