LECTURE 6

Question 1

double ground contact- a foot always on the ground- heel strike

Answer 1

walking

Question 2

double float phase-mid foot

Answer 2

running

Question 3

forefoot striking

Answer 3

sprinting

Question 4

this percent of runners are this?

Answer 4

80%

heel strikers

Question 5

what is the gait in running?

Answer 5

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

Question 6

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?

Answer 6

36-39%

22%

Question 7

absorption and generation in relation to the gait cycle coincide?

T/F

Answer 7

true

Question 8

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?

Answer 8

absorption

Question 9

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?

Answer 9

generation

Question 10

there is a delay of how many MS between onset of EMG activity and the development of muscle force?

Answer 10

50 ms

Question 11

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?

Answer 11

quadriceps and rectus femoris

*rectus

Question 12

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

Answer 12

hamstrings and hip extensors

• hamstrings
• hamstrings

**hamstrings and gastrosoleus

Question 13

Dorsiflexes the Ankle

Prevents foot slap

Concentric motion

Answer 13

tibialis anterior

Question 14

these are descriptions of movement and do not consider forces that cause that movement

Answer 14

kinematics

Question 15

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?

Answer 15

sagittal plane kinematics

Question 16

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?

Answer 16

sagittal hip plane motion

Question 17

what is knee motion based on?

sprinting is less time in? and less flexion of what muscle?*

Answer 17

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

Question 18

knee motion swing phase, walking running sprinting in degrees?

Answer 18

60, 90, 105 degrees

Question 19

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

Answer 19

coronal plane kinematics

Question 20

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

Answer 20

transverse plane kinematics

Question 21

shoe wear will/not alter the ground reaction forces?

Answer 21

will not, it changers the pressure application to different anatomic structures of the foot

Question 22

total energy absorbed at this part of the body is greater in sprinting compared to running and walking?

Answer 22

ankle kinematics

Question 23

knee kinematics?

Answer 23

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

Question 24

walking efficiency is maintained how?

Answer 24

interchange of potential and kinetic energy

Question 25

lost energies converted to what kind of potential energy?

Answer 25

elastic potential energy and stored in muscles, tendons and ligaments

Question 26

Transfer energy from moving tibia to pelvis to aid in hip extension, what is this concept called?

Answer 26

energy strap