ADVANCEDBIOMECHANICS

HPE 660

Luke Hopper

Introduction to Gait Analyses

Temporal parameters of the gait cycle

General kinematics and kinetics

Treadmill gait analysis

Today’s Lecture and Lab

Evolutionary Adaptations for Human Endurance Running

Anatomical adaptations Bipedalism places COM directly over

base of support Tendon length and size enable energy

storage Longitudinal foot arch for shock

absorption and energy storage Enlarged knee joint articular surfaces Gluteus maximus size

Evolutionary Advantages for Human Endurance Running

Bramble & Lieberman, 2004. Endurance running and the evolution of Homo. Nature, 432, 345-52

Relatively slow max speed Human jogging range beyond trot to gallop transition

of small to medium quadripeds

Quadriped panting capacity

reduced during galloping Hunting success may have

improved over long distance

Walking

Inverted pendulum model Translation strategy of movement Energy and force dissipated through

bones and joint tissue COM height increases

during mid stance

RunningMass spring model Leg obeys stiffness properties

of a spring

Stiffness = Force/distance = Nm-1

Compression of leg reacts to opposing JRF and GRF

VGRF and braking forces result in spring compression and energy storage

COM vertical displacement behaves in opposition to walking

Blickhan, 1989. The spring-mass model for running and hopping. Journal of Biomechanics. 22 (11-12), 1217-27.

Human gait cycle

Stance phaseFoot contact (footstrike) until foot leaves the

ground (toe-off) Swing phase

Toe-off to footstrike Stride

Toe-off to ipsilateral toe-off Step

Toe-off to contra lateral toe-off (footstrike to contra lateral footstrike)

Human gait cycle

Walking:Alternating single

and double leg support

Running:Alternating

sequences of support and non-support

Data from Vaughan 1984.

Notice stance phase decreases as speed increases

Temporal-Spatial Parameters (TSP’s) Walking speed

Distance/time(Cadence x stride length)/ 120

CadenceNumber of steps per minute (divide by 120

to get strides/second) Stride length

(120 x speed)/cadenceSpeed x stride time

Normative data for “TSP”

Other factors which influence TSP:Shoes vs No shoes

○ Longer support barefootAgeTreadmill

○ Stride length ↓○ Cadence ↑

Speed (m/s) Cadence (steps/min)

Stride length (m)

Men 1.3-1.6 110-115 1.4-1.6

Women 1.2-1.5 115-120 1.3-1.5

Effect of speed on time, phase & stance

Implications for force development?

(b) Adapted from J. Nilsson and A. Thorstensson 1987.

Kinematics of running speed... SL for initial

increase in speed SR later SL increases

require less energy Trained athletes are

able to maximise SL Data from Saito et al. 1974.

Trained

Untrained

Kinematics with speed...

Knee joint kinematics change with speed increase

Greater flexion during swing and at IC

Consider walking and running models

Data from C.L. Vaughan 1984.

Shaded area = stance phase (IC to TO

0 rad = extension at knee

General kinematics and muscle activation during walking

Whittle, M. (2007). Gait analysis: an introduction. Philadelphia: Elsevier.

Kirtley, C. (2006). Clinical gait analysis: Theory and practice. Philadelphia: Elsevier.

2-D Analysis of gait kinematics Can give some

quick valuable information but the downfalls include:Parallax error

○ Movement away from the optical axis of the camera

○ Increase toward periphery

2-D Analysis of gait kinematics (2)

Perspective errorOut-of-plane movement causes an apparent change in

lengthReduced by increasing camera distance and zooming in

to compensate for subject size

Segment length (l) is reduced by amount (e) when it moves distance (d)

GRF during normal walking gait Rise and fall above or

below BW = extra accelerationA = IC rises quicklyB = above BW early in

stance phaseC = below BW in mid-

stanceD = terminal support,

transfer to contra lateral limb

E= swing phase Winter, 1991

Shear components during normal gait

Be familiar with shearing forces FAP

○ Smaller than vertical○ Posterior (braking) for

1st 50% of stance and anterior (propulsive) late stance

FML

○ Medially in response to lateral motion of body

○ Size proportional to stride width

Speed and AP shear force Closely related to stride length Braking AP shear (in % BW) = 31 – normalized SL x 8.36 Propulsive AP shear = 30 x normalized SL – 6.4

r2 = 0.99

The double support phase Sum of GRF from

each side Normally smooth

pattern is irregular in double support

GRF of L and R are not necessarily symmetrical even in healthy populations