Content uploaded by Michael E. Rogers
Author content
All content in this area was uploaded by Michael E. Rogers on Feb 16, 2017
Content may be subject to copyright.
2121
International Journal of Sport and Health Science Vol.14, 21-30, 2016
http://taiiku-gakkai.or.jp/
Int. J. Sport Health Sci.
Paper : Physiology
EŠects of Body-weight Squat Training on Muscular
Size, Strength and Balance Ability in Physically Frail
Older Adults
Eiji Fujita
1
, Nobuo Takeshima
1
, Yoshiji Kato
2
,DaisukeKoizumi
2
, Makoto Narita
2
,
Hiroki Nakamoto
3
and Michael E. Rogers
4
1
Department of Sport and Life Science, National Institute of Fitness and Sports in Kanoya
1 Shiromizu, Kanoya, Kagoshima 891-2393 JAPAN
E-mail: takeshima
@
nifs-k.ac.jp
2
Active Aging Association
2-92 Namiuchi-cho, Kita-ku, Nagoya, Aichi 462-0041 JAPAN
3
Department of Sports Humanities and Applied Social Science, National Institute of Fitness and Sports in Kanoya
1 Shiromizu, Kanoya, Kagoshima 891-2393 JAPAN
4
Department of Human Performance Studies, Center for Physical Activity and Aging, Wichita State University
106G Heskett Center, 1845 Fairmount St., Wichita, Kansas 67260-0016 USA
[Received January 13, 2015; Accepted March 4, 2016; Published online May 31, 2016]
The purpose of this study was to evaluate the eŠects of a 12-week group-based body-weight
squat training program on muscle mass, muscle strength, and balance in physically frail com-
munity-dwelling older men and women. Fifteen older adults (mean age
=
78.7 yr) who needed
assistance performing activities of daily living (ADL) according to long-term care insurance
regulations in Japan participated in the study. Participants performed squat exercise in a group-
setting using body-weight as resistance while singing for one set consisting of 48 reps twice
weekly for 12 weeks. Body mass, thigh girth, thigh muscle thickness assessed by B-mode
ultrasound, knee extension torque (KET), static and dynamic balance (static (SB): sway velocity
(SV) standing on ˆrm or foam surfaces with eyes open or closed; dynamic (DB): limits of stabil-
ity) were measured before and after the intervention. Following the intervention, participants
signiˆcantly (
P
<
0.05) decreased body mass and increased KET relative to body mass. Although
thigh girth did not change, thigh muscle thickness did increase. There were no appreciable
changes in DB nor in SB, except SV standing on a ˆrm surface with the eyes open improved.
Group-based body-weight squat exercise in physically frail older adults improves muscle mass
and strength but has little eŠect on balance parameters.
Keywords: Body-weight squat training, speciˆcity of exercise, frail older adults
1. Introduction
With a rapidly growing older population, loss of
independence has become a serious problem in
Japan as well as around the world. This has led to a
growing number of adults requiring long-term care
that imposes medical expenses and social burdens.
One quality for successful aging is the ability to
independently perform activities of daily living
(ADL) such as standing from a seated position,
walking, and climbing stairs (Hazell, et al., 2007).
Because muscle weakness and poor balance are asso-
ciated with an increased risk of disability (Guralnik
et al., 1995) and falls (Tinetti et al., 1986), many ex-
ercise programs have been developed to improve
these capacities in older adults (Chang et al., 2004;
Faberetal.,2006;Haueretal.,2003;Islametal.,
2004). Additionally, several studies have shown that
resistance exercise, particularly machine-based
exercise and/or using dumbbells or free weights, is
beneˆcial for frail older adults as well as healthy
older adults (Fiatarone, et al., 1994; Mihalko and
McAuley, 1996). However, it is typically not feasible
to have large, expensive training equipment in day
service centers that provide care for older adults.
Previous research has shown that training with
2222
Int. J. Sport Health Sci.
ankle-weight cuŠs and resistance bands, or using
participants' body weight as resistance, to be eŠec-
tive but no details were provided regarding the exer-
cise intensity used in these interventions (Yamauchi
et al., 2005; Rosie and Taylor, 2007; Shaw and
Snow, 1998; Takeshima et al., 2013; Yoshitake et
al., 2011).
Recently, we reported that the activity level of the
quadriceps femoris during a body mass-based squat
movement is in‰uenced by its force generation
capability (Fujita et al., 2011). For individuals with
a knee extension torque (KET) relative to body
mass less than 1.9 Nm/kg
-
1
, body mass-based squat
movement is considered to be a fairly high-intensity
activity. The breakpoint of 1.9 Nm/kg
-
1
may be
assumed to be a threshold level of knee extensor
strength, which should be maintained to perform
ADL without great di‹culty. Although, body mass-
based squat movement seems of adequate exercise
intensity for frail older adults, little is known about
the eŠects of long-term training using this activity.
Age-related loss in knee extensor strength in-
creases the di‹culty of performing ADL, such as
walking, rising, and stepping (Hortob áagyi et al.,
2003) and the risks of falling and associated fracture
(Wolfson et al., 1995; Kirkendall and Garrett,
1998). Moreover, a sit-to-stand movement like
squatting requires greater muscle strength than other
daily activities, such as walking or stair climbing
(Ploutz-Snyder et al., 2002; Yoshioka et al., 2007).
Therefore, the development of an eŠective interven-
tion that targets the knee extensors would be of
beneˆt to frail older adults.
Despite the known beneˆts of exercise in main-
taining independence, participation rates are not
high among all age groups (Ashworth et al., 2005).
Previous studies have used home-based exercise pro-
grams that can be less costly and do not require par-
ticipant transportation but program adherence and
appropriate exercise progression can be problematic
(Olson et al., 2011). Older adults value the sense of
fulˆllment provided by the social interactions with
the other participants, as well as the support and
encouragement received from the group (Dionigi,
2007; Layne et al., 2008). In addition, the social sup-
port given in group-based programs can counteract
the isolation that older adults often experience, and
companionship during activities improves physical
activity among older adults (Layne et al., 2008;
Shores et al., 2009). Furthermore, those who re-
ported high enjoyment in physical activity were
more likely to report higher levels of activity
(Salmon et al., 2003).
The purpose of this study was to evaluate changes
in muscle strength, muscle mass, and balance in
physically frail community-dwelling older men and
women following a 12-week group-based exercise
program consisting of squat exercise using partici-
pants' body weight as resistance while singing
together.
2. Methods
2.1. Participants and exercise program
Fifteen older adults (6 males and 9 females) who
needed assistance performing ADL according to
long-term care insurance regulations in Japan par-
ticipated in the study. The means and standard devi-
ations (SDs) of age, height, and body mass for the
participants were 78.7
±
4.1 years, 151.5
±
8.7 cm,
57.4
±
11.4 kg, respectively. Height was measured
using a digital stadiometer (DSN-90, Muratec-KDS,
Kyoto, Japan) to the nearest 0.1 cm. Body weight
wasmeasuredtothenearest0.1kgusingadigital
scale (HBF-214, Omron, Tokyo, Japan). Table 1
shows nursing care levels and presence of diseases at
pre-testing.
The ethical committee of the National Institute of
Fitness and Sports in Kanoya approved the study.
All participants received written and oral instruc-
tions for the study and each gave their written in-
formed consent prior to participation.
All participants performed the squat exercise us-
ing body-weight as resistance for one set of 48 reps
while singing together on 2 days per week for 12
weeks. Starting in the seated position, participants
completed 48 reps by continuously standing from
and sitting in a standard chair (seat height 43 cm)
(Figure 1). Each full repetition took approximately
4 sec with the entire set being completed in approxi-
mately 3.5 min. Based on the work of Fukunaga
(2006), participants sang traditional songs while per-
forming the exercise. The goal of this was to prevent
the Valsalva maneuver and to create an atmosphere
of happiness.
2.2. Testing
Measurements included body mass, thigh girth,
23
Table 1 Characteristics of Participants
Participants Sex Nursing
care level pressure of disease
A m S1 asthma, osteoporosis
B m S2 lumbar canal stenosis
C m L1 parkinson disease
D m S1 hypothyroidism, lumbar spondylosis
E m L2 brain infaction (right hemiplegia), angina pectoris, cervical spondylotic myelopathy
F m L1 diabetes, hypertension, kidney disease (requiring dialysis)
G f S2 diabetes, angina pectoris, ossiˆcation of the posterior longitudinal ligament
H f L1 lumbar spondylolisthesis
I f S2 parkinson disease, diabetes, osteoporosis
J f S2 femoral neck fracture (femoral head replacement), diabetes, hypertension
K f S1 parkinson disease
L f L1 brain infaction (left hemiplegia), lung cancer
M f S1 lumbar spondylosis, knee osteoarthritis
N f S1 diabetes (retinopathy and peripheral neuropathy), cerebral infarction sequelae
O f S2 diabetes, hypertension, epilepsy, thoracic compression fracture, cerebral infarction sequelae
Note: m: male, f: female, S: support required level 1 and 2 (Those who need no continuous care but need some support in daily life
such as help with dressing themselves), L: long-term care required for their daily living level 1-5 (Those who need continuous
care because of being bedridden, dementia, etc.)
Figure 1. Body-weight squat exercise
Body-weight-squat exercise using a standard chair (seat height 43 cm).
23
Body-weight squat in frail older adults
anterior thigh muscle thickness, isometric maximal
knee extension torque, and static and dynamic
balance (static (SB): sway velocity (SV) standing on
ˆrm or foam surfaces with eyes open or closed;
dynamic (DB): limits of stability). These measure-
ments were conducted before and after the 12-week
intervention. Throughout the study, the same tech-
nician conducted all data collection and analysis.
2.3. Method for measurement
2.3.1. KET
KET during isometric maximal voluntary contrac-
tion (MVC) was measured using a specially designed
dynamometer (Takei, Niigata, Japan) with tension /
compression load cells (LUR-A-SAI, Kyowa,
Tokyo, Japan). The right leg was measured for all
participants. The participants sat on the dynamome-
ter at 90 degrees of hip and knee joint ‰exion (full
extension
=
0 degree). The participant's hip was ˆx-
ed by a non-elastic belt to prevent postural change.
Torque data from each trial were ampliˆed using a
strain ampliˆer (DPM-751A, Kyowa, Tokyo,
Japan). The torque signals obtained via a 16-bit ana-
log / digital converter (PowerLab/16s, AD Instru-
ments, Sydney, Australia) were recorded on a per-
sonal computer at a sampling frequency of 1 KHz.
Participants gradually exerted muscle force from
rest to maximum over 5 sec and then sustained max-
imal exertion for approximately 2 sec. Before the
maximal testing, participants were asked to exert
submaximal muscle force to become familiar with
the test procedure. Participants performed 2 trials
with a 3-min rest between trials to exclude the in-
‰uence of fatigue. The highest value among the tri-
als was used for analysis. The KET was expressed
relative to body mass (KET/BM). This procedure
has been described by Fujita et al. (2011) and
24
Figure 2. Thigh muscle thickness assessed by B-mode ultrasound
Muscle thickness of the anterior thigh was measured as the distance between the fat-muscle tissue and muscle-bone
interface by a B-mode ultrasound with a 6 MHz linear scanner.
24
Eiji Fujita, et al.
Yoshitake et al. (2011).
2.3.2. Muscle thickness (MT)
MT of the anterior thigh was measured as the dis-
tance between the fat-muscle tissue and muscle-bone
interface by a B-mode ultrasound (Mirucube,
Global health, Kanagawa, Japan) with a linear scan-
ner. The right leg was measured for all participants.
During ultrasound measurements, participants
remained in a standing position with their legs and
arms straight and muscles relaxed as described previ-
ously (Ishida et al., 1995). The anthropometric loca-
tion of the measurement site was precisely located
and marked on the anterior surface at the midline of
the femoral length (the distance from the greater
trochanter of the femur to articular cleft between the
femur and tibial condyles). A transducer with a
6MHz scanning head was placed perpendicular to
the underlying muscle and bone tissues. The scan-
ning head was coated with ultrasonic gel, which
provided acoustic contact without depressing the
dermal surface. The ultrasonographic images were
analyzed by dedicated analytical software (Mirucube
Yver.1.0,Globalhealth,Kanagawa,Japan).MT
was measured to the nearest 0.1 mm. One examiner
performed the muscle thickness measurements
throughout this study (Figure 2). The measurements
were taken with a vernier caliper to the nearest 0.1
mm. The intraclass correlation coe‹cients for the
tissue thickness measurements on two diŠerent days
were 0.99 to1.00 for MT (Takeshima et al., 2014).
The accuracy and test-retest repeatability of the
muscle thickness measurements have also been
established in prior studies (Miyatani et al., 2003;
Sanada, et al., 2006).
2.3.3. Static (SB) and dynamic (DB) balance tests
A Balance Master Platform System (NeuroCom
International, Oregon, USA) was used to measure
SB and DB (Rogers et al., 2003). SB measures were
taken while standing on diŠerent surfaces with the
eyes open or closed, and on diŠerent of surface con-
ditions (ˆrm or with foam pad). In this study, the
Clinical Test of Sensory Interaction for Balance us-
ing the Balance Master Platform System was used as
a test of postural SV that was designed to measure
the in‰uence of sensory input on balance (Nashner
and McCollum, 1985). Composite SV (SVcomp)
scores were calculated based on each sway velocity
condition as an index of SB. The test required the
participant to stand: (a) on a ‰at surface with the
eyes open (SVcomp1); (b) on a ‰at surface with the
eyes closed (SVcomp2); (c) on thick foam with the
eyes open (SVcomp3); and (d) on thick foam with
the eyes closed (SVcomp4). The force platform was
marked to maintain consistency in foot placement.
For each stance, the participant stood with their eyes
at the horizon and their arms at the sides in a neutral
position. Trials required 10 sec of data collection
(Figure 3-a).
DB was determined using the limits of stability
(LOS) assessment in which 8 targets appeared
around a center square at 0 (forward), 45, 90 (right),
135, 180 (back), 225, 270 (left), and 315 degrees
(Figure 3-b). Center of pressure (COP) appeared on
a monitor as a human-shaped cursor and moved as
participants shifted their weight toward an identiˆed
target, holding the position for 5 sec. Each LOS trial
measured endpoint (EPE) and maximum excursion
(MXE). EPE ends when the COP movement ˆrst
ceases progression toward the target. EPE was ex-
25
Figure 3. Static and dynamic balance tests with the Balance Master Platform System
Static balance was quantiˆed using postural sway velocity while standing on diŠerent surfaces (ˆrm or with foam
pad) with the eyes open or closed (a). Dynamic balance was determined using the limits of stability assessment in 8
directions located around a center target as the starting point at 0 (forward), 45, 90 (right), 135, 180 (back), 225,
270 (left), and 315 degrees (b).
25
Body-weight squat in frail older adults
pressed as a percentage of the distance to the target.
Hence, a participant whose initial movement ends
precisely at the target had an EPE of 100
z
.When
initial attempts were substantially short of the tar-
get, most people initiated additional movements af-
ter the EPE was recorded. To represent this addi-
tional movement and COP excursion, an additional
measurement, the MXE was used. The MXE was the
maximum distance the COP was displaced toward
the target over the entire duration of the trial
(Rogers, et al., 2003). MXE was also expressed as a
percentage of the distance to the target. Four direc-
tions (forward, back, right and left) and composite
EPE and MXE scores were calculated based on
movements toward all 8 targets. These scores of
reaction time (RT), movement velocity (MVL), and
directional control (DC) were also used. RT was
time in seconds between the signal to move and the
initiation of movement. MVL was body tilt velocity
and calculated based on the average speed of COP
movement between 5
z
and 95
z
of the distance to
the primary endpoint using one's height as a refer-
ence and expressed in degrees per sec. Directional
control, expressed as percent, was based on 100
z
being a straight line from the initial center of pres-
sure to the intended target. Because the participants
were asked to move quickly, rapid reaction time and
greater speed was desirable, but participants must
also have been able to control the movement in the
intended direction.
The SB and DB tests were administered in a single
testing session on the same days. A 3-minute rest in-
terval was provided between each test. Following
verbal instruction and demonstration by the tester,
participants completed one practice trial and one
test trial while barefoot. There were no unsuccessful
trials for these tests.
2.4. Statistical analysis
Descriptive data are expressed as means and stan-
dard deviations (SDs). Pre- and post-test compari-
sons were performed using dependent t-tests. EŠect
size [ES] was also calculated for each test. Cohen's
deˆnition of small, medium and large ESs (ES
=
0.2,
0.5, and 0.8, respectively) was used (Cohen, 1988).
A probability value of less than 0.05 was considered
statistically signiˆcant. All data were analyzed using
26
Table 2 Body mass, thigh girth, muscle thickness, and
strength at pre- and post- assessment
Measurements Pre- Post- p-value ES
Body mass (kg) 57.4
±
11.4 56.5
±
11.1 0.036*0.53
Thigh girth (cm) 44.6
±
4.3 44.4
±
4.1 0.328 (n.s.) 0.26
MT (mm) 29.2
±
5.8 31.0
±
5.4 0.007** 0.65
KET (Nm) 67.3
±
21.1 73.9
±
24.0 0.010** 0.63
KET/BM (Nm/kg) 1.19
±
0.34 1.32
±
0.4 0.003** 0.69
Note: MT: muscle thickness, KET: knee extension torque,
KET/BM: KET relative to body mass, **:
P
<
0.01, *:
P
<
0.05, n.s.: not signiˆcant
Table 3 Static balance at pre- and post- assessment
Measurements Pre- Post- p-value ES
EO-Firm (deg/sec) 0.41
±
0.26 0.31
±
0.13 0.042*0.51
EC-Firm (deg/sec) 0.57
±
0.22 0.57
±
0.23 0.705 (n.s.) 0.10
EO-Foam (deg/sec) 1.24
±
0.79 1.03
±
0.40 0.129 (n.s.) 0.41
EC-Foam (deg/sec) 3.94
±
1.90 3.96
±
1.57 0.969 (n.s.) 0.11
Note: EO: eyes open, EC: eyes closed, Firm: ˆrm surface,
Foam: foam surface, *:
P
<
0.05, n.s.: not signiˆcant
26
Eiji Fujita, et al.
SPSS ver. 15.0 for Windows statistical software
(SPSS Inc., Tokyo, Japan).
3. Results
All participants continued the current exercise
program with no incidence of injury during the
study and no participant declined to participate in
the intervention. Mean attendance rate for this exer-
cise group was 93.1
z
.
Following the intervention, participants sig-
niˆcantly (
P
<
0.05) decreased body mass by 1.6
z
(57.4
±
11.4 to 56.5
±
11.1 kg, ES
=
0.53), and sig-
niˆcantly increased KET by 9.8
z
(67.3
±
21.1 to
73.9
±
24.0 Nm, ES
=
0.63) and KET/BM by 10.9
z
(1.19
±
0.34 to 1.32
±
0.38 Nm/kg, ES
=
0.69) (Table
2). However, there were no signiˆcant correlation
between KET/BM before the intervention and the
relative changes after the intervention. Apart from
that, thigh girth did not change, thigh muscle thick-
ness signiˆcantly increased by 6.2
z
(29.2
±
5.8 mm
to 31.0
±
5.4 mm). There were no appreciable
changes in DB nor in SB. However, SV standing on
a ˆrm surface with the eyes open improved by
26.2
z
(0.42
±
0.25 to 0.31
±
0.13 mm/sec) (Tables 3
and 4).
4. Discussion
The purpose of the present study was to evaluate
the eŠects of a 12-week group-based body-weight
squat exercise program on muscle mass, muscle
strength, and balance in physically frail community-
dwelling older men and women. The 12-week pro-
gram signiˆcantly decreased body mass by 1.6
z
(ES
=
0.53), increased KET by 9.8
z
(ES
=
0.63), and in-
creased KET/BM by 10.9
z
(ES
=
0.69). Moreover,
although thigh girth did not change, thigh muscle
thickness did increase by 6.2
z
(ES
=
0.65). These
results suggest that performing chair squat using
body-weight as resistanceiseŠectiveinimproving
muscular strength and muscle mass in physically
frail older adults.
A government-supported nursing-care insurance
system exists in Japan that provides inexpensive care
to older adults who utilize the program. Although it
is a good system, it does not entail a component of
physical activity as exercise machines are expensive
and space is limited in day centers and nursing
homes. The results of the present study suggest that
an exercise program consisting of body-weight exer-
cises is eŠective in improving strength and therefore
could be incorporated into this system as it is inex-
pensive and requires only a chair.
Mean attendance rate for the exercise group was
93.1
z
. Previous studies have suggested that 50
z
of
people who begin an exercise program discontinue
within 6 months (Hong et al., 2008; Medina-
Mirapeix et al., 2009; Kallings, et al., 2009). An
adherence level of at least 80
z
to 85
z
is recom-
mended if an intervention is to have a meaningful
eŠect and therapeutic value (Pisters et al., 2010).
Although the present study was only 12 weeks in
duration, it appears that adherence was su‹ciently
high and may be, in part, attributed to the incorpo-
ration of group-based exercise that incorporated
singing. Further study is needed to assess the psy-
chological parameters that contribute to the high
attendance associated with this program.
In general, the relative improvement ratio from
training can be considered to have greater impact on
muscle in participants with low ˆtness levels, such as
those in this study, as they are starting at a func-
tional level at which they have di‹culty performing
activities of daily living. In addition, Fujita et al.
(2011) reported that the activity level of the quad-
riceps femoris during body-weight-based squat
27
Table 4 Dynamic balance at pre- and post- assessment
Measurements Pre- Post- p-value ES
RT (sec)
Forward 1.22
±
0.42 0.95
±
0.27 0.058 (n.s.) 0.48
Back 0.95
±
0.40 0.87
±
0.25 0.205 (n.s.) 0.34
Right 1.08
±
0.41 0.95
±
0.34 0.232 (n.s.) 0.06
Left 1.04
±
0.50 0.92
±
0.29 0.447 (n.s.) 0.21
Comp 1.07
±
0.37 0.92
±
0.24 0.118 (n.s.) 0.41
MVL (deg/sec)
Forward 2.06
±
0.69 2.16
±
0.74 0.655 (n.s.) 0.12
Back 1.43
±
0.70 1.87
±
0.75 0.036*0.53
Right 3.11
±
1.28 3.91
±
2.06 0.200 (n.s.) 0.05
Left 2.91
±
1.46 3.17
±
1.01 0.551 (n.s.) 0.16
Comp 2.39
±
0.91 2.78
±
0.96 0.236 (n.s.) 0.31
EPE (
z
)
Forward 44.13
±
15.84 45.67
±
11.39 0.651 (n.s.) 0.12
Back 37.40
±
16.75 39.93
±
16.51 0.522 (n.s.) 0.17
Right 64.53
±
19.31 77.73
±
20.56 0.039*0.52
Left 62.87
±
19.24 71.47
±
18.99 0.186 (n.s.) 0.35
Comp 52.33
±
14.20 59.00
±
11.97 0.073 (n.s.) 0.46
MXE (
z
)
Forward 60.60
±
14.62 60.87
±
16.51 0.929 (n.s.) 0.24
Back 49.00
±
20.54 54.93
±
19.28 0.206 (n.s.) 0.34
Right 84.67
±
17.12 96.13
±
17.92 0.022*0.57
Left 81.00
±
20.48 86.93
±
18.53 0.297 (n.s.) 0.28
Comp 68.87
±
15.13 74.87
±
12.94 0.065 (n.s.) 0.47
DCL (
z
)
Forward 77.73
±
9.68 71.60
±
13.72 0.094 (n.s.) 0.43
Back 59.20
±
23.45 63.73
±
18.37 0.063 (n.s.) 0.48
Right 74.27
±
11.40 74.80
±
8.16 0.784 (n.s.) 0.08
Left 70.60
±
14.78 72.00
±
10.41 0.707 (n.s.) 0.10
Comp 70.60
±
12.84 70.60
±
9.18 1.000 (n.s.) 0.00
Note: RT: reaction time, MVL: movement velocity, EPE: endpoint excursion, MXE: maximum excur-
sion, DCL: directional control, Comp: composite value, *:
P
<
0.05, n.s.: not signiˆcant
27
Body-weight squat in frail older adults
movement is in‰uenced by the force generation
capability during the squat movement. For individu-
als with a KET/BM less than 1.9 Nm/kg, body-
weight-based squat movement is considered to be a
high-intensity activity. All of the participants in the
present study were below this threshold both before
and after the intervention suggesting that they were
performing a high-intensity exercise throughout the
intervention.
Yoshitake et al. (2011) have shown that body-
weight-based squat exercise increased KET/BM by
15.0
z
(2.18
±
0.63 to 2.42
±
0.58 Nm/kg) in healthy
middle-aged and older women. In the current study,
the gain in KET/BM was lower (10.9
z
)thanthe
study of Yoshitake et al. (2011). A plausible reason
for that is the frequency of exercise in the current
study was only twice a week while the study of
Yoshitake et al. (2011) utilized a frequency of at
least six days per week. Although Nakamura et al.
(2007) reported that an exercise intervention of only
twice per week was not su‹cient to induce sig-
niˆcant improvements, participants in the current
study did improve functional ˆtness signiˆcantly. It
remains to be determined if performing squat exer-
cises in greater volume (e.g., more sets, greater
training frequency, longer training duration) would
result in additional increases in the outcomes as-
sessed in this study. Further research is needed to
clarify this point.
According to Yoshitake et al. (2011), the eŠect of
training on lower muscle strength using body mass
depends on the baseline value before intervention.
This is because the level of muscle activity in the
quadriceps during the squat movement is inversely
correlated with KET/BM (Takai et al., 2008; Fujita
et al., 2011), so the lower the KET/BM, the higher
the intensity of exercise becomes. The results of the
current study did not show a signiˆcant correlation
between KET/BM before the intervention and the
relative changes after the intervention. One explana-
tion for this may be that the number of subjects in
this study was smaller than that in the previous study
by Yoshitake et al. (2011) and the KET/BW values
were within a narrower range (0.73 to 1.89 Nm/kg)
2828
Eiji Fujita, et al.
than the studies of Takai et al. (2008) and Yoshitake
et al. (2011).
Squat and sit-to-stand movements are accompa-
nied by forward and backward weight shift in the
sagittal plane (Schenkmen et al., 1990). Therefore,
we expected that if squat training were to have an
eŠect on balance that such improvements would
appear in the forward and backward directions.
Although strength improved, there were no appreci-
able changes in DB nor in SB, except SV standing on
a ˆrm surface with the eyes open improved by
26.2
z
. In many cases, falls are caused by a loss of
balance (Nickens, 1985; Tinetti and Speechley,
1989). During both static and dynamic balance,
posture is controlled by the detection of distur-
bances to the center of gravity and the initiation of
appropriate responses to return the body to a stable
position. This is a complex process controlled to a
large extent by the visual, somatosensory, and ves-
tibular systems. In addition, the muscular system
contributes to balance control since all body move-
ments are produced via contraction of skeletal mus-
cles. With increasing age, there is a decrease in sen-
sory function (Wolfson et al., 1992; Era et al., 2006)
and a decrease in muscle strength (Porter et al.,
1995). Slobounov et al. (1998) measured postural
sway in older adults aged 67 to 92 years and found
that postural sway, with eyes open and closed, in-
creased with age, but was aŠected to a much greater
extent when visual cues were removed. Hasan et al.
(1990) investigated changes in postural sway in
women over the age of 65 during eyes open double
stance, eyes open single stance, eyes closed double
stance, and eyes closed single stance. The velocity of
sway increased when the visual cues were removed
and when the feet were positioned to reduce the size
of the base. Therefore, the eŠect of vision on postur-
al sway may become increasingly important with
age. Furthermore, a reduced base of support (e.g.,
when the feet are in the semi-tandem, tandem, or
unilateral positions as occurs during walking) may
increase the risk for suŠering a fall, especially in
dimly illuminated conditions that compromise visual
sensation. Although Takeshima et al. (2013) have
shown that an age-related decline exists for both SB
and DB, we have also shown that customized
balance training can improve dynamic balance
(Narita et al., 2015), so it is possible that the inclu-
sion of some balance training activities with the
squat exercises used in the current study may im-
prove muscle strength, muscle thickness, and
postural balance in frail older adults which could
contribute to the prevention of falls. Many balance
exercises can be performed with only the use of a
chair and could easily be performed in conjunction
with body-weight squats exercises without requiring
additional space or equipment.
A limitation of this study is the lack of a control
group. Although this is appropriate and acceptable
for a quasi-experimental design, a stronger defense
of the intervention would be made with a controlled,
randomized approach.
In conclusion, group-based body-weight squat
exercise performed twice weekly for 12 weeks does
improve muscle strength and muscle thickness in
physically frail older adults. This program is eŠec-
tive, simple and inexpensive, making it suitable for
this population.
Acknowledgments
The authors are grateful to the subjects who participated in
this study.
References
Ashworth,N.L.,Chad,K.E.,Harrison,E.L.,Reeder,B.A.,
and Marshall, S. C. (2005) Home versus center based physical
activity programs in older adults. Cochrane Database Syst.
Rev., CD004017.
Chang, J. T., Morton, S. C., Rubenstein, L. Z., Mojica, W. A.,
Maglione,M.,Suttorp,M.J.,Roth,E.A.,andShekelle,P.
G. (2004). Interventions for the prevention of falls in older
adults: Systematic review and meta-analysis of randomised
clinical trials. BMJ., 328: 680.
Cohen, J. (1988). Statistical power analysis for the behavioral
sciences (2nd ed.). Oxon: Routledge.
Dionigi, R. (2007). Resistance training and older adults' beliefs
about psychological beneˆts: The importance of self-e‹cacy
and social interaction. J. Sport Exerc. Psychol., 29: 723-746.
Era, P. and Heikkinen, E. (1985). Postural sway during stand-
ing and unexpected disturbance of balance in random samples
of men of diŠerent ages. J. Gerontol., 40: 287-295.
Era, P., Sainio, P., Koskinen, S., Haavisto, P., Vaara, M., and
Aromaa, A. (2006). Postural balance in a random sample
of 7,979 subjects aged 30 years and over. Gerontology, 52:
204-213.
Faber, M. J., Bosscher, R. J., Chin, A., Paw, M. J., and van
Wieringen, P. C. (2006). EŠects of exercise programs on falls
and mobility in frail and pre-frail older adults: A multicenter
randomized controlled trial. Arch. Phys. Med. Rehabil., 87:
885-896.
Fiatarone,M.A.,O'Neill,E.F.,Ryan,N.D.,Clements,K.
M., Solares, G. R., Nelson, M. E., Roberts, S. B., Kehayias,
J. J., Lipsitz, L. A., and Evans, W. J. (1994). Exercise train-
ing and nutritional supplementation for physical frailty in
very elderly people. N. Engl. J. Med., 330: 1769-1775.
Fujita, E., Kanehisa, H., Yoshitake, Y., Fukunaga, T., and
Nishizono, H. (2011). Association between knee extensor
2929
Body-weight squat in frail older adults
strength and EMG activities during squat movement. Med.
Sci. Sports. Exerc., 43: 2328-2334.
Fukunaga, T. (2006). [Chokin-manual for exercise instructor].
Tokyo: Hokendohjinsha. (in Japanese)
Guralnik, J. M., Ferrucci, L., Simonsick, E. M., Salive, M. E.,
and Wallace, R. B. (1995). Lower-extremity function in per-
sons over the age of 70 years as a predictor of subsequent
disability. N. Engl. J. Med., 332: 556-561.
Hasan, S. S., Lichtenstein, M. J., and Shiavi, R. G. (1990).
EŠect of loss of balance on biomechanics platform measures
of sway: In‰uence of stance and a method for adjustment. J.
Biomech., 23: 783-789.
Hauer, K., Pˆsterer, M., Schuler, M., B äartsch, P., and Oster,
P. (2003). Two years later: A prospective long-term follow-up
of a training intervention in geriatric patients with a history of
severe falls. Arch. Phys. Med. Rehabil., 84: 1426-1432.
Hazell, T., Kenno, K., and Jakobi, J. (2007). Functional beneˆt
of power training for older adults. J. Aging Phys. Act., 15:
349-359.
Hong, S. Y., Hughes, S., and Prohaska, T. (2008). Factors
aŠecting exercise attendance and completion in sedentary
older adults: A meta-analytic approach. J. Phys. Act. Health,
5: 385-397.
Hortob áagyi, T., Mizelle, C., Beam, S., and DeVita, P. (2003).
Old adults perform activities of daily living near their max-
imal capabilities. J. Gerontol.ABiol.Sci.Med.Sci.,58.,
M453-460.
Ishida, Y., Kanehisa, H., Carroll, J. F., Pollock, M. L.,
Graves, J. E., and Leggett, S. H. (1995). Body fat and muscle
thickness distributions in untrained young females. Med. Sci.
Sports Exerc., 27: 270-274.
Islam, M. M., Nasu, E., Rogers, M. E., Koizumi, D., Rogers,
N. L., and Takeshima, N. (2004). EŠects of sensory and mus-
cular training on balance in Japanese older adults. Prev.
Med., 39: 1148-1155.
Kallings,L.V.,Leijon,M.E.,Kowalski,J.,Helláenius, M. L.,
and St ¹ahle, A. (2009). Self-reported adherence: a method for
evaluating prescribed physical activity in primary health care
patients. J. Phys. Act. Health, 6: 483-492.
Kirkendall, D. T. and Garrett, W. E. Jr. (1998). The eŠects of
aging and training on skeletal muscle. Am. J. Sports Med.,
26: 598-602.
Layne, J. E., Sampson, S. E., Mallio, C. J., Hibberd, P. L.,
Gri‹th, J. L., Das, S. K., Flanagan, W. J., and Castaneda-
Sceppa, C. (2008). Successful dissemination of a community-
based strength training program for older adults by peer and
professional leaders: The people exercising program. J. Am.
Geriatr. Soc., 56: 2323-2329.
Medina-Mirapeix, F., Escolar-Reina, P., Gasco áan-Ca áanovas, J.
J., Montilla-Herrador, J., and Collins, S. M. (2009). Per-
sonal characteristics in‰uencing patients' adherence to home
exercise during chronic pain: A qualitative study. J. Rehabil.
Med., 41: 347-352.
Mihalko, S. L. and McAuley, E. (1996). Strength training
eŠects on subjective well-being and physical function in the
elderly. J. Aging Phys. Act., 4: 56-68.
Miyatani, M., Kanehisa, H., Azuma, K., Kuno, S., and
Fukunaga, T. (2003). Site-related diŠerences in muscle loss
with aging ``A cross-sectional survey on the muscle thickness
in Japanese men aged 20 to 79 years''. Int. J. Sport. Health.
Sci., 1: 34-40.
Nakamura, Y., Tanaka, K., Yabushita, N., Sakai, T., and
Shigematsu, R. (2007). EŠects of exercise frequency on func-
tional ˆtness in older adult women. Arch. Gerontol. Geriatr.,
44: 163-173.
Narita, M., Islam, M. M., Rogers, M. E., Koizumi, D., and
Takeshima, N. (2015). EŠects of customized balance exercises
on older women whose balance ability has deteriorated with
age. J. Women Aging, 27: 237-250.
Nashner, L. M. and McCollum, G. (1985). The organization of
human postural movements: A formal basis and experimental
synthesis. Behav. Brain Sci., 8: 135-150.
Nickens, H. (1985). Intrinsic factors in falling among the
elderly. Arch. Intern. Med., 145: 1089-1093.
Olson, S. L., Chen, S. S., and Wang, C. Y. (2011). EŠect of a
home exercise program on dynamic balance in elderly with a
history of falls. J. Aging Phys. Act., 19: 291-305.
Pisters, M. F., Veenhof, C., Schellevis, F. G., Twisk, J. W.,
Dekker, J., and De Bakker, D. H. (2010). Exercise adherence
improving long term patient outcome in patients with os-
teoarthritis of the hip and/or knee. Arthritis Care Res., 62:
1087-1094.
Ploutz-Snyder, L. L., Manini, T., Ploutz-Snyder R. J., and
Wolf,D.A.(2002).Functionally relevant thresholds of quad-
riceps femoris strength. J. Gerontol. A Biol. Sci. Med. Sci.,
57: B144-152.
Porter, M. M., Vandervoort, A. A., and Lexell, J. (1995).
Aging of human muscle: Structure, function, and adaptabil-
ity. Scand. J. Med. Sci. Sports., 5: 129-142.
Rogers, M. E., Rogers, N. L., Takeshima, N., and Islam, M.
M. (2003). Methods to assess and improve the physical pa-
rameters associated with fall risk in older adults. Prev. Med.,
36: 255-264.
Rosie, J. and Taylor, D. (2007). Sit-to-stand as home exercise
for mobility-limited adults over 80 years of age-GrandStand
System
TM
may keep you standing? Age Aging, 36: 555-562.
Salmon, J., Owen, N., Crawford, D., Bauman, A., and Sallis,
J. F. (2003). Physical activity and sedentary behavior: a
population-based study of barriers, enjoyment, and prefer-
ence. Health Psychol., 22: 178-188.
Sanada, K., Kearns, C. F., Midorikawa, T., and Abe, T. (2006).
Prediction and validation of total and regional skeletal muscle
mass by ultrasound in Japanese adults. Eur. J. Appl. Phys-
iol., 96: 24-31.
Schenkman, M., Berger, R. A., Riley, P. O., Mann, R. W., and
Hodge, W. A. (1990). Whole-body movements during rising
to standing from sitting. Phys. Ther., 70: 638-648.
Shaw, J. M. and Snow, C. M. (1998). Weighted vest exercise
improves indices of fall risk in older women. J. Gerontol. A
Biol. Sci., 53: M53-58.
Shores, K. A., West, S. T., Theriault, D. S., and Davison, E. A.
(2009). Extra-individual correlates of physical activity attain-
ment in rural older adults. J. Rural Health, 25: 211-218.
Slobounov, S. M., Moss, S. A., Slobounova, E. S., and Newell,
K. M. (1998). Aging and time to instability in posture. J.
Gerontol. A Biol. Sci., 53: B71-78.
Takai, Y., Sawai, S., Kanehisa, H., Kawakami, Y., and
Fukunaga, T. (2008). Age and sex diŠerences in the levels of
muscular activities during daily physical actions. Int. J. Sport
Health Sci., 6: 169-181.
Takeshima, N., Islam, M. M., Rogers, M. E., Koizumi, D.,
Tomiyama, N., Narita, M., and Rogers, N. L. (2014) Pattern
on age-associated decline of static and dynamic balance in
community-dwelling older women. Geriatr. Gerontol. Int.,
14: 556-560.
Takeshima,N.,Islam,M.M.,Rogers,M.E.,Rogers,N.L.,
3030
Eiji Fujita, et al.
Sengoku, N., Koizumi, D., Kitabayashi, Y., Imai, A., and
Naruse, A. (2013). EŠects of nordic walking compared to
conventional walking and band-based resistance exercise on
ˆtness in older adults. J. Sports Sci. Med., 12: 422-430.
Takeshima, N., Shimada, K., Islam, M. M., Kanehisa, H.,
Ishida, Y., and Brechue W. F. (2015). Progressive, site-
speciˆc loss of muscle mass in older, frail nursing home resi-
dents. J. Aing. Physi. Act., 23: 452-459.
Tinetti, M. E., Williams, T. F., and Mayewski, R. (1986). Fall
risk index for elderly patients based on number of chronic dis-
abilities. Am. J. Med., 80: 429-434.
Tinetti, M. E. and Speechley, M. (1989). Prevention of falls
among the elderly. N. Engl. J. Med., 320: 1055-1059.
Wolfson, L., Judge, J., Whipple, R., and King, M. (1995).
Strength is a major factor in balance, gait, and the occurrence
of falls. J. Gerontol. A Biol. Sci. Med. Sci., 50: 64-67.
Wolfson, L., Whipple, R., Derby, C. A., Amerman, P.,
Murphy, T., Tobin, J. N., and Nashner, L. (1992). A
dynamic posturography study of balance in healthy elderly.
Neurology., 42: 2069-2075.
Yamauchi, T., Islam, M. M., Koizumi, D., Rogers, M. E.,
Rogers, N. L., and Takeshima, N. (2005). EŠect of home-
based well-rounded exercise in community-dwelling older
adults. J. Sports Sci. Med., 4: 563-571.
Yoshioka, S., Nagano, A., Himeno, R., and Fukashiro, S.
(2007). Computation of the kinematics and the minimum
peak joint moments of sit-to-stand movements. Biomed. Eng.
Online, 6: 26.
Yoshitake, Y., Takai, Y., Kitamura, T., Kawanishi, M., and
Kanehisa, H. (2011). Body mass-based exercise in middle-
aged and older women. Int. J. Sports Med., 32: 924-928.
Name:
Eiji Fujita
A‹liation:
Senior Assistant Professor, Department
of Sport and Life Science, National In-
stitute of Fitness and Sports in Kanoya
Address
1 Shiromizu, Kanoya, Kagoshima 891-2393 JAPAN
Brief Biographical History and Work
Eiji Fujita is the Senior Associate Professor at Department of
Sport and Life Science, National Institute of Fitness and Sports
in Kanoya (2008-). He obtained his Ph.D. at National Institute
of Fitness and Sports in Kanoya in 2012. His research interests
are on health promotion, exercise gerontology and prevention
of sports injury.
Fujita E, Kanehisa H, Yoshitake Y, Fukunaga T, Nishizono H.
Association between knee extensor strength and EMG activities
during squat movement, Medicine & Science in Sports & Exer-
cise, 43(12): 2328-2334, 2011.
Membership in Learned Societies
Japan Society of Physical Education, Health and Sport
Sciences
Japan Society of Physical Fitness and Sports Medicine
Japanese Academy of Budo