LECTURE 6 Flashcards
double ground contact- a foot always on the ground- heel strike
walking
double float phase-mid foot
running
forefoot striking
sprinting
this percent of runners are this?
80%
heel strikers
what is the gait in running?
toe off occurs before 50% of the gait cycle is completed
never a time in running/sprinting that both feet are in contact with the ground at one time
there is a time with both feet are in the air, double float phase
toe off in average runners occurs between what percent of the gait cycle?
world class sprinters toe off as early as at what percent of the gait cycle?
36-39%
22%
absorption and generation in relation to the gait cycle coincide?
T/F
true
BODY’S CENTER OF MASS(BCOM) FALLS
FROM PEAK HEIGHT DURING THE
DOUBLE FLOAT PHASE
THIS PERIOD IS DIVIDED INTO INITIAL
CONTACT INTO SWING PHASE
ABSORPTION
THE VELOCITY OF THE CENTER OF MASS
DECELERATES HORIZONTALLY DURING
THIS PERIOD
what is this, absorption and generation?
absorption
AFTER STANCE PHASE REVERSAL THE CENTER OF MASS IS PROPELLED UPWARD & FORWARD DURING STANCE PHASE GENERATION
KINETIC & POTENTIAL ENERGY INCREASE
what is this generation or absorption?
generation
there is a delay of how many MS between onset of EMG activity and the development of muscle force?
50 ms
Prepares the limb for ground contact
Absorb shock of impact during since phase absorption
Only the this muscle?* is active in midswing
Restrains tibia as knee flexes
Eccentric Motion
what is this muscle?
quadriceps and rectus femoris
*rectus
these muscles EXTEND the hip in 2nd half of swing phase and
first half of stance phase
- Decelerate momentum of tibia as knee extends prior to initial contact
- BIARTICULAR (2 joints)
**concentric & eccentric activity
hamstrings and hip extensors
- hamstrings
- hamstrings
**hamstrings and gastrosoleus
Dorsiflexes the Ankle
Prevents foot slap
Concentric motion
tibialis anterior
these are descriptions of movement and do not consider forces that cause that movement
kinematics
During motion there is a Flexion Shift
Center of mass is lowered from walking, running to sprinting
Pelvic motion should be stabilized for conservation of energy
Increased speed increased horizontal force inPropulsion phase
what is this?
sagittal plane kinematics
Maximum hip extension occurs just before toe off.
Maximum hip flexion occurs in mid to terminal swing
As velocity InCREASES so does maximum hip flexion
Leads to a longer stride length
this along what plane?
sagittal hip plane motion
what is knee motion based on?
sprinting is less time in? and less flexion of what muscle?*
pattern is similar in walking, running and sprinting
degree of motion varies
running absorption phase-45 degrees
generation phase-25 degrees
total ROM, 70 degrees
*absorption, knee flexion
knee motion swing phase, walking running sprinting in degrees?
60, 90, 105 degrees
what plane kinematics?
More Subtle ROM
Minimize upper body motion
Pelvis Stabilized
Hip Adducts relative to pelvis for SHOCK ABSORPTION
Pelvis drops in midstance
Then gins height/stability in generation ( toe off ) phase
coronal plane kinematics
what is this plane kinematics?
Small Magnitude of motion in running
Of ALL three planes this has the LEAST amount of kinematic motion in
running/sprinting
Pelvis rotates forward at initial contact to allow longer stride
Running/Sprinting during swing phase INTERNAL hip ROM occurs
transverse plane kinematics
shoe wear will/not alter the ground reaction forces?
will not, it changers the pressure application to different anatomic structures of the foot
total energy absorbed at this part of the body is greater in sprinting compared to running and walking?
ankle kinematics
knee kinematics?
In second half of swing phase the HAMSTRINGS become dominant
producing knee flexion
Initial Contact the Quadriceps become dominant to provide knee extension
Peak Knee extension is greater in running compared to sprinting
walking efficiency is maintained how?
interchange of potential and kinetic energy
