A biomechanical evaluation of staircase riser heights and tread depths during stair-climbing

Clinical Biomechanics

1987; 2: 162-164

Printed in Great Britain

A biomechanical evaluation of staircase riser heights and tread depths during stair-climbing A Mital PhD H F Fard MS, H Khaledi

MS

Ergonomics Research Laboratory, College of Engineering,

University of Cincinnati, Ohio, USA

Summary Several different staircase riser heights and tread depths were investigated in order to determine riser height and tread depth that minimized moments acting at the ankle, knee, and hipjoints while walking upstairs. The results indicated that joint moments were minimized when the riser height was 102mm. For the tread depth, least moments were obtained when the depth was 305mm. Relevance We provide ‘optimum’ staircase riser height and tread depth dimensions joint moments during stair-climbing.

that minimize

Key words: Staircase riser height, Staircase tread depth, Joint moment Introduction In spite of frequent

availahility~ of elevators and escala-

tors in many locations.

indiv,iduals are often forced to

climb stairs. Since the body has to work against gravity. climbing date,

stairs becomes physically very demanding.

only a handful

of scientific

investigations

been reported’-“.

None of these. however.

the determination

of staircase dimensions

To

I,=

0.433

L)

Q=

0.567

L2

Ij=

0.1R L

14= 0.433

L4

15;

L5

0.433

L = Taral

have

HelRhl

dealt with

(riser height

and tread depth). The design of stairways of-thumb.

has generally

Recommendations

depths range between and 356mm.

been by rule-

for stair risers and tread

I02 and 178 mm and between 2X0

respectively”.

These

however,

should be validated

intention

in carrying

out

recommendations,

by research findings. Our

this work

designers with the dimensions

was to provide

that minimize

joint stres-

ses (moments) during stair climbing. Study of lowerlimb mechanics during stair-climbing was not the goal of this work. Figure 1. Schematic of the lower limbs during stair climbing.

Methods Five

healthy

males

and five healthy

females

partici-

pated in our study. Their age ranged between 22 and 36 Suhmirred:I-l

October

19X6 Irr rwr.wd jbrrn:

9

April 1987

C~~rrrspordtwce und reprinr requests 10: Dr A Mital. Research Laboratory. College of Engmeering. nati. Cincinnati. Ohio 45271-0077. USA.

Ergonomics University of Cincin-

years (stature: 79.9 kg). Once

l.S2m-I.75 m; body weight: 49.9 kga person agreed to participate in the

study, dimensions of his/her link segment (Figure lupper body is shown only by one composite segment) were measured. Link segment masses and their centres

Mital

et a/.: Biomechanics

stairs and a picture body weight

of their position.

was balanced

163

of stair climbing

when the entire

on their

right foot (upper

foot) and the left foot (lower foot) was just about to lift off. was taken.

Body joints (ankles.

subject were marked

knees. hip) of the

before taking the pictures.

These

joint markers were digitized with the help of a Summargraphic

HW-2-11

digitizer

and stored

computer. A static two-dimensional determine

in a HP

analysis w’as carried out to

joint moments

since: (i) pilot work revealed

that the average speed of stair climbing (4.02 km/h)

depth

combination

were

calculated.

from

the free

(Figure

the riser heipht-

that yielded

than to determine

ments at each joint.

least moments

the exact magnitude

The

moments

diagram

of mo-

at various

using the equations body

in-

to be very small and (ii) the

purpose of the work was to determine rather

for a subject

remains fairly constant and. therefore.

ertial forces were expected tread

9X30

joints

of equilibrium.

of body

segment

links

2).

Results and Conclusions Figure 2. Free body diagram of the segments.

The

response

data

(joint

moments)

using the analysis of variance. were determined location

from these data’“. The centre of mass

for the upper

from Clauser

et al.”

body segment

was determined

hip-moment, (PSO.01)

analyzed

the exception

of

the effect of riser height was significant

on all moments.

and the interactive

and Havanaa”.

were

With

The effect

effect

tread depth on joint

between

moments

of tread depth

riser

height

were significant

and

at less

The task consisted of subjects climbing nine different types of stairways consisting of three common riser

than 1% level of significance.

heights (102, 1.52 and 203mm)

tests on response means were carried out to determine

depths

(203.

and tread staircase

305 and 406mm).

depth

varied

of climbing

Since the riser height

independently.

it resulted

in

height was I02 mm. Moments

just when their lower leg

point. since the entire body weight is supported

by one

leg on the upper

stair).

of that leg most likely

the stresses on the

are higher

than at any

ally minimized preciable height

fixed on a tripod

and positioned

at the ankle

between

tread

minimize

with respect to stairs was fixed all through

these values also validate

Subjects

were

asked to climb

Table. Summary

of Duncan’s multiple Ankle

Variable Riser height 102 152 203 Tread depth 203 305 406

up each type of

and

vari-

that stairways

with

depth

physical stresses during stair-climbing.

mendations

generally

Knee moment

riser

(0.43).

and response

the rules-of-thumb

followed

bv designers.

range tests on means*

moment

knee

IO).

and 305 mm tread

366m away from the stairs. was used to photograph subjects climbing stairs. The position of the camera the experi-

depth

(PHI.

The results of this study indicate riser height

that the only ap-

that existed were between

and moments

102mm

when riser

at all joints were gener-

analysis indicated

correlations

Correlations

different

when tread depth was 305 mm (Table).

The correlation

ables were insignificant

other point during the climb.

ment.

were

range

that moments at

the ankle and knee joints were minimized

At this

camera.

depths

and

I).

A 35mm

and tread

from each other. The results indicated

The

was about to leave the lower stair (Figure

joints

riser heights

multiple

variable.

a confounded

subjects were photographed

leg (the

which

Duncan’s

sessions was randomized

angle becoming

sequence

and three common tread

Hip moment

(mm) 100~00 120.72 131.76

100-00 120.61 131.68

100~00 97.60 93.03

102.81# 1 oo*oo 104.76#

102.89** 100~00 104.78**

114.52 108.95 100~00

(mm)

*Means are expressed as percentages. Least value is 100% #, **Levels not different from each other (PSO.10) Note: Vertical line indicates the values are not different from each other at the 10% level of significance

should Both recom-

164

Clin. Biomech.

It is important

1987; 2: No 3 that stresses on the joints

mized during climbing,

especially

who are suffering from arthritis,

be mini-

for those individuals

have undergone

recon-

structive surgery in the past or are assisted by artificial limbs/joints. since the joint strength of these individuals is rather low. compared Often,

to normal

individuals.

patients suffer from chronic obstructive

tis and their fatigue)

ability

to sustain physical

is severely

limited.

Reduced

in such cases are extremely

desirable.

Frequently, constraints.

The

data in the Table

If the riser height

approximatelv moments

a 30%

would

203 mm would

suggest that it is

Relaxation

than riser height

is increased

to 152mm.

increase in ankle and knee joint

result.

further

to optimal

in order to meet other design

better to relax tread depth constraint constraint.

(and

physical stresses

it is not possible to conform

design recommendations

hronchi-

exertion

Incrcasc

of

riser

height

increase the moments

of the tread depth constraint.

to

by 10%.

however.

is

not very critical. This study was concerned work is warranted

with stair-climbing:

further

in respect of stair-descent.

Acknowledgement This work was supported Mechanical of Cincinnati. Health

and

and

in part by the Department

Industrial

Engineering.

and the United Human

Scr\,icea

Statc3 Department Grant

no.

of

Universit!. I-ROI-OH-

OlYS6-01 and 03.

References 1 Mu!bridge E. The hum;~n ligurc 111motion. Noi Dover. I SS7

j’ork:

ot

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