Gait Cycle Flashcards
Is this force advantage/ disadvantage? If the fulcrum is closer to the effort?
force disadvantage
Is this force advantage/ disadvantage? If the fulcrum is closer to the load?
force advantage
Which class of lever is force advantage? force disadvantage?
force advantage= 2nd class lever force disadvantage= 3rd class lever
give an example of a 1st class lever.
Ex. joint between head and 1st vertebrae
Ex. scissors, pliers, see-saw
give an example of a 2nd class lever.
Ex. wheelbarrow, stapler, bottle opener, nutcracker
Ex. standing on tiptoes
give an example of a 3rd class lever
Ex. biceps curl
Ex. fishing rod, tweezers, tongs
What is Newton’s 1st law of motion?
(law of inertia)
a particle at rest , or moving in a straight line with a constant velocity, will remain in its state provided it is not subjected to an unbalanced force
what is Newton’s 2nd law of motion?
(law of acceleration)
a particle acted upon by an unbalanced force experiences an acceleration that has the same direction as the force and a magnitude that is directly proportional to the force ; (F=ma)
what is Newton’s 3rd law of motion?
(law of action-reaction)
the mutual forces of action and reaction between two particles/bodies are equal, opposite, and co-linear.
explain this mechanical analysis method: direct dynamics (forward mechanics).
mechanical analysis of a system that determines movement from forces
Ex. using force plates to record forces
explain this mechanical analysis method: inverse dynamics.
mechanical analysis of a system that determines force from movement
Ex. using video-based motion analysis
what is the frontal plane movement for ankle, knee, and hip during the gait cycle?
ankle- inversion
knee- valgus
hip- abduction
what percentage of the gait cycle is spent in stance phase?
60%
what percentage of the gait cycle is spent in swing phase?
40%
what percentage of the gait cycle is spent in double support? and when?
20% - there are 2 periods: 0-10% and 50-60%
what percentage of the gait cycle then is spent in single-support?
80%
what is normal gait speed?
1.4 m/s (3mph)
what is normal step rate?
- 9 steps/s (110 steps/min)
what is normal step length?
72 cm (28 inches)
what is the term for the sequence of events taking place between successive heel contact of the SAME foot?
stride (or gait cycle)
what is the term for the sequence of events that occurs with successive heel contacts of the OPPOSITE foot?
step
what is stride length?
distance btwn two successive heel contacts of the SAME foot
what is step length?
the distance btwn two successive heel contacts of DIFFERENT feet
*recall that normal step length is 72 cm (28 in)
what is step width?
lateral distance btwn the heel centers of 2 consecutive foot contacts
*normal step width is 7-9cm
what is foot angle?
“the degree of turnout”; the angle between the line of progression of the body and the long axis of the foot
*normal foot angle is about 7 degrees
name the temporal descriptors of gait.
cadence (or step rate)
stride time
step time
what is cadence?
of steps per minute
what is stride time?
the time for a full gait cycle
what is step time?
the time for completion of a right or left step
of all the spatial and temporal measures of gait, what is the best measure of an individual’s walking ability?
walking speed
all measurements of gait depend on what?
walking speed
what are 2 strategies to increase walking speed?
- increasing stride or step length
2. increasing cadence
which part of the gait cycle is affected when gait speed increases?
double-limb support (time spent in this phase will DECREASE)
what happens to % of gait cycle spent in double limb support as gait speed increases?
% of gait cycle spent in double-limb support DECREASES
what happens to stride length in the elderly?
stride length decreases
what happens to stride length with increased speed?
stride length increases
what happens to double support time with increased speed?
decreased double support time
what happens to double support time in the elderly or in patients with balance disorders?
double support time increases
what is considered slow speed/cadence?
<70 steps/min
what is consdiered fast speed/cadence?
> 120 steps/min
what is typical/comfortable speed?
80-110 steps/min
what are the 2 reduction of energy mechanisms to reduce vertical excursion by limiting downward displacement of CoM?
- horizontal plane pelvic motion
2. sagittal plane ankle motion
what are the 2 reduction of energy mechanisms to reduce vertical excursion by limiting upward displacement of CoM?
- stance phase knee flexion
2. frontal plane pelvic rotation
what is the mechanism that reduces medial-lateral excursion to save energy?
frontal plane hip rotation- reducing step width
How do women compare to men in terms of walking speed, step length, and cadence?
women exhibit a slower walking speed, shorter step length, and faster cadence than men.
When is minimum and maximum kinetic energy reached in the gait cycle?
min. KE is reached at mid-stance for both legs (30% and 80% of gait cycle )
max. KE is reached at double-limb support (5% and 55%)
when is minimum and maximum potential energy reached in the gait cycle?
min. PE is reached at double-limb support (5% and 55%)
max. PE is achieved when CoM reaches its highest points (30 and 80%)
