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Bilateral Differences in Anthropometric Measurements and Isokinetic Strength
Variables of Female University Netball Players
Kyra-Kezzia Duvenage, Yolandi Willemse and J Hans De Ridder*
Physical Activity, Sport and Recreation Focus Area (PhASRec), Faculty of Health Sciences, South Africa
Submission:April 22, 2021; Published:May 03, 2021
*Corresponding author:J Hans de Ridder, Physical Activity, Sport and Recreation Focus Area (PhASRec), Faculty of Health Sciences, North-West University, Potchefstroom, 2520, South Africa
How to cite this article:Kyra-Kezzia D, Yolandi W, J Hans De R. Bilateral Differences in Anthropometric Measurements and Isokinetic Strength Variables
of Female University Netball Players. J Phy Fit Treatment & Sports. 2021; 9(1): 555752. DOI: 10.19080/JPFMTS.2021.09.555752
Background: The unilateral demands on the dominant (D) limbs in netball players, may lead to developments and changes that differs from that of the non-dominant (ND) limbs. An individual who is constantly exposed to unilateral movements or repeated use of the D limb, can also develop bilateral differences between the D and ND limbs. The purpose of the study was to determine if any significant bilateral differences in anthropometric and isokinetic strength measurements occurred between the D and ND limbs of the upper and lower parts of the body in female university netball players.
Methods: 44 female university-level netball players (age: 20.02±1.39 years) of a prominent university in the North-West Province in South Africa, participated in this study. A total of 25 anthropometric measurements were taken and bilateral isokinetic muscle strength was also tested. Technical error of measurement (TEM) (only for the anthropometrical measurements) and Confidence Interval (CI) at 90% were calculated. Dependent t-tests were done to determine bilateral differences between the D and ND sides of the upper and lower limbs. Effect sizes (ES) were calculated with Cohen’s effect size (d=0.8) to determine practical significance.
Results: To support the first objective of this study, results obtained from the biceps skinfold (-17.93±28.85%), showed the only significant level of asymmetry with statistical and practical significance differences of p<0.00 (d=0.34). To sustenance the second objective of this study, results obtained from the knee and shoulder isokinetic strength tests revealed no statistical nor practical significant differences between D and ND isokinetic knee strength (p<0.48; d=0.1). In contrast to the previous mentioned, the shoulder flexion/extension measurements showed statistical (p<0.02) and practical (d=0.28) significant differences between the D and ND side. The shoulder extensor revealed stronger statistical and practical significant differences (p<0.00; d=0.44) than the shoulder flexors (p<0.01; d=0.29).
Conclusion: The results of this study, revealed that netball players tend to develop marginal bilateral differences between D and ND limbs in response to the demands of the sport and the unilateral movements. Thus, the researcher concludes that university-level netball players showed more differences between the D and ND side in the upper body than the lower body.
In many cases, when comparing unilateral tasks, some level of functional asymmetry will be present . Functional asymmetry leads to bilateral differences. This is due to actions in which one side of the body is continuously used . According to Pirnay et al. [3,4], the unilateral demands on the dominant (D) limbs leads to development and changes in body composition that differs from that of the non-dominant (ND) side. Unilateral movements such as running, changing direction, repetitive jumps, landing and passing
are required of a netball player [5,6]. During these unilateral movements, power is generated by an individual limb, whereas both limbs are used during bilateral movements . Elevation from, or landing on one leg during a rebound, or throwing an object with one arm is considered as a unilateral movement .
An individual who is constantly exposed to unilateral movements or repeated use of the D limb can develop bilateral differences between D and ND limbs [1, 9, 10]. It is therefore important to investigate the changes in bilateral differences
between D and ND limbs . Furthermore, what is known as
anthropometric asymmetry (bilateral difference) is often found in
participants in sport requiring unilateral movements, for example,
tennis [3,12], javelin  and fast bowling in cricket [14,15]. The
importance of studies on athletes with bilateral differences is
emphasized by the negative consequences thereof, for example
unilateral training and movements have a negative influence
on range of motion and optimal performance . Unilateral
movements in netball may vary from player to player due to the
demands of the position and the nature usually depends on their
Research in sporting codes that predominantly use
movements from unilateral base support, noted that adaptation
to certain anthropometrical measurements occurs. Upper limb
dominance (stronger hand when performing certain tasks such as
passing the ball) has a positive link to the hypertrophy of the distal
humerus of inactive female subjects. The epicondyle breadth
accurately reflects handiness (dominance) in 68% of cases, where
the D epicondyle breadth is larger than that of the ND side .
The results showed statistically significant bilateral differences
(p<0.001) between left- and right-handed test subjects, and
therefore appeared to reflect a positive relationship regarding the
direction of asymmetry and an individual’s D limb . In football
players, the lower limbs showed a positive correlation (r=0.31-
0.41) between kicking performance and lean mass values [19-
21]. A positive correlation was found between the lean mass of
the upper leg and kicking accuracy (Kicking limb: r=-0.43 to -0.59;
Support limb: r=-0.53 to -0.59).
To measure the isokinetic strength of a contracting muscle,
an isokinetic dynamometer can be used [22,23]. This is a reliable
and objective method to measure muscle strength and bilateral
strength differences in limbs [22,24,25]. It is recommended that
bilateral strength differences should be less than 10-15% between
the D and ND limb. A larger difference between D and ND limbs may
influence performance negatively [10,26-28]. Regarding bilateral
strength ratios between the agonist and antagonist muscle,
several studies reported a ratio percentage of 50-80% to be an
acceptable value [9,29,30]. Although no consensus could be found
on the agonist and agonist ratio for the lower limbs, the general
acceptance percentage for muscle ratio is 60%, dependent on the
different testing velocities, but there seems to be no difference
between gender or choice of sport [31,32].
Kong and Burns  concluded that the knee FLX:EXT
differences, with a higher ratio on the D leg, can be attributed
to the stronger knee flexor muscles in the D leg, while the knee
extensor muscles was mostly similar for both legs, and explained
that this difference is due to the different training background of
the participants. Chan et al.  stated that the shoulder flexion/
extension percentage ratios (FLX:EXT) measure between 75%
and 85%, but it is noted in a study of Perrin  that overhead
sport tends to achieve a percentage ratio of only 50%. Researchers
stated that bilateral differences in the shoulder were due to the
D shoulder developing a systematic superiority in overall muscle
strength over years of training .
Since no recent studies on netball players’ shoulder flexion/
extension isokinetic testing were available, a gap was found in the
knowledge of bilateral differences in the upper limbs. The present
study will provide a guideline for these professionals regarding
scientifically formulated training programmed for preventing
bilateral differences in netball players. The purposes of this
article are therefore: 1.) to determine if university level netball
players show significant presence of bilateral differences in the
upper and lower body, and if so, 2.) which of the anthropometric
measurements (skinfolds, girths, breadths and/or lengths) and
isokinetic strength variables show the greatest degree of bilateral
differences between the D and ND limbs.
This study made use of an experimental test design with
convenience sampling. Forty-four female netball players (N=44),
from the North-West University in South Africa, with an average
age of 20.2±1.4 years, were tested. The participants had an average
stature of 175.7±7.2cm and an average body mass of 72.5±8.8kg.
The players were tested during the in-season phase of their
periodization cycle. Risks for these participants were minimal and
all monitoring and safety measurements were in place.
Before data collection, a project letter was sent to the
university’s department of sport, coaches, and managers,
explaining the purpose of the study, and seeking permission.
Approval was given by all relevant role players. Ethical approval
for this study was obtained from the Human Research Ethics
Committee of the Faculty of Health Science at North-West
University in South Africa (NWU-00359-15-A1). Only players who
provided voluntary consent, and complied with the inclusion and
exclusion criteria, could participate in this study.
Anthropometric measurements were taken early in the
morning, before breakfast or training. Measurements were taken
according to the protocol of the International Society for the
Advancement of Kinanthropometry (ISAK) . A total of 25
anthropometric measurements were taken. Stature, body mass,
eight skinfolds, six girths, five segment lengths and four bone
breadths were measured on both the dominant (D) and the nondominant
(ND) side. All measurements were taken twice, with a
third measurement when any of the first 2 measurements were
outside the allowed limits . In case of 2 measurements, the mean value was used as the official reading whereas the median
was used in the case of three measurements. Under ISAK protocol,
the subjects were requested to present themselves in the
appropriate clothing for measurements to be made as effective as
Body mass was measured on a calibrated electronic scale
(precision, A&D Company, Saitama, Japan) to the nearest 0.1 kg.
Stretch stature was measured with a Seca213 stadiometer (Seca
equipment, Hamburg, Germany) to the nearest 0.1 cm. Skinfolds
(mm) were measured to the nearest 0.1 mm on eight different sites,
namely the triceps, biceps, subscapular, iliac crest, supraspinale,
abdominal, thigh and calf . A Tradicional Scientific Skinfold
Caliper (10g.mm-2) (Cescorf Equipment, Porto Alegre, Brazil)
were used to measure skinfolds. Breadths (cm) were determined
at four different sites, namely the femur, humerus, wrist and ankle
breadths . A bone caliper (Cescorf Equipment, Porto Alegre,
Brazil) was used to measure the breadths to the nearest 0.1 cm.
About the girths, five girths were measured. The relaxed upper
arm, flexed upper arm, forearm-, mid-thigh- and calf. Girths were
measured, using a flexible steel tape (Cescorf Equipment, Porto
Alegre, Brazil) to the nearest 0.1cm .
A total of five lengths were measured. The upper arm,
forearm, hand, upper leg, and lower leg. Lengths were measured
using a segmometer (Cescorf Equipment, Porto Alegre, Brazil)
to the nearest 0.1cm . For the sum of the six skinfolds (Σ6
skinfolds) the triceps, subscapular, supraspinale, abdominal, thigh
and calf skinfolds were used. Body fat percentages were obtained
by means of the equation of Withers et al. . The equations of
Lee et al.  and Martin  were use respectively to calculate
Muscle Mass and Skeleton Mass.
The technical error of measurement (TEM) was calculated
[40,41]. An intra-tester TEM of 5-7.5% relative TEM values are
considered as acceptable for skinfolds and 1-1.5% for the other
anthropometrical measurements . The relative TEM scores for
this study showed less than 5.75%,1.14%, 0.89% and 1.69% for
the skinfolds, girths, lengths as well as the breadths, respectively.
Limb dominance was determined to compare the D side with
the ND side to be able to investigate the bilateral differences. Limb
dominance was determined by self-declaration for the upper and
lower limb. Coren and Porac  reported that self-declaration
was found to have a 97.7% agreement with task performance
(kicking a ball) and a 96% test-retest agreement. Blackburn
and Knüsel  stated that previous studies have linked selfprofessed
(stronger hand when performing a certain task such as
throwing a ball) for the upper limbs with the hypertrophy of the
An isokinetic dynamometer (Cybex NormTM,)  was used
for testing bilateral isokinetic muscle strength. Software used was
the Humac 2014 and the Cybex was calibrated before each testing
session. The calibration was done by the described protocol .
The testing consisted of knee flexion and extension [25,44,45] and
a shoulder flexion and extension (supine) protocol. Both tests were
done at a speed of 60°/sec for concentric movement . Before
the isokinetic strength tests, each player performed a warm-up
session. All participants followed the same order of testing by
starting with the lower limbs. The warm-up for the lower limbs
consisted of five minutes cycling on a stationary ergometer on
low intensity (75 Watts) , and specific dynamic stretches .
The upper body warm-up consisted of two minutes’ sub-maximal
intensity rowing on an upper-body ergometer , and specific
dynamic stretches for the upper limbs .
Each netball player was being positioned according to the
directions of the specific protocol  for the different joints that
were tested. A familiarization set was done before the formal test
of the knee and shoulder. This familiarization consisted of two (2)
submaximal concentric contractions, after which the player rested
for 60 seconds . This was followed by the maximal concentric
contraction test, which consists of five repetitions for the knee
flexion-extension [25,44,45] and shoulder flexion-extension 
at the velocity of 60°/sec.
The Statistical Data Processing package (IBM SPSS Statistics
Version 25)  was used to determine descriptive statistics, as
well as 90% confidence intervals (CI)). Due to the small sample
size, the statistically significant difference of all measurements
between the D and ND sides were performed using a dependent
t-test (p≤0.05). Effect size (ES) were also calculated for the total
group (D and ND of the upper and lower limbs) (d =” “ “M1-M2 “
/”s”), and Cohen’s effect size for practical significance was used,
as reported by Ellis and Steyn . Cohens’s effect size (ES) were
interpreted as follow: high practical significance, d≥0.8*; medium
practical significance, d≥0.5; low practical significance, d≥0.2.
The 90% CI was qualitatively interpreted using the following
thresholds: <0.19, trivial; 0.2-0.59, small; 0.6-1.19, medium; 1.2-
1.99, large; 2.0-4.0, very large; >4, vast differences to determine
the likelihood that the true value of the effect represents
substantially beneficial or detrimental changes [54-60]. The
smallest practically meaningful effect was considered 0.2 either
positive or negative with values implicating either the D (positive)
or the ND (negative) side. Effects where the CI overlapped, small
positive or small negative effects were defined as unclear. Effect
sizes could be beneficial/detrimental were either positive or
negative medium to vast differences, with either the upper or
lower limit of the 90% CI not exceeding a trivial ES (<0.19) on
Descriptive statistics for the anthropometric variables are
presented in Table 1. When comparing the mean scores from Table
1, the extent of bilateral differences between the dominant (D)
and the non-dominant (ND) sides, are evenly distributed for all
the skinfolds. It can be noted that the data shows a large variance
between the minimum and maximum values for skinfolds as
well as girth measurements between D an ND. This is due to the
small sample size of the netball players in the different playing
positions. Different fitness and competition levels of the players
that trained and participated in different divisions at university
level, also had an influence on the anthropometric measurements.
Table 1 represents statistical and practical significant anthropometrical
differences between the D and ND sides. About the skinfolds,
the biceps, triceps, and abdominal skinfolds showed both
statistical as well as practical significant differences between
the D and ND sides. The triceps and abdominal skinfolds had
smaller measurements on the ND side, with the biceps showing a
larger skinfold on the ND side. Although the subscapular skinfold
showed no statistical significance, a practical significance difference
between the D and ND side was found with the D skinfold
the smaller value.
In relation to the girth measurements, only two of these
measurements, flexed upper arm and forearm, showed statistical
as well as practical significant differences. The relaxed upper arm
and mid-thigh showed only statistically significant differences
between the two sides. About all the girths, the girths on the D
side were larger than those on the ND side. Although all the length
measurements on the ND side surpass those on the D side, the
radial-stylion (forearm) length was the only measurement with a
statistically significant difference as well as a practical significant
difference between D and ND. For the breadths, the wrist and
femur breadths had statistically significant differences between
the D and ND, with both these measurements having larger values
on the D side.
Regarding the differences in body composition, the sum of
six skinfolds (mm), body fat percentage (%) and muscle mass
(kg) showed statistically significant differences between D and
ND. Muscle mass also showed a practical significant difference
between the D and ND sides. About all four the body composition
measurements, the D sides showed larger values than that of the
ND side. In Table 1, the results depict the mean differences (MD)
between the D and ND sides and the 90% CI for the effect size
(ES) of the upper and lower limits of each of the variables that
did not indicate trivial to unclear ES in the measurements. From
the obtained results of all measured variables: biceps skinfold
(MD -1.88: -2.71 and -1.05), subscapular skinfolds (MD -0.65;
-1.29 and -0.01), forearm length (MD -0.38; -0.59 and -0.18), and
lower leg length (MD -0.21; -0.46 and 0.03), attained small to very
large worthwhile effect in favour of the ND side. In this regard, the
ND side measurements exceeded that of the D side. Furthermore,
triceps skinfolds (MD 1.01; 0.31 and 1.70), supraspinale skinfold
(MD 0.51; -0.04 and 1.06), abdominal skinfold (MD 1.25; 0.82
and 1.67), body fat percentage (MD 0.38; 0.19 and 0.58), and
muscle mass (MD 0.76; 0.49 and 1.03) attained small to medium
worthwhile effect in favour of the D side.
About the girths, the calf girth (MD 0.11; -0.02 and 0.24),
relaxed upper arm (MD 0.19; 0.04 and 0.34), flexed upper arm
(MD 0.34; 0.17 and 0.51), forearm girth (MD 0.48; 0.38 and 0.58)
and thigh girth (MD 0.38; 0.11 and 0.66)] resulted in a small to
medium worthwhile effect in favour of the D side. Only sum of 6
skinfolds (MD 2.40; 1.18 and 3.63) showed medium to very large
worthwhile effect in favour of the D side. All other obtained results
are considered unclear due to CI upper and lower limit exceeding
the smallest positive and smallest negative effect of 0.2.
Descriptive statistics for the isokinetic measurements used in
this study are presented in Table 2.
The entire group of university-level netball players showed a
mean peak torque (PT) of 164.95±28.36Nm and 106.93±23.9Nm
for knee extensor and flexor strength respectively with regards to
the D limb. Values of 163.91±26.74Nm and 109.32±18.05Nm were
recorded respectively for the ND limb. Where results were normalised
for total body weight (TBW), the group had a mean TBW
of 2.28±0.38Nm/kg for knee extensor strength and 1.52±0.27Nm/
kg for knee flexor strength of the D limb. The ND limb revealed
a mean TBW in knee extensor strength of 2.27±0.39Nm/kg and
1.51±0.24Nm/kg for knee flexor strength.
The knee FLX:EXT revealed an average percentage ratio of
66.75±8.36% for the D limb and 67.68±12.68% for the ND limb.
The knee flexor PT and the knee FLX:EXT ratio showed higher
values for the ND side, whereas the knee extensor PT, normalised
for body weight extensor PT and normalised for body weight flexor
PT values, presented higher values for the D side. Knee extensors
showed an average of 9.39±7.63% deficit, where the D knee had
higher mean PT values. The knee flexors resulted in 9.73±6.24%
deficit, with the ND knee having higher mean PT values.
Regarding the upper limbs, the shoulder extension/flexion
isokinetic test results revealed that the shoulder extensor
and flexor mean PT were 63.0±8.38Nm and 44.45±7.35Nm
respectively for the D limb and 59.27±7.67Nm and 42.32±6.12Nm
for the ND limb. Normalized for total body weight, the group
showed a mean PT for the extensors and flexors of 0.87±0.11Nm/
kg and 0.62±0.10Nm/kg for the D limb respectively. The ND limb
showed a mean PT value of 0.82±0.11Nm/kg for the extensors
and 0.59±0.09Nm/kg for the flexors, respectively.
Regarding the shoulder FLX:EXT, an average of 71.23±11.10%
for the D limb and 72.32±11.21% for the ND limb were recorded.
The shoulder extension means PT, normalized for body weight
extension PT, shoulder flexion mean PT and normalized for
body weight flexion PT values, resulted in higher values for
the D side. The shoulder FLX: EXT percentage ratio had higher
values for the ND side. For the shoulder extension/flexion test,
the bilateral differences for the extensor and flexors showed an
average percentage of 8.68±6.55% deficit and 9.18±7.04% deficit
respectively where the D shoulder had the greater mean PT values
on both sides.
Table 2 represents the statistical and practical significant
bilateral differences for the knee and shoulder extension/
flexion tests at a testing velocity of 60°/sec. In Table 2, none of
the isokinetic knee extension/flexion measurements showed
statistical or practical significant differences between the D and ND
sides (p<0.48). In contrast to this, the shoulder flexion/extension
measurements showed a statistical (p<0.02) and practical
(d=0.28) significant difference between the D and ND sides; the
shoulder extensor variable showed a stronger statistical and
practical significant difference (p<0.00; d=0.44) than the shoulder
flexors (p<0.01; d=0.29). The shoulder FLX:EXT percentage ratio
showed no statistical or practical significant difference between
the D and ND side (p<0.55; d=0.10).
The 90% CI of the difference, depict the mean differences
between the D and ND sides size and the 90% CI for effect size
(ES) upper and lower limits of each of the variables that did
not indicate trivial to an unclear ES of measurements. From the
results obtained, the shoulder extensor PT (MD 3.73; 2.07 and
5.38), shoulder extensor TBW (MD 4.91; 2.71 and 7.10), shoulder
flexor PT (MD 2.14; 0.86 and 3.41) and shoulder flexor TBW (MD
2.75; 0.91 and 4.59), presented medium to vast difference with a
worthwhile effect size in favour of the D side. All other obtained
results were considered unclear due to CI upper and lower limit
exceeding the smallest positive and smallest negative effect of 0.2.
No statistical and practical significant differences were found
in the knee extension/flexion isokinetic strength test, which is in
correspondence with Kobayashi et al. , who tested healthy
male subjects. In the last-mentioned study, the researchers found no statistical differences between the D and ND lower limbs
regarding the knee extensors and flexors (p<0.25 and p<0.39
respectively), with only a small practical significant difference
(d=0.22 and d=0.26 respectively) at a testing velocity 60°/sec. In
this study the bilateral differences were less than 10% between
the D and ND lower body, indicating that the netball players
in this study had well muscle balance that was in line with the
recommendations given in the literature [10,26-28].
About the anthropometric data, it is evident that the biceps
skinfolds had the highest extent of bilateral differences and
showed statistical and practical significant differences between
the D and ND sides of the upper limbs. A smaller biceps skinfold
on the D side may have a positive effect on performance 
since players with a higher muscle mass and lower body fat mass
perform better than players with a lower muscle mass and a
higher body fat mass . The biceps skinfold bilateral differences
may be present due to the use of the D arm during the one-handed
overhead and shoulder pass which is frequently used [57,58]. This
study showed statistically significant differences between the D
and ND side for the sum of six skinfolds, bone density, body fat
percentage, and muscle mass. The sum of six skinfolds and body
fat percentage was in favour of the ND side; the measurements
were smaller on the ND side than the D side which has a better
outcome in performance . Only muscle mass showed a small
practical significant difference between the D and ND sides.
Muscle mass was in favour of the D side, where the muscle
mass results were larger than on the ND side. These findings
correspond to those of the study of Krzykaɫa and Leszczyński ,
which found statistically significant differences between the left
and right side of the body for muscle mass and fat mass of female
hockey players where the left side had the larger measurements.
The bilateral differences in muscle mass can be caused by the side
preferences in unilateral movement and the demands of a netball
match. A better understanding of the mechanism of the bilateral
difference and the effect on performance will enable a more
targeted approach to specific training [20,21].
About the Isokinetic measurements, the study of Kobayashi
et al.  contradicts other studies [30,61-63] with regards to
the knee extension/flexion isokinetic strength test. Statistically
significant differences (p<0.001) were found between the D and
ND lower limbs in the knee extension/flexion isokinetic test of
female Swedish test subjects , male and female recreationally
active athletes , random selected test subjects of different
age groups and gender , as well as in cadet basketball players
. The knee FLX: EXT percentage ratio of the netball players
was 66.75±8.36% for the D knee and 67.68±12.68% for the ND
knee, which falls within the acceptable range between 50-80% at
a testing velocity of 60°/sec [9,29,30]. We attribute these findings
to the specific strength training programmed and court training
of these netball players partaking in which involved unilateral
as well as bilateral movements, or to the various passing and
landing movements throughout netball training or a match. This
further showed that the netball players from our study were in
a well-balanced condition concerning their lower limb bilateral
differences and FLX:EXT muscular balance.
Even though the netball players showed statistical and
practical significance about isokinetic strength, bilateral
differences between the D and ND sides for the shoulder flexion/
extension test, the D shoulder had greater values than the ND
shoulder. The reason for this could be due to the asymmetric
nature of shoulder movements in overhead throwing sport codes
, where this relates to studies done on the isokinetic shoulder
internal/external rotation test. Although limited studies were
found on isokinetic strength for the shoulder flexion/extension
movement, studies were included in the literature review that
investigated isokinetic strength for the shoulder internal/external
In a study done on elite female handball players, researchers
found that the players showed statistically significant differences
between the D and ND shoulder for internal/external rotation
(p<0.05) . These findings correspond with the results of
Markou and Vagenas , who found statistically significant
differences (p<0.001) between the D and ND sides for the
shoulder internal-external rotation strength test in elite male
volleyball players. Both above-mentioned studies showed that the
D shoulder achieved higher values than the ND shoulder [35,65].
Regarding shoulder FLX:EXT ratio, these netball players had a
ratio of 71.23±11.10% for the D shoulder and 72.32±11.21% for
the ND shoulder. These finding are like the shoulder FLX:EXT ratio
of Berg et al. , who indicated that 81% and 77% for the left
and right shoulders respectively (dominance was not recorded) at
a testing velocity of 60°/sec.
Bilateral differences observed for both the upper and lower
body, were less than the 10-15% of that recommended by
various researchers [10,26,28]. This may be due to the unilateral
movements in various sporting codes [9,11]. The reason for the
bilateral differences being larger in the upper body than in the
lower body, may be since the upper body is more exposed to
unilateral movement in netball as well as upper body dominance
and daily activity demands [9,11].
In conclusion, these findings support the hypothesis, that
netball players tend to develop bilateral differences between D and
ND limbs. Sporting codes other than netball, that predominantly
use unilateral movements, differ significantly between the D and
ND limbs concerning different anthropometrical measurements.
Research has found statistically significant bilateral differences
for some anthropometrical variables of various sporting codes
predominantly using unilateral movements. Regarding the
anthropometric measurements, it might have been predicted from previous research that a unilateral sport code, such as netball,
would have greater differences in bilateral measurements. The
results of this study partially confirm this. The Biceps skinfold and
muscle mass, showed statistical and practical significance were
as the sum of skinfolds, bone density and body fat percentage
showed statistically significant difference but not practical.
For the isokinetic strength, only the upper body showed
statistical and practical significant difference, where the D
surpassed the ND upper limb’s variables. These findings are due
to the demands of the netball and its unilateral movements such
as repeated passing action on the D side during netball games.
Thus, we conclude that university-level netball players showed
significant differences between the D and ND side in the upper
body. Training programs could be developed specifically for the
needs of these netball players and implemented appropriately,
firstly to prevent, and secondly to remedy the occurrence of
such bilateral differences. In the end, this will improve their
performance and help with the conditioning of these players. A
better understanding of the mechanism of the bilateral difference
will enable a more targeted approach to training.
The study provides significant insight into the field of study for
university-level netball players concerning bilateral differences.
However, it has certain shortcomings that need to be addressed
and taken into consideration when interpreting the results:
i. Firstly, the sample size could also have been larger for
more validity in the study, which can therefore not be generalized
to the whole of the country or the world. It is recommended that
different university sites be included in future studies for the
better demographic representation of South Africa.
ii. Secondly, only two joints were tested for isokinetic
strength to determine bilateral differences. It is recommended
that more isokinetic strength tests over different joints, such as
the wrist, ankle, and hip, could be included in the research design
so that more information can be obtained about the bilateral
difference development in netball players.
iii. Thirdly, different playing levels and positions have
different training programmed and schedules. Investigating the
effect of different playing levels and/or positions may give a good
indication of bilateral development of the D versus the ND limbs.
Lastly, the rotator cuff muscle, which is primarily involved in
the passing mechanism (although the netball passing mechanism
differs from other passing) may also give a good indication of
bilateral development of the D versus the ND shoulder. Future
studies can take these recommendations into account.
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