Advances in Physical Education 7
2011. Vol.1, No.2, 7-10
Copyright © 2011 SciRes. DOI:10.4236/ape.2011.12002
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.
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
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-
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.
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.
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.
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-
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
NoteOSFS: 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.
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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