Training for improved neuro-muscular
control of balance in middle aged females*
Gregory S. Anderson, PhD a,*, Fabio Deluigi, BKin b, Guido Belli, PhD b, Claudio Tentoni,
PhD c,
Michael B. Gaetz, PhD d
a Office of Applied Research & Graduate Studies, Justice Institute of British Columbia, New Westminster, BC, Canada
b School of Pharmacy, Biotechnology and Motor Sciences, University of Bologna, Italy
c Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy
d Department of Kinesiology and Physical Education, University of the Fraser Valley, Chilliwack, BC, Canada
Summary This study examined improvements in static balance and muscle electromyographic (EMG) activity following a four week progressive
training program in 16 middle aged females (mean age Z 46.9 ± 8.7 yrs; height 161.1 ± 6.0 cm; weight 65.4 ± 11.2 kg). Participants trained 3
times per week for 4 weeks, for 50 min per session, progressing base of support, stability, vision, resistance and torque in each of six basic
exercises. Pre and post training measures of balance included feet together standing, a tandem stance and a one-leg stand (unsupported leg in
the frontal plane) performed with the eyes closed, and a Stork Stand (unsupported leg in the frontal plane) with both eyes open and closed. In
each position postural deviations were tallied for each individual while muscle recruitment was determined using root mean squared (RMS)
EMG activity for the soleus, biceps femoris, erector spinae, rectus abdominis and internal oblique muscles of the dominant foot side. Balance
scores were significantly improved post training in both the Balance Error Score System (p < 0.05) and stork stand positions (p < 0.01). Muscle
activity was reduced post-training in all muscles in each condition except the soleus in the tandem position, although not all significantly.
Reduced biceps femoris activity suggest that improved core stability allowed participants to move from a hip to an ankle postural control
strategy through improved coordination of muscles involved inbalance and reduced body sway. The core muscles were able to control body
position with less activity post training suggesting improved muscle coordination and efficiency. These results suggest that short term
progressive floor to BOSU™ balance training can improve standing balance in middle aged women.

Research Performed at: University of the Fraser Valley, 33844 King Road, Abbotsford, British Columbia V2S 7B4, Canada.

Corresponding author. Justice Institute of British Columbia, 715 McBride Blvd, New Westminster, British Columbia V3L 5T4, Canada. Tel.: þ1 604 528 5617; fax: þ1
604 528 5518.
E-mail address: ganderson@jibc.ca (G.S. Anderson).

1

Introduction
Balance can be defined as the ability to maintain the body’s center of gravity (COG) over its base of support (BOS) with minimal sway or
maximal steadiness (Emery et al., 2005). Control of balance in upright body position is important for movements necessary not only for
operating activities of daily living, but for high level sport activities or prevention of musculoskeletal injuries (Kollmitzer et al., 2000;
Saeterbakken and Finland, 2013). To achieve balance or postural stability, the body coordinates four systems: somatosensory, visual,
vestibular, and musculoskeletal systems. If balance is perturbed, the body reacts through automatic postural reactions eliciting increased
muscle tone while the CNS monitors the sensory inputs to find the most efficient muscle output that will regain balance and provide good
stability. The synergy between muscles of the leg and trunk creates stable upright posture. The coordinated arrangement of postural muscle
activation employed in response to perturbation exists to simplify control of posture and movement and is referred to as postural synergy
(Stemmons and Sahrmann, 1999).
To train balance visual input, size of the base of support, and modifications to the foot support surface are often employed. Current training
methods demonstrate the utility of narrowing the base of support (i.e. stand on one foot as opposed to two) (Henry et al., 2001; Saeterbakken
and Finland, 2013); closing the eyes reducing visual input (Winter et al., 1998; Lord, 2006; Baumberger et al., 2004); and/or introducing
unstable working surfaces (i.e. wobble board, Swiss ball, or BOSU™ balance trainer) to progressively challenge the balance control mechanisms
(Cosio- Lima et al., 2003; Silfies et al., 2005).
Researchers and trainers that promote training on un- stable platforms claim that utilizing equipment like the Stability Ball, wobble board and
BOSU™ Balance Trainer provides a greater stress to the global and local stabilizing muscles (Anderson et al., 2013; Myer et al., 2005; Norwood
et al., 2007; Behm et al., 2010). It has been hypothesized that performing exercise in an unstable environment stresses the synergistic and
stabilizing muscles around a joint system for any given movement providing a more specific and functional form of training. Several authors
report increased core muscle activation when utilizing un- stable surfaces (Behm et al., 2002, 2005; Willardson, 2007; Hibbs et al., 2008),
Willardson et al. (2007, 2009) suggesting a direct link between training on unstable surfaces and core training exercises.
While studies have reported improved neuromuscular control of balance using different kinds of instability de- vices in injured or aged
individuals, the effect of a short term, specific training program performed using transitionsin vision, base of support and surface stability have
yet to be explored. For that purpose this work examines changes in balance and neural coordination of muscles involved in body control and
standing balance following a short, four week training program focussing on progressive exercise moving from a stable floor condition to
instability on the BOSU™ Balance Trainer, from two to one foot stance, and from eyes open to eyes closed conditions. Specific hypotheses
include:
1) Balance will improve significantly over the four weeks of progressive training
2) Global muscular electromyographic activity will decrease at the post intervention measurement
3) Biceps femoris activity will decrease as individuals control body sway through core stabilization and ankle postural control strategies.

Methods
Eighteen middle aged females participated in repeated measurements of pre and post training balance using standing posture with two feet
together (2 feet), a Tandem Stance with one foot in front of the other (Tandem), 1 leg standing on the non dominant (1 Leg) with the eyes
closed, and a Stork Stand with both eyes open (SS EO) and eyes closed (SS EC). Muscle recruitment was determined using root mean squared
(RMS) EMG activity in internal oblique (IO), rectus abdominis (RA), erector spinae (ES), biceps femoris (BF) and soleus (SO) muscles.
Subjects were recruited as volunteers from university faculty and staff. Each performed an orientation to the study and the tests and measures
at least three days prior to testing at which time subjects were screened for health issues that would limit participation using a Physical Activity
Readiness Questionnaire (PAR-Q). Each participant provided written informed consent prior to participating in the study which was approved
by the institution’s research ethics board.

Training procedures
Participants trained 3 times per week for 4 weeks, for 50 min per session. Training included a progression from floor to BOSU unstable surface,
eyes open to eyes closed conditions, static to dynamic exercise, from two to one foot, and progressed to include offcentred forces (torque).
The training focus was defined using variations of 6 specific exercises (Table 1). All exercises were progressed in relation to improvement in
both static and dynamic balance:

2

Table 1

Training exercises with progression.

Exercise

Stable unstable

Static/dynamic

Eyes open/closed

Resistance

1 leg standing

Standing on the floor/
BOSU

Standing/standing with
arm movement

Standing with eyes open/
closed

Squat

Squat on the floor/BOSU

Squat with partner

Squat “hand to hand
contact” on the floor/
BOSU

Lateral Bound

2 feete1 foot lateral
bound on the floor/BOSU

Kneeling on BOSU

Kneeling on BOSU

Static squat/dynamic
squat
Squat “hand to hand
contact” static on the
floor/BOSU and during a
dynamic squat
Lateral bound/bound
with partner
destabilization
Kneeling on BOSU/
kneeling with arm
movement

Squat on the floor with
eyes open/closed
Static “hand to hand
contact” squat on the
floor/BOSU with eyes
open/closed
Lateral bound on the
floor/BOSU eyes open/
closed
Kneeling eyes open/
closed

Standing on the floor/
BOSU with catching a
medicine ball
Squat on the BOSU
with medicine ball
Lateral bound on the
BOSU with medicine
ball catch

Torque

Torque on the floor/
BOSU with medicine ball
throw/catch

Dynamic torque with
medicine ball throw/
catch

Torque on the floor eyes
open/closed with
medicine ball and
partner

Lateral bound on the
floor/BOSU with
medicine ball hold
Kneeling with
medicine ball holding
and partner
destabilization
Torque on BOSU with
partner
destabilization

week 1 and 2 were performed using the floor and BOSU with the eyes open with no external load; week 3 and 4 increased the exercise’s
difficulty by introducing a medicine ball and the eyes closed condition (Table 1).
The total number of exercises per session increased weekly from 6 in week one to 12 in week 4. Similarly, the number of repetitions per set
increased from 8 in week one to 14 in week 4. Each variable increased by 2 each week. In all sessions participants were asked to focus on
“core” muscle activation to stabilize the body.

Balance testing procedures
Static balance was assessed using components of the BESS e Balance Error Score System (Riemann et al., 1999). This test is a quick and
practical balance evaluation method demonstrated to be safe and efficient in previous studies (Susco et al., 2004; Valovich et al., 2003) and as
a clinical evaluation of balance that usually has moderate to good reliability (Bell, 2011). While BESS has a learning effect in healthy and
neurological patients (concussion specially) (Mulligan et al., 2013), all participants performed the BESS 2 times during their orientation to the
study, and practiced once on the day of data collection prior to testing.
The BESS is normally performed barefoot on a firm sur- face by holding 3 different positions for 20 s each one in both eyes open and eyes
closed conditions. This study utilized only the eyes closed condition, and added the stork stand as one of the measures in both eyes open and
eyes closed conditions (see Table 2). While completing the BESS participants held each position with hands on the iliac crests while trying to
maintain optimal stability without body movement. During each test three investigators observed each subject and assigned the value “1” for
every balance fault; the median value was used when there was a discrepancy, and the final score was obtained by counting the total number
of errors in all positions, and by summing them separately for the eyes open and closed condition. The following body movements were
considered an “error”:







lifting hands from the iliac crest (one or both)
opening eyes (only in eyes closed condition)
stepping, stumbling or falling
remaining out of the position for more than 5 s
moving the hip through more than 300 of abduction or flexion
lifting forefoot or heel

During each testing session (pre and post), subjects were re-introduced to each test and were able to practice each test position prior to
testing.

Surface electromyography
Surface EMG recording locations were measured from five muscle groups (Anderson et al., 2013; Behm et al., 2002; Cram et al., 1998); Rectus
Abdominus (muscle bellies lateral to the umbilicus), Internal Obliques (2.5 cm medial from the anterior superior iliac spine), Erector Spinae (2
cm lateral to L5-S1), Bicep Femoris (mid-belly of the long head), Soleus (mid-point between medial malleolus and medial condyle of the tibia).
Each EMG site was shaved, cleansed with alcohol, and abraded with inter-electrode distances of approximately 2.5 cm positioned parallel to

3

the orientation of the fibres being measured.
Surface EMG activity was recorded using Grass Model 10A amplifiers with a digital interface. Electrical activity was recorded using 17
silveresilver chloride disposable electrodes applied to the skin’s surface (16 EMG electrodes and a ground). Electrode impedances were
maintained below kU. Filter settings were 10 Hz for the low filter and
Table 2

BESS and stork stand positions.

BESS position

Eyes

Description

Double leg stance

Closed

Standing both feet in contact with the floor and each other

Tandem stance

Closed

Standing with the heel of the dominant foot
(front foot) touching the toe of the non
dominant foot (back foot)

One leg stance

Closed

Single leg standing (non dominant leg) while
maintaining 900 of knee flexion with the dominant
leg, thighs parallel

Stork stand

Open and closed

Single leg standing (dominant leg) while maintaining
contact between medial knee and contralateral plantar
surface of the foot

1000 Hz for the high filter. The recording epoch was five seconds at a sample rate of 2000 Hz. All data were digitized using a National
Instruments AT-MIO-16F-5 A-D card and stored on a CD. The data were smoothed using a 10-point moving average and root mean squares
(RMS) were calculated for time-series using a Microsoft EXCEL spreadsheet.

Statistical analysis
Results for the BESS and Stork Stand were analysed separately using repeated measures analyses of variance to examine the global muscle
RMS EMG activity. SPSS v13 was used to perform a 2 (time) x 5 (muscle) x 3 (position) analysis of variance (ANOVA) with repeated measures to
evaluate the effects across the BESS test, and a 2 (time) x 5 (muscle) x 2 (position) analysis of variance (ANOVA) with repeated measures to
evaluate the effects across the Stork Stand. Differences in muscle recruitment in the biceps femoris (hip strategy) and soleus (ankle strategy)
were examined using a 1 (muscle) x 2 (time) x 3 (position) repeated measures ANOVA for the BESS, and 1 (muscle) x 2 (time) x 2 (position) for
the stork stand. When differences were detected by ANOVA pairwise comparisons were per- formed adjusted for multiple comparison through
use of Bonferroni correction. Paired T Tests were used to analyse positional errors in BESS and global RMS activity (separately
for BESS and Stork Stand) in pre-post training comparisons. The level of significance was set at p < 0.05.

4

Table 3 Balance positional error scores from the BESS and
stork stand pre and post training.
2 Feet-EC Tandem-EC 1 Leg EC Stork-EO Stork-EC
Mean
SD
Mean
post
SD

Results
Eighteen apparently healthy females (mean age Z 46.9 ± 8.7 yrs; height 161.1 ± 6.0 cm; weight 65.4 ± 11.2 kg) with no known balance
issues participated in the present study with pre and post training measures of balance and muscle activity during static posture balance
positions, and included activities with the eyes open and closed. Only participants who attended 80% of the sessions were included in the
statistical analysis, with 16 participants completing at least 10 of the 12 workout sessions and included in this analysis. The two participants
excluded from the study continued for the four weeks but cited work time pressures as their reason for low attendance (7 and 9 of 12 sessions)
at training sessions.

Balance positional errors
The mean number of positional errors during the BESS and stork stand decreased in each position with the exception of the BESS two feet with
eyes closed (see Table 3). During the BESS positions, the sum of positional errors for all participants combined decreased from 67 pre-training
to 44 post training (t Z 1.74; p < 0.05) moving from “broadly normal” to “above average”. During the stork stand the sum of positional errors
for all participants combined decreased from 100 pre training to 59 post training (t Z 2.97; p < 0.01).

BESS muscle activity
The Repeated Measures ANOVA (2 x 5 x 3) demonstrated a significant main effect for test conditions (F Z 6.91; p Z 0.00), between muscles (F Z
39.40; p Z 0.00) and importantly, time (pre and post-training) (F Z 5.28; p Z 0.03), with significant Test x Muscle (F Z 4.72 p Z 0.00). The test x
Time (F Z 3.09; p Z 0.06) interaction approached significance. Mean muscle RMS reductions for each test are reported in Table 4, and for each
test in Fig. 1.
Surface electromyographical RMS decreased for all muscles in all positions with exception of the soleus during the Tandem position, even if not
significantly (p > 0.05). Global RMS activity (EMG in Tandem, 1 leg and 2 Feet together) decreased significantly in both the rectus abdominis
and biceps femoris (p < 0.01) when comparing pre- and post-training. A one way ANOVA for the biceps femoris found muscle activity to be
lower in post training compared to pre training (9.09 vs 13.87; F Z 4.81, p Z 0.04) and the 1 Leg position showed higher muscle activity
compared to Tandem positions, independently for time (F Z 7.17; p Z 0.00); no differences were detected in Time x Test interactions (F Z 2.61;
p Z 0.09).
A one way ANOVA for soleus found a significant main effect (F Z 5.62; p Z 0.00) with EMG activity significantly lower in the 2 Foot position
compared to tandem and 1 leg (respectively p Z 0.00 and p Z 0.04); EMG in all positions decreased in post training compared to pre training,
even if not significantly for the time factor and time x test inter- action (p > 0.05).

Stork stand muscle activity
The Repeated Measures ANOVA (2 x 5 x 2) demonstrated a significant main effect for test conditions (F Z 21.80; p Z 0.00), between muscles (F
Z 19.61; p Z 0.00) and time (pre and post-training) (F Z 8.76; p Z 0.01), with significant Test x Muscle (F Z 3.89; p Z 0.00) interactions. In both the
eyes open and eyes closed stork stand positions, during the eyes closed condition muscle EMG activity were higher for each muscle (see Fig. 2).
Similarly, the muscle EMG activity was reduced in each muscle post training in each condition even if significant only in the biceps femoris and
soleus for EC (p < 0.05 e Table 5). Global RMS activity (EMG in Stork Stand EO and EC together) decreased significantly in all muscle (p < 0.05)
with exception of OI (p > 0.05) for pre-post training comparison.
A one way ANOVA for biceps femoris evidenced significance for test (F Z 37,159; p Z 0.00), time (F Z 11.56; p Z 0.00) and time x test interaction
(F Z 7.52; p Z 0.01). EMG activity was lower in post training compared to pre training in EC (20.82 vs 36.19; p Z 0.00) and EO (7.99 vs 11.17; p Z
0.07) with significance only in the EC condition; EMG activity was significantly higher in EC compared to EO in both pre and post training
conditions (p Z 0.00).
A one way ANOVA for soleus evidenced significance for test factor (F Z 57,315; p Z 0.00), time x test interaction (F Z 5.34; p Z 0.03) while the
time factor (F Z 3.65;

5

Table 4 EMG values for all muscles in BESS positions pre and post-training. RA: Rectus Abdominis; IO: Internal Oblique; ES:
Erector Spinae; BF: Biceps Femoris; S: Soleus. *Significantly different in pre-post comparison (p < 0.05).

RA
2 feet
SD
Tandem
SD
1 leg
SD
Global muscle RMS
SD

IO

ES

BF

S

Pre

Post

Pre

Post

Pre

Post

Pre

Post

Pre

Post

5.05
2.42
5.32
2.65
5.66
2.78
5.34
2.55

4.16
1.23
4.33
1.26
4.46
1.12
4.31*
1.13

7.01
7.46
9.35
7.05
12.92
15.38
9.76
10.23

6.89
7.56
7.80
5.75
8.46
5.70
7.71
6.21

7.45
6.26
10.32
8.09
14.33
10.59
10.69
8.24

7.21
7.93
8.67
7.42
9.81
6.77
8.56
6.99

8.40
7.68
11.53
9.82
21.68
17.22
13.87
12.32

5.09
5.24
10.36
14.13
11.84
7.26
9.09*
9.84

16.70
16.97
27.93
9.45
51.98
63.20
32.20
39.80

16.38
16.51
28.56
17.41
33.06
12.58
25.99
16.44

Figure 1 BESS position muscle comparison pre-post training. 2 FT: 2 Feet Standing; TAN: Tandem Position; 1 LEG: 1 Leg Standing; RA: Rectus
Abdominis; IO: Internal Oblique; ES: Erector Spinae; BF: Biceps Femoris; S: Soleus.

Figure 2 Stork stand muscle comparison pre-post training. SS EO: Stork Stand Eyes Open; SS EC: Stork Stand Eyes Closed; RA: Rectus
Abdominis; IO: Internal Oblique; ES: Erector Spinae; BF: Biceps Femoris; S: Soleus.

6

Table 5 EMG values for all muscles in stork stand positions pre and post-training. RA: Rectus Abdominis; IO: Internal Oblique;
ES: Erector Spinae; BF: Biceps Femoris; S: Soleus. *Significantly different in pre-post comparison (p < 0.05). y Significantly
different pre-post comparison (p < 0.05). z Significantly different EC e EO comparison (p < 0.05).

RA
Pre

Post

IO
Pre

Post

ES
Pre

Post

BF
Pre

Post

S
Pre

Post

Stork stand EO

5.30

4.39

11.91

6.55

9.68

7.71

11.17

7.99y

26.31

24.73y

SD
Stork stand EC
SD
Global muscle RMS
SD

2.73
8.86
5.93
7.08
4.76

1.11
5.43
1.71
4.91*
1.47

19.08
30.71
60.45
21.31
44.79

6.13
22.28
34.53
14.42
25.30

6.92
20.28
12.45
14.98
10.80

6.38
15.01
11.63
11.36*
9.61

9.70
36.19z
22.22
23.68
20.11

5.69
20.82z
14.55
14.41*
12.29

11.58
51.30z
23.62
38.80
20.29

11.62
40.49z
17.47
32.61*
15.91

p Z 0.07) approached significance. EMG activity was lower post training compared to pre training in EC (40.49 vs 51.30; p Z 0.04) and EO (24.73
vs 26.31; p > 0.05) with significance only in EC; EMG was significantly higher in EC compared to EO in both pre and post training conditions (p Z
0.00).

Discussion
This study examined the effects of a 4 week targeted neuromuscular training program for the improvement of balance and neuromuscular
control of standing postures in middle aged females. Improvements in balance have been reported in various populations following a 6e8 week
training program incorporating the Swiss Ball (Sekendiz et al., 2010), uniaxial or multiaxial unstable surfaces (Eisen et al., 2010), resistance
training incorporating unstable surfaces (Sparkes and Behm, 2010; Schilling et al., 2009), core stability (Aggarwal et al., 2010) and progressive
neuromuscular training (Filipa et al., 2010). The pre- sent results extend the past literature demonstrating the ability of a short, four-week
targeted training program to increase balance in middle aged women (as documented by reduced positional errors during the BESS) through
the manipulation of training variables that included base of support, stability, vision, resistance and torque.
DiStefano et al. (2009) demonstrated a short term training programs (4 weeks) was effective in improving static and dynamic balance in stable
or unstable conditions. While there were no significant decreases in muscles EMG recorded activity between pre and post training in the
present study, muscle activation was reduced in all muscles during each of the BESS positions (with the exception of the soleus muscle in the
Tandem position), and during both the eyes open and eyes closed Stork Stand. Reduced EMG activity was hypothesized with increased
coordination of neural control patterns and reduced co-activation of muscles. Anderson and Behm (2005) report that muscle tension at only
30e40% of maximal voluntary contraction can be effective in stabilizing the core with proper training and muscle activation patterns. Intensive
training of motor skills may reduce the neural effort required to perform a task, with the automation of the motor response moving neural
activation from higher (cortical) to lower brain centres (basal ganglia and cerebellum) (Schubert et al., 2008). These authors report a reduced
corticospinal excitability during the trained task after 4 weeks of training as a result of increased motor efficiency and automatic movement
control, supporting the notion that improved motor efficiency may underlie the reduced EMG activity found in the present study post training.
Training in the present study included a progression from floor based activities to activities performed on the BOSU ball dome (unstable
surface), utilized progressive change in visual input through using eyes open to eyes closed conditions, purposefully manipulated the base of
support from two to one foot in each of the stable and unstable conditions, moved from static to dynamic exercise, and progressed resistance
with the inclusion of off centred forces (torque). The training focus was defined using variations of specific whole body activities. With reduced
muscular activity to maintain balance and posture post training (in all but the soleus in the Tandem position), the present study supports the
notion that activities that stress the neuro- muscular coordination of whole body movement are efficient in increasing balance (Myer et al.,
2005; Hibbs et al., 2008; Willardson, 2007; Filipa et al., 2010). The single Leg BESS position and Stork Stand were most challenging, and support
the results of Saeterbakken and Finland (2013) who found single leg standing (with reduced base of support) and unilateral exercises
(introducing torque) to best in- crease superficial core muscle activation.
Training on unstable surfaces, exposing individuals to altered sensory input, is reported to increase muscular stress (Anderson et al., 2013) and
may lead to gains in stability, proprioceptor activity, sway control, and improved core stability through neuro-adaptive mechanisms (Aggarwal
et al., 2010; Schilling et al., 2009; McNeill, 2010). Anderson et al. (2013) recently demonstrated that as the level of instability increased during a
push-up protocol, there was a greater amount of muscle activation for the core stabilizers, prime movers and lower body stabilizers. Similar
results were found by Norwood et al. (2007) during a bench press, with significant in- creases in EMG with increasing instability of both the
upper and lower body, and both. While muscular activity pat- terns present differently with variation in postural perturbation (Henry et al.,
2001; Winter et al., 1998), muscle force output is significantly greater for the majority of muscles when they are trained under unstable
conditions through enhanced motor unit recruitment (Behm et al., 2002). Importantly, as stated previously, Schubert et al. (2008) found
reduced motor cortical in fluence during the trained tasks following balance training on unstable surfaces with both eyes open and eyes closed
activities. Shifting to the lower level of CNS neuromuscular control allowed for increased the rate of force development, and would allow for a
more rapid response to perturbations in the balance system. These findings are consistent with the position that unstable surfaces in
conjunction with standard exercises can be used to improve the motor coordination and control which may be beneficial to improving the
performance of standing balance activities (Kaji et al., 2010), and are supported by the results of the present study.
When the sensory systems are systematically manipulated (closing the eyes or adding vibration), body sway is affected (Winter et al., 1998).
When participants close their eyes, body sway increases by 20%e70% (Lord, 2006). The interaction between visual, vestibular and
proprioceptive information is crucial for maintaining appropriate biomechanical alignment (Lepers et al., 1997), and should be considered

7

important training variables. For example, during the stork stand in the present study the global muscle activity was higher during the eyes
closed condition in both pre and post training conditions, and the training effect demonstrates larger reductions in global muscle activity in the
eyes closed condition.
Successful completion of activities of daily living occur as a result of adapting postural strategies for different standing positions to maintain
equilibrium (Henry et al., 2001). Henry et al. (2001) found that altering the foot position (affecting the available base of support) resulted in
changes in the stiffness of the musculoskeletal system. Results of the present study reinforce previous results, and suggest that manipulation
of base of support may modify the neural control of equilibrium Training programs to modify the balance strategy used, and the degree of
muscle activation required, should include manipulation of base of support. Further, the effect of modifying base of support may be
exemplified when there are modifications in vision from eyes open to eyes closed. Such changes are demonstrated in the present work with
the reduced biceps femoris activity, suggesting a reduced hip corrective strategy for balance, and improved efficiency with reduced muscle
activity required post training.

Conclusion
The ability to report significant findings across all measures in present study was limited by a small sample size and short training period;
however, while all muscle EMG results did not reach significance from pre- to post-training, favourable changes in stabilizing muscles were
observed and balance in a standing position improved post training. Improved balance with reduced muscle EMG activity may suggest that the
improved coordination of muscles involved in balance reduced body sway post training; the core and postural muscles were able to control
body position with less activity post training suggesting improved muscle coordination and efficiency. Such findings over a short four week
program are promising, suggesting that short duration programs may be of benefit physiologically and may have greater appeal to participants
and less costs than longer duration programs. These results support the use of progressive balance training to improve bi- and uni-pedal
standing balance in middle aged women, particularly in the more challenging eyes closed condition.

Acknowledgement
Fabio Deluigi received a scholarship from the University of Bologna, Faculty of Exercise and Sport Science to perform research in Canada to
fulfil the requirements of his undergraduate thesis. The Associate Vice President of Research from the University of the Fraser Valley provided
funding for purchase of electrodes.

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