Examination of the Usefulness of the Obstacle-Single Leg forward Step (OSFS) Test for Evaluating Fall Risk

doi:10.4236/ape.2011.12002

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Advances in Physical Education 7

2011. Vol.1, No.2, 7-10

Examination of the Usefulness of the Obstacle-Single Leg

Forward Step (OSFS) Test for Evaluating Fall Risk

Sohee Shin1, Shinichi Demura2, Toshiro Sato3

1Center for Innovation Venture Business Laboratory, Kanazawa University, Kanazawa, Japan;

2Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan;

3 Department of Health and Sports, Health and Welfare, Niigata University, Niigata, Japan.

Email: [email protected]

Received October 12th, 2011; revised November 15th, 2011; accepted November 24th, 2011.

This study aimed to examine the usefulness of the Obstacle-Single leg forward step (OSFS) test for evaluating

fall risk and fall-related physical fitness. One hundred and eighty four older women were divided into fallers (n

= 47) who had a fall experience within the last year and non-fallers who had not (n = 137). In the OSFS test,

they stepped forward over an obstacle and returned to their original position five times as quickly as possible.

The OSFS test was also examined in the following divided phases: the OSFS-F phase in which participants

stepped out and the OSFS-R phase in which they returned to the stepped leg. A mean time of five steps was used

for analysis. In addition, the 10-meter walk and one leg standing with open eyes tests were conducted and the

better times were used for analysis. The times of the non-fallers were shorter in the OSFS test, 10-meter walk

time, and were longer in the one-leg standing time than those of the fallers (p-value: OSFS 0.025, 10-meter

0.046, One-leg standing time 0.028). A significant difference was found only in the OSFS-R, the non-fallers

showed shorter time than the fallers (p-value: OSFS-F 0.354, OSFS-R 0.010). The OSFS test can discriminate

the difference between fallers and non-fallers with the same accuracy as the 10-meter walk time and one-leg

standing time tests.

Keywords: The Elderly, Faller/Non-Faller, Fall

Introduction

Falls in the elderly generally result in more serious injury.

Some studies reported that falls frequently occur when turning

around during walking, when initiating walking (Mano, 2008),

or when tripping or stumbling over something. When people

feel that they are falling, they generally try to regain their bal-

ance with a step reset (taking a step) or a jump reset (Hosoda,

2001). However, the elderly, as opposed to the young, often fall

because of delayed response time (Tanaka et al., 2001).

A decline in physical fitness with age is a limiting factor in

successful completion of activities of daily living, and it also

enhances the possibility of falls among elderly people. In order

to adequately evaluate the physical fitness level of the elderly,

it will be important that they complete the requirements of daily

life independently without a fall. Suzuki et al. evaluated the

ADL ability and physical functions of community-dwelling

elderly using the Tokyo Metropolitan Institute of Gerontology

Index, and they reported that the fallers’ score was higher than

that of the non-fallers (Suzuki, 2003; Suzuki, 2000). Tinetti

(1986) also reported that elderly people with a high activity

level have a lower incidence of falls. Hence, a decline in the

ability to perform activities of daily living may closely corre-

spond to the fall risk (Tinetti, 1986).

Until now, some studies on fall prediction have been per-

formed using responses to stepping out against various distur-

bance condtions (Rogers et al., 2001; Hsiao-Wecksler, 2007;

Whitney et al., 2007). Because these studies impose disturbance

stimulations directly on the bodies of the elderly, they may

indeed indicate a fall risk.

Humans avoid a fall and return to a stable base of support

(BOS) by stepping forward quickly when sensing an impending

fall. Shin and Demura (2007, 2009a, 2009b, 2010) focused on

this quick forward step by developing the Single leg forward

step test (SFS test) which evaluates the usefulness of the eld-

erly’s fall-related physical fitness. Because, in the single-leg

forward step test, participants must step forward and then return

to their original position quickly, considerable strength and

balance are both required in the supporting and stepping legs. It

was reported that the test using this movement mirrors the fall

risk score (Demura et al., 2010) and is useful for evaluating the

elderly’s fall-related physical fitness (Shin & Demura, 2010).

Factors associated with falls are divided into two categories -

the inner factor caused by the intrinsic body and the extrinsic

factor caused by a person’s environment. These factors relate

singly or multiply to falls. Although incidents of falls included

“Slipping”, “Reel”, “Missing a step”, “Trip over”, etc., the

main cause of falls among the elderly was tripping over an

obstacle or a step (Saito & Muraki, 2010).

Vandervoot et al. (1989) reported that the elderly experience

falls more often because a sensory and motor function related to

postural and balancing maintenance during walking decreases

with age. Mano (2008) reported that the elderly are inferior in

standing and walking abilities to young people and the decline

in these abilities relates closely to the fall risk. A decline in

physical functions and walking ability with age has been con-

sidered to be the primary cause (Aoyagi, 2001). As suggested

by the above findings, it may be effective to add an obstacle to

the traditional Single leg Forward step test to evaluate the eld-

erly’s fall risk when there is the possibility of a trip.

Meanwhile, the balance and walking abilities of the elderly

have been evaluated by respective one-leg standing time with

open eyes and walking velocity tests (Mano, 2008). A decline

in both abilities corresponded closely with fall risk and is re-

lated to a decline in sensory and motor functions as well as a

change in sensorymotor processing in the central nervous sys-

S. SHIN ET AL.

tem as people age. We hypothesized that the fallers are inferior

to the non-fallers in the Obstacle-Single leg forward step

(OSFS) test.

This study aimed to examine the usefulness of the OSFS test

to evaluate fall risk and the fall-related physical fitness of the

elderly by comparing results on the 10-meter walk test and

one-leg standing with open eyes test.

Methods

Participants

The participants were 184 healthy elderly women who can

walk independently. Prior to various measurements, the pur-

pose and procedure of this study were explained in detail and

informed consent was obtained from all participants. This study

was approved by the Kanazawa University Department of

Education Ethical Review Board.

Participants were divided into fallers (n = 47) with a fall ex-

perience over the last year and non-fallers (n = 137). Table 1

shows their anthropometric characteristics.

Apparatuses and Methods

Obstacle-Single Leg Forward Step Test (OSFS Test)

Participants stood with relaxed arms and barefooted on a step

sheet in a quiet room. They were asked to gaze at an obstacle.

Before the measurement, participants were evaluated to deter-

mine which leg was easiest to stand on and operate by De-

mura’s assessment (Demura et al., 2010). Participants stood

with the supporting leg, stepped forward over the obstacle with

another leg, and returned to an original position five times as

quickly as possible (Figure 1). The step width from the start

spot was 25 cm, and the obstacle was set in the center of the

distance. The obstacle was 10 centimeters high block. The

measurement was conducted in one trial after one practice, and

the mean time of five steps was used for statistical analysis. A

tester controlled an obstacle lightly so that it did not move from

a set place and or fall down even if participants tripped over it.

The step test was performed using the step sheet (Takei inc.

Japan). This device can measure swing time from one leg rising

to landing based on foot pressure information. Parameters were

the time of a forwarding phase (OSFS-F: A mean time of step-

ping forward) and a returning phase (OSFS-R: A mean time of

returning to the original place), and a mean time of both phases.

One Leg Standing Time Test

Participants stood with bare feet and put both hands on their

waist. After lifting up one leg according to a signal, a standing

time was measured. The test was performed using one trial with

each leg. The maximum length of the test was 120 seconds. A

longer time of both legs was used for analysis. In addition, the

time was measured until one of the following occurred: the

lifting foot reached the floor or touched the other leg, the sup-

porting leg’s position shifted, or the lumbar hand left the waist.

10-Meter Walk Test

A 10-meter walk test was conducted on flat ground. A line of

10 cm width was drawn at the start and finish spots so that par-

ticipants knew the course of the walk. Participants were in-

structed to walk as quickly as possible. Using a stopwatch, the

tester measured the time between stepping from the starting line

(0 m) to stepping over the goal line (10 m). A test was conducted

twice and the faster time was used as a representative value.

Data Analysis

Mean differences between the fallers and non-fallers groups

Table 1.

Mean differences of physique characteristics between fallers (n = 137)

and non-fallers (n = 47).

Group Mean SD t-value ES

Age Faller 76.68 5.43 0.906 0.15

(year) Non-faller 75.80 5.89

Height Faller 147.55 4.86 0.448 0.07

(cm) Non-faller147.13 5.98

Weight Faller 50.81 8.45 1.069 0.18

(kg) Non-faller49.37 7.81

Note: ES: Effect size.

Figure 1.

Obstac le Si ngl e leg F orw ard Ste p test (OSFS) test. (a) Participants stepped

forward while stepping over an obstacle (OSFS-F); (b) and returned to

original place while stepping over an obstacle (OSFS-R). Note: Partici-

pants repeated the above measurement five times, as fast as possible.

for each selected parameter were tested using an unpaired t-test.

To examine the size of mean differences, an effect size (ES)

was calculated. The statistical significance level in this study

was set at 5%. Statistical program for the calculation was ap-

plied IBM SPSS statistics 19.

Results

Table 1 shows the test results of the mean differences of

physique characteristics between fallers and non-fallers. There

was no significant difference in age, height and weight between

both groups.

Table 2 shows the test results of mean differences between

groups (fallers/non-fallers) in each test. The times of the

non-fallers were shorter in the OSFS test, 10-meter walk time,

and were longer in the one-leg standing time than those of the

fallers. A significant difference was found only in the OSFS-R

(See 2 and 3 in the method), and the non-fallers had shorter

times than did the fallers. In addition, the effect sizes of the

OSFS and OSFS-R were more than 0.40.

Discussion

To evaluate physical fitness of the elderly, highly safe tests

should be selected due to the elderly’s inferior physical fitness.

In addition, it is desirable that the test content relates closely to

their activities of daily living and is available for rehabilitation

and functional recovery (Demura et al., 2008). This study ex-

amined the usefulness of a new step test which added an Obsta-

cle to the traditional Single leg Forward step test with before

and back shift of a body center of gravity to more adequately

evaluate the elderly’s fall-related physical fitness. This test is

practical because it does not require a large place and also su-

S. SHIN ET AL. 9

Table 2.

Mean differences between Fallers (n = 47) a nd No n-fallers (n = 137) in each test.

Group Mean SD t-value ES

Faller 0.64 0.16

OSFS (sec.) Non-faller 0.59 0.13 2.254 0.40

Faller 0.60 0.16

OSFS-F (sec.) Non-faller 0.58 0.15 0.929 0.16

Faller 0.67 0.18

OSFS-R (sec.) Non-faller 0.60 0.15 2.596 0.46

Faller 6.93 1.24

10-meter walk

time (sec.) Non-faller 6.48 1.31 2.013 0.35

Faller 20.37 28.18

One leg standing

time with eye open

(sec.) Non-faller 32.77 34.68 2.213 0.35

Note―OSFS: Obstacle Single leg Forward Step; ES: Effect size; OSFS(F): Forward phase; OSFS(R): Returning phase.

perior in safety because it involves simple movement that even

the elderly can understand easily.

Fallers were inferior in the OSFS (Obstacle single leg for-

ward step) test to non-fallers. The 10-meter walk time and

one-leg standing time with eyes open also showed similar re-

sults. Mano reported the following: a cause of walking speed

decline depends on shortening of a stride length and a decrease

of pace, and the former attributes this to slight bending of the

knees, a small flexion angle of hip joints, and a small dorsi-

flexion angle of ankles when heels contact the ground. It is a

so-called “shuffle” (a senile walk) (Mano, 2008). Both single

and double stance phases become longer, and kicking out pow-

er also decreases with a leg strength decrease. According to

physiological studies (Vandervoot and Hays, 1989; Era and

Heikkinen, 1985; Gottasdanker, 1982), a cause of falls among

the elderly is a decrease in consciousness-motor system func-

tion which contributes to posture and balance maintenance

during walking in old age. Hence, a decline in physical fitness

factors such as walk ability, balance ability etc. is also consid-

ered to be important in screening the elderly’s fall risk.

The OSFS test as well as the 10-meter walk and one-leg

standing time tests showed that the fallers are inferior to the

non-fallers. In this connection, the former effect size was equal

or somewhat larger than the two later ones. The OSFS test was

constructed by considering the following four standpoints; 1.

When almost falling, the elderly step forward to one step to

keep their base of support (BOS) and prevent fall. 2. A decrease

in leg strength and balance ability as well as the range of mo-

tion (ROM) of the hip, knee and ankle joints are connected with

factors related to fall. 3. The elderly fall frequently by tripping

over an obstacle or a step. 4. The test for screening should use

movements which the elderly can easily understand. Because

the OSFS test demands that the elderly step over the obstacle

while supporting the body with one leg and then return to the

stepped leg’s original position again, it may be difficult for

them with decreased physical fitness as compared with the

movements of walking and one-leg standing.

A significant difference was found in the OSFS-R between

fallers and non-fallers but not in the OSFS-F. Therefore, a fall

risk may be better explained by the movement (OSFS-R) in

returning the stepped leg to the original place than the move-

ment in stepping over an obstacle (OSFS-F). Because of de-

creased leg strength or the fear that one may fall forward, the

elderly cannot stretch their legs sufficiently when their body is

inclined forward (Ryushi, 2008). The movement that is required

when the elderly step forward and return to an original position

again exerts more force on the supporting leg in addition to

maintaining balance. Hence, the elderly with decreased leg

strength, balance ability, and ROM of leg joints may difficulty

in achieving it successfully.

Mano (2008) reported that the elderly’s shuffle contributes to

maintaining balance during walking because a single-leg sup-

port time becomes shorter according to posture changes, and

instability during direction change with age is due to a decline

in sensory function and a delay in central response time. As

confirmed in the movement used in this study and the previous

study, the elderly’s shuffle or senile walk may be a compensa-

tory locomotor way to transfer to the next movement smoothly.

Conclusions

In conclusion, the OSFS test can discriminate between the

fallers and non-fallers as well as 10meter walk time and one-leg

standing time tests. Hence, it may be effective to evaluate the

elderly’s fall-related physical fitness. Additionally, the OSFS-R

may be a better evaluation tool than the OSFS-F.

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