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ELECTROMYOGRAPHIC ANALYSIS OF UPPER BODY,
LOWER BODY,AND ABDOMINAL MUSCLES DURING
ADVANCED SWISS BALL EXERCISES
PAUL W.M. MARSHALL
1
AND IMTIAZ DESAI
2
1
School of Biomedical and Health Science, University of Western Sydney, Sydney, Australia; and
2
Department of Sport and
Exercise Science, University of Auckland, Auckland, New Zealand
ABSTRACT
Marshall, PWM and Desai, I. Electromyographic analysis
of upper body, lower body, and abdominal muscles during
advanced Swiss ball exercises. J Strength Cond Res 24(6):
1537–1545, 2010—Although there is now some evidence
examining the use of a Swiss ball during core stability and
resistance exercises, this has commonly been performed using
basic or isometric exercises. There is currently no evidence
examining more advanced Swiss ball exercises. The purpose
of this study was to determine whether or not muscle activity
measured during advanced Swiss ball exercises was at an
approximate intensity recommended for strength or endurance
training in advanced, or novice individuals. After a familiarization
session, 14 recreationally active subjects performed 6 different
‘‘advanced’’ Swiss ball exercises in a randomized order. The
primary dependent variables in this study were the activity
levels collected from anterior deltoid, pectoralis major, rectus
abdominis (RA), external obliques, lumbar erector spinae,
vastus lateralis (VL), and biceps femoris using surface electro-
myography. All signals were normalized to maximal voluntary
isometric contractions performed before testing for each mus-
cle. The results of this study showed that the Swiss ball roll
elicited muscle activity in triceps brachii (72.5 632.4%) and VL
(83.6 644.2%) commensurate with the intensity recommen-
ded for strength exercises in advanced trainers. Rectus
abdominis activity was greatest during the bridge exercise
(61.3 628.5%, p#0.01). This was the only exercise to elicit
RA muscle activity commensurate with a strength training
effect. The remainder of the exercises elicited abdominal activity
that would require a higher number of repetitions to be perfor-
med for an endurance training adaptation. Although this study
has provided evidence for one advanced Swiss ball exercise
providing a significant whole-body stimulus, the practical
difficulty and risks of performing these more complicated
Swiss ball exercises may outweigh potential benefits.
KEY WORDS surface electromyography, exercise intensity,
strength training, labile surface
INTRODUCTION
The Swiss ball is an unstable training device used
to increase the difficulty of various bodyweight
and traditional free-weight resistance exercises (3).
An English physiotherapist by the name of Mary
Quinton is cited as having first started to use Swiss balls with
children who had cerebral palsy in 1958 (33). A Swiss
therapist then introduced the idea of using these balls to
Dr. Susanne Klein Vogelbach, who started using them
with her physiotherapy students and clients with orthopedic
problems. Dr. Vogelbach later published a book detailing the
Swiss ball exercises she developed over her years in clinical
and teaching practice (23). Recently, research has investi-
gated the use of Swiss balls during exercise using electro-
myography to quantify the activity of the various muscle
groups involved. Some of the greatest interest in the use of
Swiss balls is in the application during body-weight exercises
that involve no added external resistance. This is widely
accepted as being one of the defining modes for a type of
training known as ‘‘core stability’’ exercise. The description of
a ‘‘core stability’’ exercise relates to how a movement, usually
involving bodyweight only for resistance, provides a training
stimulus for the trunk musculature. Although evidence exists
regarding the use of the Swiss ball for increasing trunk muscle
activity during core stability exercises compared with stable
surface movements (27,42), these are commonly static or
simple tasks that do not use the ability of the ball to roll (17).
Moreover, evidence suggesting that Swiss ball exercises
are less effective than conventional resistance exercises for
trunk muscle activity only use basic movements such as
the quadruped, pelvic thrust, and back extension movements
for comparison (32). There is no evidence examining some of
the more difficult Swiss ball exercises that are observed in
the recreational gymnasium environment. Therefore, we are
unsure whether these more complex movements that take
Address correspondence to Dr. Paul W.M. Marshall, p.marshall@uws.
edu.au.
24(6)/1537–1545
Journal of Strength and Conditioning Research
Ó2010 National Strength and Conditioning Association
VOLUME 24 | NUMBER 6 | JUNE 2010 | 1537
advantage of the Swiss ball’s design and material properties
elicit muscle activity greater than that which has been
reported for conventional resistance exercises such as the
deadlift or squat.
When surface electromyographic (EMG) recordings are
rectified and smoothed, the amplitude has been shown to
be positively and linearly related to isometric force output
(1,9,14, 25). It has been suggested that EMG activity in excess
of 60% of a maximal voluntary isometric contraction (MVIC)
is required for strength training, with endurance benefits
resulting from exercise intensities below 25% (2,5,43). The
highest recorded trunk muscle EMG levels for Swiss ball
exercises we currently have information on are generally of
a moderate intensity. Abdominal activity of approximately
50% has been measured for Swiss ball curl-ups (42) and for
bilateral isometric leg holding (28). Activity of the back
extensors while using a Swiss ball ranges between 19.5 and
45.5% (15,32). These intensities may be appropriate for
eliciting a strength training effect in novice individuals (37)
and possibly an endurance effect if more repetitions are per-
formed by advanced individuals (12). In contrast to the Swiss
ball research we are currently aware of, trunk muscle activity
during conventional resistance exercises have been shown to
be appreciably greater.
Recent evidence has found that resistance exercises per-
formed with moderate intensities (ca. 50% of a 1 repetition
maximum) elicit greater trunk muscle activity than performing
basic Swiss ball exercises (32). Other research investigating
variations of the deadlift technique with moderate load
(12 repetition maximum) reported trunk and leg muscle
activity in excess of 60% MVIC (18). Although this research
clearly suggests that moderately loaded resistance exercises
elicit trunk and lower body muscle activity greater than that
elicited in the current body of Swiss ball research, advanced
Swiss ball exercises have not currently been evaluated.
Therefore, the purpose of this study was to measure
normalized muscle activity using surface EMG from
abdominal, lumbar, and upper and lower body musculature
during supposedly more difficult Swiss ball exercises. This
will allow comparison of these exercises to what has been
previously measured in the literature for Swiss ball exercises,
and comparison to muscle activity levels reported for con-
ventional resistance exercises. The hypothesis of this study
is that all of the advanced Swiss ball exercises measured
will elicit trunk muscle activity in excess of 60% MVIC and
that exercises involving an upper or lower body focus will also
elicit muscle activity in those regions commensurate with
a strength training effect.
METHODS
Experimental Approach to the Problem
A within-subject cross-sectional experiment was performed
to examine normalized muscle activity using surface EMG
during several advanced Swiss ball exercises. No comparison
to a stable surface was performed because these exercises
could only be performed using a Swiss ball. Subjects
participated in 2 sessions. The first was a familiarization
session where the subjects were trained in how to perform the
specific exercises by an experienced practitioner. Subjects
were not provided with a Swiss ball to continue practicing
these exercises, and all individuals were asked to refrain
from attempting these movements in their personal training
sessions. One week later, subjects attended the testing session
where 3 repetitions of each exercise were performed while
surface EMG was continuously recorded. Before testing,
MVICs were performed for each muscle to normalize the
measured activity during testing. The order of exercises was
randomized among subjects.
Subjects
A power calculation was performed using the results of
a previous study for the difference in triceps EMG between the
Swiss ball and a stable surface for a push-up exercise because
this most closely resembles one of the starting positions used in
this study (28). The calculation of the sample size was carried
out with a= 0.05 (5% chance of type I error), 1 2b=0.80
(power 80%), and a calculated effect size of d= 1.41. This
provided a sample size of n= 14 for this study.
Fourteen healthy, recreationally active subjects volunteered
to participate in this study after providing informed written
consent (7 men and 7 women, aged 24.1 61.7 years; height
1.74 60.08 m; and weight 72.9 613.1 kg). The University
Human Participants Ethics Committee approved all proce-
dures used in this investigation. All subjects had been per-
forming regular physical activity on at least 3 days per week
for the last 3 months including both aerobic and resistance
training modalities. Although some of these subjects had
experience using a Swiss ball for exercise, no subject reported
regular training on a Swiss ball or familiarity with any of
the exercises tested in this study. No subject reported current
or recent participation in a competitive, organized sports
competition. Subjects reported that they were not taking
performance-enhancing stimulants at the time of testing
and had no musculoskeletal injuries or disorders. Subjects
were instructed to refrain from any resistance or anaerobic
exercise and were required to maintain normal dietary habits
in the 24 hours before the testing session. Subjects were
required to present to testing in a 2-hour postprandial state.
Procedures
Electromyographic Measurement and Analysis. After careful
skin preparation using disposable razors to remove excess
hair, fine sandpaper, and isopropyl alcohol swabs to reduce
electrode impedance to below 5 kV(measured using a digital
multimeter), pairs of Red Dot silver/silver-chloride electrodes
(3M, St. Paul, MN, USA) with a 3-cm center-to-center
distance were applied to the following muscles on the right
hand side of the body only, aligned in a parallel arrangement
to the muscle fibers. Rectus abdominis (RA), internal obliques
(IO), erector spinae (ES), pectoralis major (PM)–clavicular
placement, anterior deltoid (AD), lateral head of triceps
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brachii (TB), vastus lateralis (VL), and biceps femoris (BF)
(13). If the measured impedance was above 5 kV, the
electrodes were removed, and preparation procedures
were performed again. The most common sites that involved
additional preparation were the abdominal sites in the male
subjects owing to not removing sufficient hair in the first
preparation. Crosstalk is an issue to address in surface EMG
recordings. To minimize crosstalk, each pair of electrodes
was placed according to previous recommendations for ideal
anatomical placement (13) to ensure that electrodes were
well within the borders of the target muscles. This included
measurements to relevant bony landmarks and other
prominences to maintain consistency of placement among
subjects. The IO site that was inferior and medial to the
anterior superior iliac spine has previously been validated
for anatomical placement (26).
Electromyographic signals were recorded using a Grass
Instruments data acquisition board (Grass-Telefactors, West
Warwick, RI, USA; common mode rejection ratio of 90 dB at
60 Hz; input impedance 100 MV,26-dB band pass roll off at
10 and 1,000 Hz) at 2,000 Hz with 16-bit analog to digital
conversion into a Pentium IV computer. Data collection and
analysis was conducted using LabVIEW (National Instru-
ments Corporation, Austin, TX, USA). All collected signals
were subsequently band pass filtered (between 10 and
500 Hz), then rectified and smoothed by using a root mean
square (RMS) calculation with a 50-millisecond sliding
window (19). The basis of the data analysis from the RMS
signal was identification of the greatest average 1-second
RMS from each muscle signal collected during each exercise
task. This was normalized to the MVIC measured for each
muscle before testing.
Procedures used for the MVIC for each muscle have
previously been presented (22,28). After familiarization with
the technique required, 2 MVICs were performed for each
muscle with at least 2 minutes of rest between trials (14).
The greatest RMS calculated from either trial was used as
the MVIC for the muscle. The MVIC procedures cannot be
expected to only elicit activity from the muscle of interest.
However, each movement was a prime movement for the
target muscle, performed at the midpoint of its length to
obtain the greatest amount of recruitment for normalization
of exercise intensities.
Exercise Procedures
Six different exercises were studied (Figure 1). However,
because the starting point for the Praying Mantis exercise
represents a position commonly used for exercise, this was
also measured to provide muscle activity recorded in a static
hold position as a representation for the type of exercises
previously reported in the literature. Therefore, 7 different
exercises were analyzed. The same solid surface was used
beneath the Swiss ball for all tests. This was a laboratory
nonslip surface that allowed the ball to roll but did not slip
and potentially be unsafe for testing. For the bridge and hold
and crunch exercises, a training mat was used to beneath the
participant only. Three trials were collected for each exercise
with a 1-minute break between each trial. The normalized
RMS for the 3 collected trials was averaged for each subject
to provide the muscle activity for each site for each exercise.
For all exercises, either a 55- or 65-cm diameter Swiss ball
was used depending on the height of each subject. The ball
was chosen based on whether an individual could lie prone
with their abdomen on the ball with their hands on the
ground directly underneath the shoulders and their spine in
a relatively neutral position.
Prone Hold and Praying Mantis
The prone hold position was a 4-second isometric contrac-
tion performed with the individual supporting themselves
on the Swiss ball with their forearms flat on the surface,
and their shoulders flexed to 90°. The Praying Mantis exercise
was performed separately to the isometric contractions but
using the hold as a starting position. For the Praying Mantis
exercise, the subject was required to rotate the ball 360°
clockwise, then 360°anticlockwise by moving the shoulder
girdle only (although adjustments in whole body posture
occurred these were not the focus of initiating ball move-
ment). The movement was instructed to be performed at a
natural, self-selected speed. The ball was maintained under-
neath the subject throughout the movement. The position of
the hands (linked via fingers) was used to indicate the 0°
starting point for the movement, and this was used to guide
the individual’s eyes for the degree of rotation. One trial
represented the full rotation in each direction.
Single Leg Squat
The ball was placed so that the lowest point of contact
was just superior to the ES electrodes (L5–S1 location).
Individuals were required to slowly lower themselves to 90°
of knee flexion, pause for 1 second, then stand back up. The
duration of individual trials never exceeded 4 seconds.
The contralateral thigh was required to be flexed to 90°,
and the shank left free although no ground contact was
allowed. Foot position was marked on the floor to ensure
consistency between trials. Foot position was based on the
individual being able to reach 90°of knee flexion at the
bottom of the squat with 90°of hip flexion. Three trials were
collected for the right and left leg squats. The greatest activity
was always measured for the right leg squat.
Hold and Crunch
Individuals were required to lie on the floor with their legs
flexed to 90°and their shoulders flexed to be placed on the
floor behind them. The Swiss ball was then placed between
their ankle joints. Recording commenced once the ball was
placed. The individual was required to hold the ball in place
for 1 second, then crunch up with a controlled movement
while maintaining full elbow extension but extending their
shoulders to take the ball out from between their legs, then
slowly return to the starting position with the ball in their
hands and legs flexed to 90°. This was one repetition.
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Bridge
Individuals were required to kneel on the floor with the ball
directly in front of them and their hands placed on the ball.
They were instructed to push the ball away from themselves
as far as possible while maintaining contact with the surface.
This involves lowering the trunk toward the ground and
flexing the shoulder until. The initial movement involved
alternating hands pushing the ball out, until both hands were
required for the final push to attain the fully extended bridge
(pivoting from the knees to allow maximal extension of
the body), which was maintained for 1-second. The hands
were maintained on the superior aspect of the ball to ensure
the subject was able to return to the starting position by
extending the shoulder downwards into the surface. This was
one trial. No trial exceeded 5 seconds in duration.
Hip Extension
Each individual was required to assume a full ‘‘roll-out’’
position with the ventral aspect to the feet only in full contact
with the ball and the ankle plantarflexed, with the hands
placed on the ground directly beneath the shoulders. The
individual was required to extend the hip only. The distance
Figure 1. Exercises performed in this study.
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Advanced Swiss Ball Exercises
of hip extension was based on limiting any torso rotation
(usually pivoting about the leg still on the ball) to aid greater
hip displacement. This ensured that only a hip movement
was tested. The hip movement was at a self-selected cadence.
At the limit of extension each individual attained, an isometric
contraction was maintained for 2 seconds, and then the leg
was lowered back onto the ball. This was one trial. No trial
exceeded 4 seconds in duration. Three repetitions were
performed for the right and left legs.
Roll
Each individual was required to lie supine on the ball with
the thoracic spine supported by the surface and their hands
linked by the fingers and placed on the xiphoid notch. This
movement involved rotation of the whole body to induce
rotation of the ball. To move the ball left, the right side of the
trunk is initially rotated into the ball, maintaining a relatively
rigid segment. The right leg is then required to be moved in
line with the trunk, and then the whole body is rotated into
a prone position with the right leg moving underneath the
supporting left leg. From this position, the individual was
required to rotate back to the starting position by initiating
movement of the right side of the body again into the ball.
Each trial consisted of moving from supine to prone to supine,
then repeating for the opposite side of the body (move the ball
right–left side of body initiates movement into the ball). Trials
were approximately 6 seconds in duration.
Statistical Analyses
The Statistical Package for the Social Sciences (SPSS Inc, v16.1,
Chicago, IL, USA) was used for analysis. Descriptive statistics
were calculated for all exercises for each muscle. A one-way
analysis of variance (ANOVA) was used to identify differences
between exercises for each muscle. Gender was entered as
a covariate in the analysis. If the main effect of the ANOVA was
significant, repeated contrast statistics and pairwise compar-
isons were used to identify where the differences were. The
level of significance for all data was p#0.05. Unless otherwise
stated, all data are presented as mean 6SD.
RESULTS
Gender was not a significant covariate in the analysis of
normalized EMG levels. The average normalized EMG levels
for each muscle during the exercise tasks are presented in
Tables 1–3.
Abdominal Muscle Activity
Rectus abdominis activity was greatest during the Swiss ball
bridge (Table 1; p#0.01). This was identified at the terminal
point of the bridge. The praying mantis, hold and crunch,
and roll exercises were not different from each other but
had greater activity than the remaining exercises (p#0.05).
Prone holds were different from hip extensions (p#0.05),
which were different from the single leg squats (p#0.001)
that had the lowest RA activity (2.1 62.5%) of all exercises.
Internal oblique activity was greatest during the Swiss ball
roll exercise (p#0.001). Swiss ball bridging, praying mantis,
and hip extension IO activity were not different but were
greater than the remaining exercises (p#0.05).
Erector spinae activity was greatest during the Swiss ball
roll exercise (p#0.001). Activities during hip extensions and
single leg squats were not different but were significantly
greater than the remaining exercises (p#0.05).
Upper Body Muscle Activity
Pectoralis major activity was greatest during Swiss ball roll,
praying mantis, and bridge exercises (Table 2; p#0.001).
Activity during hip extensions was different from the remaining
exercises only (p#0.001).
Anterior deltoid activity was
greatest during Swiss ball roll and
hip extension exercises (p#
0.001). Activity during the pray-
ing mantis was different from the
remaining exercises only (p#
0.001).
Triceps brachii activity was
greatest during the Swiss ball
roll exercise (p#0.001). Activ-
ity during praying mantis and
bridge exercises was different
from the remaining exercises
(p#0.001). Activity during hip
extensions and the prone hold
was greater than during the
hold and crunch and single leg
squat (p#0.001).
Lower Body Muscle Activity
Vastus lateralis and BF activities
were greatest during the Swiss
TABLE 1. Normalized muscle activity (% maximal voluntary isometric contraction) from
the abdominal muscles during the exercises performed in this study.*†
Exercise RA IO ES
Swiss ball bridge 61.3 628.5‡20.2 69.3§ 2.8 61.1
Swiss 40.1 621.3§ 14.0 68.2§ 6.6 65.8
Swiss ball hold and crunch 34.0 612.4§ 9.5 63.2 2.8 61.8
Swiss ball rolls 30.2 613.5§ 44.6 621.3‡54.3 628.7‡
Prone hold 23.2 611.6
k
6.5 63.6 1.9 61.4
Swiss ball hip extension 13.8 64.9{15.0 67.8§ 13.7 66.2§
Swiss ball single leg squat 2.1 62.5 7.3 65.8 10.0 67.3§
*RA = rectus abdominis; IO = internal obliques; ES = erector spinae.
†Values reported are mean 6SD.
‡For RA, IO, and ES, the identified exercise was significantly different from all other
exercises (p#0.05).
§These identified exercises were not different from each other, but were different from the
remaining exercises (p#0.05).
k
For RA, this exercise was different from the remaining exercises only (p#0.05).
{For RA, this exercise was different from the remaining exercise only (p#0.05).
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ball roll (Table 3; p#0.001). The high level of activity is
associated with the right leg being the primary support point
with a stable contact when the left side of the body is being
rotated. For VL, activity during the hip extension, praying
mantis, and single leg squat was greater than during the
remaining exercises only (p#0.001).
For BF, activity during hip
extension was greater than dur-
ing the remaining exercises (p#
0.001). This activity was mea-
sured in the test leg that was
held in isometric extension.
Biceps femoris activity during
the praying mantis was differ-
ent from the remaining exer-
cises (p#0.01).
DISCUSSION
This study has measured the
activity of upper body, abdom-
inal and lower body muscles
during several more advanced
Swiss ball exercises. It is impor-
tant to note that no falls or
injuries were sustained during
testing despite the difficult na-
ture of the exercises. This is probably owing to the use of
a familiarization session before testing. The speed roll exercise
was an especially difficult exercise to learn and perform owing
to the combined rotation of the body and ball. It is important
to note that these were recreationally active participants who
had a good level of physical fitness and strength. Owing to the
complicated nature of these exercises, caution should be taken
when prescribing these movements for the untrained
population.
A further consideration for the results of this study is that
the EMG for each exercise was analyzed from the greatest
1-second average activity during each trial. This may
have been during dynamic or isometric contractions for the
different exercises. This activity was then normalized
to MVICs, as is the standard procedure used in all studies
examining muscle activity during core stability exercises
(6,7,14–17,21,27,28,42). This may have introduced an over-
estimation of the activity of some exercises where significant
concentric actions are involved. It is expected that the
greatest EMG will be measured during the concentric phase
compared with isometric or eccentric actions (14). Some
exercises, such as the praying mantis and roll, cannot incor-
porate a focused isometric component. It is important to note
that some of the highest EMG levels measured in this study
(VL during the roll and RA during the bridge) were measured
during relatively isometric contractions. Despite the possi-
bility that relative activity levels are overestimated, we believe
that the measured patterns of activity accurately represent
the difficulty of each exercise.
Another consideration, which is normal for any EMG
study, is the considerably large SDs of the data. This suggests
that in the prescription of these exercises, some individuals
may find that they are more or less difficult than the average
activity indicated here. Finally, core stability of the spine is
a complex issue defined as combining the musculature, the
TABLE 2. Normalized muscle activity (% maximal voluntary isometric contraction) from
the upper body muscles during the exercises performed in this study.*
Exercise Pectoralis major Anterior deltoid Triceps brachii
Swiss ball rolls 40.7 625.6†37.7 616.4†72.5 633.4†
Swiss ball praying mantis 30.5 618.1†16.7 69.4‡27.1 615.7‡
Swiss ball bridge 27.0 68.8†5.5 64.6 28.0 610.1‡
Swiss ball hip extension 13.8 64.6‡29.0 616.3†14.4 63.1§
Swiss ball hold and crunch 7.7 64.3 7.4 65.4 1.6 62.1
Prone hold 5.8 64.1 4.1 65.2 12.4 65.9§
Swiss ball single leg squat 1.2 61.4 1.1 61.3 1.5 60.8
*Values reported are mean 6SD.
†For pectoralis major, anterior deltoid, and triceps brachii, the identified exercises were
significantly different from all other exercises only (p#0.05).
‡These exercises were different from the remaining exercises only (p#0.05).
§For triceps brachii, these exercises were not different from each other but were
significantly greater than the remaining exercises (p#0.05).
TABLE 3. Normalized muscle activity (% maximal
voluntary isometric contraction) from the lower body
muscles during the exercises performed in this
study.*†
Exercise VL BF
Swiss ball rolls 83.6 644.2‡53.6 627.9‡
Swiss ball hip
extension
27.1 613.2§ 20.6 612.9§
Swiss ball praying
mantis
25.3 68.5§ 10.6 64.6
k
Swiss ball single
leg squat
22.2 611.2§ 3.6 65.5
Prone hold 11.2 66.4 2.2 61.0
Swiss Ball hold
and crunch
8.1 66.9 2.1 60.8
Swiss ball bridge 3.1 65.8 5.6 65.7
*VL = vastus lateralis; BF = biceps femoris
†Values reported are mean 6SD.
‡For VL and BF, the Swiss ball roll had significantly
higher activity compared to all other exercises (p#0.05).
§For VL, these exercises were not different from each
other but were greater than the remaining exercises. For
BF, this exercise was different from all remaining exercises
(p#0.05).
k
For BF, this exercise was different from the remaining
exercises only (p#0.05).
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passive skeletal structures, and the central nervous system as
the control unit (34,35). This study presents the acute muscle
activity levels in an isolated session only. Therefore, indivi-
duals should not assume what the effects of performing the
type of exercise measured in this study may be on malada-
ptive core muscle recruitment patterns, or strength and
endurance characteristics, until appropriate training studies
are performed.
We have found limited support for our experimental
hypotheses that all the advanced Swiss ball exercises tested
here would elicit muscle activity levels commensurate with
recommendations for a strength training effect. The majority
of exercises studied do not differ appreciably to the intensity
levels described for Swiss ball exercises in previous literature,
which are of a low to moderate level. Furthermore, there was
little evidence presented in this study to suggest that advanced
Swiss ball exercises can elicit greater trunk, upper body, or
lower body muscle activity levels than moderately loaded
conventional resistance exercises such as the bench press,
squat, and deadlift (11,18,20,32). The Swiss ball roll move-
ment clearly stands out as a significantly difficult exercise
with potential to elicit strength training effects. Activity levels
of 83.6 644.2% for VL and 72.5 633.4% for TB indicate that
this exercise is at an appropriate intensity for these muscles,
which may elicit strength effects in advanced trainers (36,37).
The highest recorded erector spinae activity (54.3 628.7%)
was also measured during the roll exercise. Remaining upper,
lower, and abdominal muscle activity during the roll exercise
ranged from 30 to 55%. This indicates that for most indivi-
duals, a higher number of repetitions of the Swiss ball roll
exercise might be able to elicit endurance adaptations (12),
whereas for some untrained individuals, this exercise may be
appropriate as a strength training stimulus for multiple muscles.
Resistance exercises stressing multiple muscle groups have
been shown to elicit the greatest acute metabolic response
(8,38,41). Increased metabolic demand is an important factor
for the adaptations in muscle associated with strength and
endurance. Therefore, the Swiss ball roll appears to be the
most likely exercise from the current study to apply and
investigate in clinical and research contexts for significant
muscular adaptation.
It is surprising given the widespread advocacy of Swiss ball
exercises as providing a significant abdominal stimulus that
apart from the bridge none of these advanced exercises had
levels of activity where one could reasonably justify pre-
scribing them for a trunk or ‘‘core’’ strengthening program.
The Swiss ball bridge had RA activity at an approximate level
for strength training in untrained individuals and possibly
some more advanced trainers (61.3 628.5%). The results
from this study are commensurate with those of previous
research, which is yet to identify any Swiss ball exercise as
being able to elicit trunk muscle activity in the range of
a strength training stimulus (15,17,24,27,28,32). Although
there are probably more difficult Swiss ball exercises that
could be performed to elicit higher trunk muscle activity
levels, the complexity of the movements begins to make this
exercise modality unfeasible for the majority of individuals,
especially when greater trunk muscle activity levels can be
achieved using relatively basic, moderately loaded resistance
exercises such as the squat and deadlift. Support for basic
resistance exercise movements eliciting high levels of trunk
muscle activity has also been provided with recent evidence
showing that maximal isometric shoulder movements, such
as bilateral shoulder extension, elicit trunk muscle activity
levels greater than performing maximal isolated trunk exert-
ions (40). The Swiss ball roll, although obviously providing
the highest overall muscle activity for the body, was the
most complicated movement to teach. Although no acute
accidents happened during testing, the likelihood of an in-
cident occurring with the use of an unstable Swiss ball during
complex whole-body exercises, or an injury from prolonged
exposure to this type of difficult movement, cannot be dis-
counted. This raises the issue for the practicality of prescrib-
ing Swiss ball exercises, when the majority of research is
providing a case against its use as a beneficial training surface.
Recent intervention studies have not found significant
positive evidence to recommend use of the Swiss ball over
other modalities of exercise. Stanton recently found that a
6-week Swiss ball training program did not significantly
improve running fitness, economy, or posture, compared with
previous research the author cited using conventional
resistance training, which positively influences these variables
(39). A study that randomized individuals with chronic low
back pain to either supervised Swiss ball exercise or an
unsupervised control exercise advice group (no Swiss ball
exercise) found no difference between interventions for
changes in primary disability and pain outcome measures
at the long-term follow-up (30,31). Other research has
investigated the Swiss ball as a support surface during
resistance exercises and shown little practical use. Some
research has found reductions in maximal isometric force
output using a Swiss ball as a support surface (4,10), whereas
other research has found no changes in prime mover muscle
activity during the bench press (20,29). In conclusion, this
study has provided little evidence to support the hypothesis
that advanced Swiss ball exercises can elicit muscle activity
commensurate with recommendations for strength training.
PRACTICAL APPLICATIONS
This is the first study we know of to measure muscle activity
during more advanced Swiss ball exercises that are observed
in the recreational training environment. If the goal of
strength and conditioning coaches is to increase the strength
of the upper body, lower body, or trunk musculature, it seems
that advanced Swiss ball exercises will be no more beneficial
than moderately loaded resistance exercises. Moreover, the
only Swiss ball exercise to achieve a high level of muscle
activity was the most complicated movement to perform.
When compared with relatively basic to teach and perform
resistance exercises such as shoulder extensions, squats, and
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deadlifts, the use of a Swiss ball seems redundant. Addition-
ally, the benefit of conventional resistance training is that
increasing the external load will increase the activity of muscle
groups of interest, while allowing for periodization and
progression of the training dose over time, whereas a Swiss
ball based program appears to require more complex and
difficult movements for ongoing progression. Advanced Swiss
ball exercises should be considered a novelty movement that
could be introduced in small amounts to alleviate staleness
with long-term training. Coaches should be advised to learn,
and then prescribe, large conventional multijoint exercises for
the greater benefits they provide rather than use complicated
circus like movements on a Swiss ball. It must be considered
that the practical difficulty and potential risks involved with
performing an advanced Swiss ball exercise, such as the roll in
this study, or standing on a Swiss ball with weights as
observed in some recreational trainers, probably outweigh
any benefits.
ACKNOWLEDGMENTS
The authors have no professional relationships with any
company or manufacturer who may benefit from the results of
the current study. The results of the current study do not
constitute endorsement of the product used by the authors or
the National Strength & Conditioning Association.
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