POSTECH H uman S ystem D esign Lab oratory Stair ascent and descent at different inclinations Robert Riener et al. (2002, Italy and Germany) Gait and Posture

POSTECHHuman System Design Laboratory

StairStair ascent and descentascent and descentat different inclinationsat different inclinationsRobert Riener et al. (2002, Italy and Germany)

Gait and Posture

2009. 7. 28. Tue.Heo, Jiyoon


ContentsContents

1. Introduction2. Methods3. Results4. Discussion

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1. Introduction1. Introduction

Objectives

To face the question of how staircase inclination affects the kinematic

and kinetic patterns of stair climbing

To ascertain if ascent and descent patterns are to be considered as

particular evolution of the level walking pattern.

Expected effects

Adding to our understanding of the diverse and complicated process

involved in human locomotion

Designing of private and public environments where stairs are employed

Using in the field of gait rehabilitation

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1. Introduction1. Introduction

Literature survey

To investigate normal human stair ascent and descent

• “a study of lower-limb mechanics during stair climbing” (Andriacchi et al., 1980), etc.

To investigate focused on joint moments

• “Aduction–adduction moments at the knee during stair ascent and descent.” (Kowalk et al., 1996)

To investigate focused on joint powers

• “Six degree of freedom joint power in stair climbing” (Duncan et al., 1997)

To investigate focused on plantar pressure characteristics

• “Plantar pressure characteristics during stair climbing and descent” (Wervey et al., 1997)

To investigate focused on reproducibility

• “Reproducibility of the kinematics and kinetics of the lower extremity during normal stair-climbing”

(Yu B et al., 1997)

To investigate stair climbing of patients with knee and hip implants

• “The influence of total knee-replacement design on walking and stair climbing” (Andriacchi et al.,

1982), etc.

No comprehensive analysis is available in the literature that discusses biomechanics of stair

ascent and descent at different inclinations

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Instrumented staircase design

Composed of 4 steps and a platform at the upper end

Adjustable in height

• 24˚: 13.8 X 31.0 cm (riser X tread)

• 30˚: 17.0 X 29.0 cm

• 42˚: 22.5 X 25.0 cm

The lower 3 steps were instrumented with six strain-gauge force transducers each

Camera-based movement analyser

(ELITE, BTS Milan, Italy)

Measurements

GRF

The vertical component of the GRM

Joint angles

Cycle time

2. Methods2. Methods

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Subjects

10 healthy males

• Height: 1.79 ± 0.05 m

• Weight: 82.2 ± 8.5 kg

• Age: 28.8 ± 2.9 years

Free of any musculo-skeletal or neurological dysfunction

Protocols

The subject walked barefoot at normal, comfortable speed.

Prior to data acquisition, the subjects accustomed to the stair motion.

The subjects did 5 repetitive trials at each conditions.

Ascent stride cycle: foot contact on 2nd step ~ 4th step

Descent stride cycle: foot contact on 3rd step ~ 1st step

Foot contact always occurred with the same foot


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Data of level walking

From 26 healthy male subjects (similar) were taken out of the data bank of

the Centro di Bioingegneria gait laboratory.

• Height: 1.80 ± 0.06 m

• Weight: 76.7 ± 9.4 kg

• Age: 27.2 ± 2.6 years

Data processing

Hip and knee angle: computed in sagittal projection.

Ankle joint angle: computed in plane (dorsiflextion / plantarflexion)

Angular velocities and accelerations: first and second derivatives of the joint

angle data

Anthropometric parameters: estimated by regression equations (Zatsiorksky

and Seluyanov, 1983)

Segment lengths: directly measured

Mechanical power at each joint: the product of joint moment and angular

velocity


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Gait cycle parameters

Ascent: stance duration increased only slightly with stair inclinations

Descent: stance duration percentage progressively decreased with

increasing inclinations

Stride cycle duration: ascent (1.43 s) > descent (1.20 s)

3. Results3. Results

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Kinematics – foot placement

‘-’ sign means that the subject contacted the step with forefoot.

Ascent: independent from inclination

Descent: distinctly related with inclination


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Kinematics – joint angles


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Ascent Descent

Foot contact(0% cycle time)

Hip: flexedKnee: flexedAnkle: dorsiflexed

Hip: slightly flexedKnee: almost extendedAnkle: plantarflexed

Subsequent phaseHip/Knee: extendedAnkle: plantarflexed

Hip/Knee: flexedAnkle: dorsiflexed plantarflexed

Ranges Maximum flexion angles increased with increasing inclination

Compared w/ level walking

Clearly distinguished (ex; Angular ranges)

※ gray column in graph means toe-off phase


Ground reaction forces


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Ascent Descent

Producedforces

Relatively small Relatively large

Influence of inclination

Relatively small(sig. dependency was only in the vertical component during early descent stance. Increased 14.8%)


Preserved most of the features


Joint moments


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Ascent Descent

Momentsin stance phase

Hip: extension momentsKnee: (2nd half) decreased

Hip: flexion momentsKnee: (2nd half) increased

Influence of inclination

Not sig. dependency - during swing phase- first half stance phase of knee jointSig. dependency- max. moment: hip (ascent), knee, ankle(early phase)


Different



Joint powers


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Ascent Descent

PowerProducing energy during most phase (+)

Predominantly, energy was absorbed (-)

Influence ofinclination

More dependent on staircase inclination than joint angles and moments

Compared w/level walking

Some similarities (ex; ankle late stance, hip early stance)Some differences: Knee (3.8 times difference during descent)



Differences between ascent and descent

Fundamental consideration (McFadyen and Winter, 1988)

• The ascending task consists primarily of a transfer of muscle energy into potential

energy of the body

• During descent, the potential energy has to be dissipated (absorbed) by the muscle

consequence:

• During loading response phase (pull up): forces in descent > forces in ascent

• During phase of energy production (push up): forces in descent < forces in

ascent

※ if we consider that 50% of the ipsilateral stride cycle corresponds to the initial contact of the

contralateral side : push up at ankle joint pull up at knee and hip joints

※ Note that during these phases, the antigravity muscles perform eccentric contractions (they generate

force while they are lengthened).

Be a potential risk of muscle fiber damage

4. Discussion4. Discussion

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Influence of staircase inclination

Significant dependency of most gait parameters on staircase inclination

• Angular ranges of all joints, Joint power patterns (Muller et al., 1998), GRF

But the intensity of this dependency was different

• Only little influence on gait phase parameters(tab 1.), and joint moment patterns(fig 4.)


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Comparison with level walking

One can assume that ascending and descending motions are to be

considered as particular evolution of level walking.

Only little signs could be found that indicate an adaptation or shift in the

motor patterns when moving from level to stair walking

- vertical GRF, some joint powers (partly at hip and knee)

The typical sharing of energy absorption among the leg joints was not

observed during level walking

The gait patterns did not change in a progressive way.

• In most cases, the intersection of the extrapolated linear regression with the

vertical line at 0˚ inclination clearly deviated from the characteristic values

observed at level walking.

• The subjects contacted the steps with forefoot during climbing.


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Documents

POSTECH H uman S ystem D esign Lab oratory Stair ascent and descent at different inclinations Robert Riener et al. (2002, Italy and Germany) Gait and Posture