Journal of Hand Therapy xxx (2017) 1e8
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Journal of Hand Therapy
journal homepage: www.jhandtherapy.org
Scientific/Clinical Article
Hand grip strength and dexterity function in children aged 6-12
years: A cross-sectional study
Mohammed T.A. Omar PhD, PT a, b, *, Ahmad H. Alghadir PhD, PT b, Hamayun Zafar PhD, PT b, c,
Shaheerah Al Baker BSc, PT d
a
Department of Physical Therapy for Surgery, Faculty of Physical Therapy, Cairo University, Giza, Egypt
Department of Rehabilitation Health Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
c
Department of Odontology, Clinical Oral Physiology, Faculty of Medicine, Umeå University, Umeå, Sweden
d
Physical Therapy Department, King Saud Medical City, Riyadh, Saudi Arabia
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 12 December 2015
Received in revised form
11 January 2017
Accepted 6 February 2017
Available online xxx
Study Design: Cross-sectional and clinical measurement.
Introduction: Assessment of hand function considers an essential part in clinical practice.
Purpose of the Study: To develop normative values of hand grip strength and dexterity function for 6-12year-old children in Saudi Arabia.
Methods: Grip strength and dexterity function was measured in 525 children using Grip Track hand
dynamometer (JTECH Medical, Midvale, UT, USA) and 9-hole pegboard test respectively.
Results: The grip strength and dexterity function was improved as age progressed regardless of gender.
Across all age groups, the hand grip strength of boys was significantly higher than girls for dominant
hand (31.75 10.33 vs 28.24 9.35; P < .001) and nondominant hand (31.01 10.27 vs 27.27 9.30; P
< .001). The girls performed slightly faster than boys for dominant hand (19.70 vs 20.68; P < .05) and
nondominant hand (21.79 vs 23.46; P < .05). In general, girls completed a 9-HPT faster than boys in the 2
of 7 age groups: 11 years (9-HPT scores ¼ 2.10 seconds; P < .01) and 12 years (9-HPT scores ¼ 1.93
seconds; P < .01).
Discussion: The overall patterns of hand grip strength and dexterity function observed in the present
study are similar to the previous studies that established acceleration of grip strength with advanced age,
and faster performance scores in older children than younger children in both genders.
Conclusions: Norms of hand grip strength and dexterity enable therapists to identify some developmental
characteristics of hand function among Saudi children, determine the presence of impairment, and
compare scores from children in different clinical settings.
Level of Evidence: Not applicable.
Ó 2017 Hanley & Belfus, an imprint of Elsevier Inc. All rights reserved.
Keywords:
Hand strength
Dexterity function
Children
Introduction
Hands are the most effective means of communication and
performing the complex tasks of daily living activities (eg, eating,
grooming, and bathing). Work activities as well as play and leisure
Conflict of interest: All named authors hereby declare that they have no conflicts
of interest to disclose. The authors alone are responsible for the content and writing
of the article.
The authors extend their sincere appreciation to the Deanship of Scientific
Research at King Saud University for funding this research through the research
group no. RGP-VPP-209.
* Corresponding author. Department of Rehabilitation Sciences, College of
Applied Medical Sciences, King Saud University, P.O. Box 10219, Riyadh 11433, Saudi
Arabia. Tel.: þ966 542 115404.
E-mail addresses: dr.taher_m@yahoo.com, momarar@cu.edu.eg, momarar@
ksu.edu.sa (M.T.A. Omar).
activities require both grip strength and manual dexterity.1-3
Moreover, 60% of school activities require fine motor and manual
dexterity skills.4 Therefore, the assessment of hand function is an
essential part of physical and occupational therapy evaluation for
children with a range of disorders, such as trauma, congenital, and
neurologic disorders. Normal data on hand grip strength and
manual dexterity are important to identify the developmental level
and degree of disability; determine efficacy of rehabilitation and
assess the integrity of upper limb functions; and compare scores
from typical and atypical children according to the age, gender,
race/ethnicity, and body measures.1-3,5,6
A few studies have been published on measurement of manual
dexterity of the hand in children.7-11 Smith et al7 and Yim et al8
published a normative data of hand dexterity using the 9-hole
peg test (9-HPT) for children aged 5-10 and 7-12 years, respectively. Furthermore, Poole et al9 measured manual dexterity in
0894-1130/$ e see front matter Ó 2017 Hanley & Belfus, an imprint of Elsevier Inc. All rights reserved.
http://dx.doi.org/10.1016/j.jht.2017.02.004
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M.T.A. Omar et al. / Journal of Hand Therapy xxx (2017) 1e8
children aged 4-19 years using 9-HPT. The authors proposed that
the 9-HPT may be an appropriate screening tool because it reflects
multiple aspects of motor control, such as preshaping the hand,
grasping, moving, and releasing the object.8,9 However, this manual
screening test is not routinely performed for children to detect their
dexterity level, and there is no report on the normative values
among Saudi children.
Several studies have reported norms of hand grip strength in
children.8,12-27 The most recent studies provided data from children
in Sweden,20 Korea,8 The Netherlands,21 the United States,22
Spain,23 England,24 and Canada.25 Earlier studies were from
children in the United States13,15,17,18 and Australia.14,16 A thorough
review of these studies suggests a decreased grip strength over the
past 3 decades and concluded that hand functions (eg, grip strength
and manual dexterity) might be changed over generations and
across countries.20-25 Thus, establishing the norms of hand grip
strength and manual dexterity for each geographic region is
important for hand therapists to assess impairment and tracking
progress among patients. Moreover, past research has suggested
that Saudi children have lower values of height and weight
than Western children.28,29 This variation in demographic
characteristics might influence grip strength and dexterity vs
existing Western demographics. Therefore, the norms of grip
strength and manual dexterity from Western countries are
inappropriate because they did not consider the differences in
physical characteristics according to race/ethnicity and region.20
Therefore, the purpose of this study was to develop reference
values for grip strength and dexterity function in Saudi children
aged 6-12 years.
Methods
Subjects
Elementary school children (6-12 years; n ¼ 525) were recruited
from the urban central area of Riyadh, Saudi Arabia. All children and
their parents signed consent form describing the aims and
procedures of this study. The study was approved by the Ethics
Committee, Rehabilitation Research Chair, King Saud University,
Saudi Arabia. To establish accurate norms, children with certain
abnormalities were excluded from this study such as cognitive/
neurologic disorders, delayed milestones, pain or functional
limitations of the upper limbs, or inability to understand the test
procedures.
Instrumentation and procedures
Researchers collected the demographic data, including age,
gender, weight, and height. The body weight was measured using a
portable weighing scale (Camry, model: EF921; Zhonghan, Camry
Electronic, Co, Ltd, China) to the nearest 0.1 kg. The height was
measured with a stadiometer to the nearest 0.1 cm. Then, body
mass index was computed. Hand dominance was determined by
the child’s reported preference for use in activities of daily living,
such as writing, eating, throwing a ball, and opening and closing
doors or window shutters.8,20 All measurements were obtained in
the air-conditioned room of the health supervisor during the school
day from 8 to 11 AM. The children were allowed to short practice
using the dynamometer and 9-HPT to become familiar with test
procedures. A sample of 40 children was randomly selected to
evaluate test-retest reliability of the hand dynamometer and 9-HPT
among Saudi children under the same conditions and procedures
with a mean interval of 7 days.
Assessment of hand grip strength
Hand grip strength was measured using a standard adjustable
hand dynamometer (J-Tech 12-0259 Commander Grip Track
Dynamometer, JTECH Medical, Midvale, UT, USA) based on the
recommendation of the American Society of Hand Therapists.5
For standardization, the dynamometer was set at the second
handle position for measurement of hand grip strength. Grip
strength was measured while children were in a sitting position
with shoulder adducted and neutrally rotated, elbow at 90 flexion,
and the forearm and wrist in neutral position.4,30,31 Children were
instructed to squeeze the handle of the dynamometer as hard as
they could and to sustain the effort for 5 seconds. Verbal encouragement (ie, squeeze as hard as you can) was provided to children
during testing. Children performed 3 trials for each hand, and the
mean values of these trials were recorded. Children were given 1
minute to rest between trials, and trials were completed with
alternating hands to minimize the effects of fatigue.32 Results were
recorded in pounds. If a measurement showed a difference greater
than 10% from previously obtained measurements, then we did not
retain that measurement and instead conducted a fourth trial.21
These procedures have been previously well documented as reliable.33,34 The calibration of instruments was tested periodically
during the study according to the manufacturer’s manual.
Assessment of hand dexterity
Hand dexterity was measured using the 9-HPT (Sammons
Preston, PO Box 93040, Chicago, IL). The 9-hole pegboard is on a 5inch square pegboard. Each peg hole is 3 cm deep, 2.5 cm diameter,
and located 2 cm from adjacent peg holes, which are arranged in 3
rows of 3. Each peg measures 4 cm in height and 2.2 cm in diameter
and has a dot marked on 1 side. A stopwatch was used to time the
9-HPT. The procedures described by Mathiowetz et al35 were used
in this study. Each child was tested separately while he and she sat
at a desk and chair of appropriate height with their feet supported
on the floor to ensure that the tabletop was at the midchest level.
The pegboard was centered in front of a child with the container
next to the board on the same side of the hand being tested.7-9 The
dominant hand was tested first followed by the nondominant hand.
The child was instructed to pick up 1 peg at a time using 1 hand
only and to put them in the holes until all 9 were filled. The child
then removed the pegs from the holes one by one. The order of
placement was not prescribed. For the nondominant hand, the
pegboard was turned so that the container was on the same side as
the nondominant hand. During the test, the therapist instructed the
child not to touch the peg with the free hand and chest.7-9 The score
was the total time in seconds to complete the task. Timing began on
contact with the first peg and ended with return of the final peg to
the dish. The average time of 3 trials was used in analysis.
Statistical analysis
Data were described as mean and standard deviation for
continuous variables and median and mode for categorical variables. Test-retest reliability was analyzed using interclass correlation coefficient (ICC). Unpaired and paired t tests were used to
determine between-subjects and within-subject differences
regarding hand grip differences and dexterity, respectively. A 2-way
mixed-design analysis of variance was used to compare sex (between-subject factor) and hand dominance (within-subject factor).
The Tukey post hoc test in separate analyses of variances was used
to examine differences between specific age groups for boys and
girls. Correlation between variables was assessed using Pearson
correlation coefficient, and simple and multiple liner regression
M.T.A. Omar et al. / Journal of Hand Therapy xxx (2017) 1e8
3
Table 1
Physical characteristics of the children who participated in the study
Age
Boys
N
Girls
Right dominance
Left dominance
Weight (kg)
Height (cm)
N
Right dominance
Left dominance
Mean (SD)
6
7
8
9
10
11
12
Total
29
34
30
20
37
41
31
222
27
32
23
17
34
37
26
196
2
2
7
3
3
4
5
26
21.04 (3.01)
23.46 (2.06)
27.06 (2.77)
28.25 (2.35)
33.21 (3.47)
36.87 (4.38)
41.77 (5.99)
30.72 (7.84)
Weight (kg)
Height (cm)
Mean (SD)
116.72 (2.80)
119.82 (2.92)
125.23 (2.86)
132.40 (2.39)
135.67 (4.70)
139.29 (4.96)
146.48 (2.93)
131.24 (10.6)
22
49
56
51
33
56
36
303
20
46
49
48
31
53
32
279
2
3
7
3
2
3
4
24
22.13 (2.88)
23.51 (2.65)
27.19 (4.71)
29.82 (5.76)
34.18 (5.87)
38.19 (6.58)
42.44 (4.65)
31.28 (8.32)
115.04 (3.04)
119.12 (3.94)
123.80 (5.05)
130.96 (4.21)
134.06 (4.70)
137.07 (7.24)
144.89 (5.42)
129.68 (10.31)
N ¼ number of participants; SD ¼ standard deviation.
analyses were used to determine relations and variability between
variables. In addition, the percentile curves were constructed for
the hand grip and dexterity for boys and girls separately. The percentiles for hand grip and dexterity for boys and girls were separately estimated. Percentile curves were plotted against the age
with 5 points placed at the 10th, 25th, 50th, 75th, and 90th centiles.
All statistical analyses were performed with the Statistical Package
for Social Sciences (SPSS, version 21.0; SPSS Inc, Chicago, IL). Statistical significance was set at P < .05.
Results
Physical characteristics of the subjects
Table 1 describes the physical characteristics of the participating children. Five hundred twenty-five children completed the
test procedures: 222 (42%) were boys and 303 (58%) were girls.
Right-hand dominance was reported in 475 children (90.5%)
comprising 196 (37.3%) boys and 279 (53.2%) girls, whereas 50
children (9.5%) reported left-hand dominance comprising 26
(4.9%) boys and 24 (4.6%) girls. None of the children reported
ambidexterity. There were no differences in the weight (P > .05)
and height (P > .05) between boys and girls in each age group.
There was a significant and steady increase in weight (P < .05) and
height (P < .05) with age. However, there were no significant
differences in weight for 6-7 year olds (boys, P > .36; girls, P > .98)
and 8-9 year olds (boys, P > .97; girls, P > .31) and height at 6-7
year olds (boys, P > .08; girls, P > .15) and 9-10 year olds (boys, P >
.11; girls, P > .32).
The results of test-retest reliability from study sample (n ¼ 40)
were analyzed. Children showed high to very high test-retest reliability for Jamar dynamometer (0.81 ICC 0.95; P .001) and 9HPT (0.80 ICC 0.91; P .001).
Hand grip strength
Table 2 represents reference value of hand grip strength according to age, hand dominance, and gender. There were significant
main effects for age (F ¼ 269.47; P < .01) and gender (F ¼ 133.09; P
< .01) and a significant age by sex interaction (F ¼ 84.45; P < .01).
The grip strength was increased with age regardless of gender and
toward the older children for both dominant (boys: F ¼ 122.5, P <
.001; girls: F ¼ 132.98, P < .001) and nondominant hands (boys: F ¼
112.4, P < .001; girls: F ¼ 100.29, P < .001). However, 6-7-year-old
and 9-10-year-old children did not show significant differences in
grip strength in either boys (P > .05) or girls (P > .05). Comparison
of hand grip strength for the dominant vs nondominant hands
indicated nonsignificant differences regardless of gender (P > .05).
However, the grip strength of the dominant hands tends to be
higher than that of the nondominant hands in all age groups, except
for 7-year-old children in both genders.
Across all age groups, the hand grip strength of boys was significantly higher than that of girls for dominant hand (31.75 10.33 vs
28.24 9.35; P < .001) and nondominant hand (31.01 10.27 vs
Table 2
Mean values of hand grip strength (pounds) using Jamar dynamometer across age range and gender
Grip strength for boys
Grip strength for girls
Hand
Age (y)
N
Mean SD
Minimum
Maximum
Hand
Age (y)
N
Mean SD
Minimum
Maximum
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
6
29
49
30
8
56
9
20
9
51
10
37
10
33
11
41
11
56
12
31
12
36
Total
222
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
7
8
22.94
22.61
30.33
29.00
39.67
35.00
46.33
41.67
49.33
43.00
49.67
47.33
57.30
55.34
57.30
55.34
22
34
15.27
14.94
15.33
13.67
20.00
18.00
24.00
23.67
24.00
22.67
29.33
25.00
38.44
35.10
15.27
13.67
6
7
19.15 2.23
18.34 2.34
21.82 4.94a
21.29 4.14a
26.52 4.79a,b
25.86 4.51a,b
32.28 5.44a,b
31.08 6.02a,b
33.89 6.12a
32.81 5.05a
39.09 4.76a,b
38.49 5.34a,b
46.86 5.59a,b
46.41 5.28a,b
31.75 10.33a
31.01 10.27a
Total
303
17.88 3.20
17.33 3.43
18.92 4.19
18.04 3.85
23.30 5.84b
22.68 5.58b
27.63 5.82b
26.97 6.28b
29.76 6.48
28.26 7.70
36.25 3.95b
34.40 4.14b
41.92 5.81b
41.36 5.67b
28.24 9.35
27.27 9.30
10.56
9.96
12.68
12.98
13.80
13.80
19.00
19.00
20.60
20.60
27.60
26.10
32.20
32.20
10.56
9.96
22.76
21.66
30.58
29.18
37.00
35.80
41.20
39.80
47.00
40.40
47.60
44.60
53.70
51.40
53.70
51.40
N ¼ number of participants; SD ¼ standard deviation.
a
Significantly different between boys and girls within age group (P < .005).
b
Significantly different from previous age group (P < .05).
4
M.T.A. Omar et al. / Journal of Hand Therapy xxx (2017) 1e8
Table 3
Summary of sample and multiple liner regression of hand grip strength for boys and
girls separately and for both genders combined
Gender
Hand dominance
Boys
Dominant
Dominant
Nondominant
Nondominant
Girls
Dominant
Dominant
Nondominant
Nondominant
All combined (both hands and
both sex)
All combined (both hands and
both sex)
Model variables
R2
Age
Age, weight, and height
Age
Age, weight, and height
Age
Age, weight, and height
Age
Age, weight, and height
Age
0.79
0.80
0.77
0.78
0.69
0.71
0.70
0.72
0.72
Age, weight, and height
0.75
27.27 9.30; P < .001). Boys were significantly stronger than girls
with the dominant hand at ages 7 (P ¼ .02), 8 (P ¼ .04), 9 (P ¼ .003), 10
(P ¼ .001), 11 (P ¼ .001), and 12 (P < .001). For the nondominant hand,
this was true at ages 7 (P ¼ .03), 8 (P ¼ .02), 9 (P < .001), 10 (P < .001),
11 (P ¼ .01), and 12 (P < .001). There was no difference in grip
strength between boys and girls at 6 year olds for both dominant
(P ¼ .10) and nondominant (P ¼ .20). The percentage difference in
grip strength between boys and girls was fluctuated from 6.5% to 15%
for 6-year-old and 12-year-old boys, respectively.
To establish the association of gender, age, height, and weight
with grip strength in more detail, we performed a multilevel
analysis with the simpler and multiple level model analysis as
shown in Table 3. For both the dominant and nondominant hands,
the age, height, weight, and gender had a significant association
with grip strength (P .001). In the boys, the R2 for the dominant
and nondominant hands was 0.80 (P < .001) and 0.78 (P < .001)
indicating that the combination of age, weight, and height
accounted for 80% and 78% of the variability in hand grip strength.
In the girls, the R2 for the dominant and nondominant hands was
0.71 (P < .001) and 0.72 (P < .001) indicating that the combination
of age, weight, and height accounted for 71% and 78.2% of the
variability in hand grip strength. This analysis showed that for both
genders, the parameters age, weight, and height accounted for
most of the variability in grip strength. The contribution of age,
weight, and height was significant for both girls and boys (P < .01 in
all cases).
Figure 1A-D presented the centile curves for the hand grip for
boys and girls aged 6-12 years. Scores are plotted as 10%, 25%, 50%,
75%, and 90% percentiles. The upper and lower limits indicate the
borders of reference values for strength at the corresponding age.
Manual hand dexterity
Table 4 represents reference values for 9-HPT according to age,
hand dominance, and gender. The speed of dexterity improved
with age regardless of gender and toward the older children for
both dominant hands (boys: F ¼ 71.68, P < .001; girls: F ¼ 58.24, P <
.001) and nondominant hands (boys: F ¼ 96.57, P < .001; girls: F ¼
95.30, P < .001). However, the scores for dominant hand between
6-7-year-old, 9-10-year-old, and 11-12-year-old children were
similar in boys (P > .05) and girls (P > .05). The results are similar for
the nondominant hand. Regardless of gender, the dominant hand
demonstrated shortest completion time than nondominant hand (P
< .001) at every age group.
Across all age groups, the girls performed slightly faster than
boys for dominant hand (19.70 vs 20.68; P < .05) and nondominant
hand (21.79 vs 23.46; P < .05). In general, girls completed a 9-HPT
faster than boys in 2 of 7 age groups: 11 years (9-HPT scores ¼ 2.10
seconds; P < .01) and 12 years (9-HPT scores ¼ 1.93 seconds; P <
.01).
Figure 2A-D represents reference values for 9-HPT in seconds
according to age, hand dominance, and gender. Scores are plotted
as 10%, 25%, 50%, 75%, and 90% percentiles. The upper and lower
limits indicate the borders of reference values for 9-HPT at the
corresponding age.
Discussion
To our knowledge, this is the first published normative data of
hand grip strength and manual dexterity function in 6-12-year-old
Saudi children. In the present study, a hand dynamometer and 9HPT were used to measure grip strength and hand dexterity and
demonstrated a high to very high test-retest reliability. This confirms the literature stating good-to-excellent test-retest (r > 0.80)
reproducibility for Jamar dynamometer34,36 and 9-HPT (r ¼ 0.81),7
which supports their use as objective measures to determine hand
grip strength and manual dexterity among Saudi children. Moreover, besides having a high test-retest reliability, all children were
Table 4
Mean values of time to complete the 9-HPT (seconds) for manual dexterity across age range and gender
9-HPT for boys
9-HPT for girls
Hand
Age (y)
N
Mean SD
Minimum
Maximum
Hand
Age (y)
N
Mean SD
Minimum
Maximum
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
6
29
49
30
8
56
9
20
9
51
10
37
10
33
11
41
11
56
12
31
12
36
Total
222
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
Dominant
Nondominant
7
8
32.30
32.70
30.43
31.23
28.93
30.90
23.73
25.53
23.68
25.43
20.82
22.75
19.84
22.44
32.30
32.70
22
34
21.09
25.01
19.63
20.13
18.97
20.67
17.27
18.83
15.99
16.69
14.28
16.69
12.05
15.02
12.05
15.02
6
7
25.18 2.83
29.20 2.28
24.62 2.81
27.60 2.69
22.18 2.29a
24.63 2.60a
19.88 1.76a
22.37 1.79a
19.46 2.21
21.90 2.12
17.49 1.48a
19.96 1.54a
16.87 1.63
19.63 1.66
20.68 3.79
23.46 4.05
Total
303
24.71 2.59
28.33 3.28
23.61 2.88
26.80 2.97
21.31 3.34a
23.86 3.26a
19.46 2.42a
21.02 2.40a
18.50 2.99
21.00 2.82
16.07 2.64a,b
17.19 2.63a,b
15.88 2.48b
16.75 2.39b
19.70 4.10b
21.79 4.78b
20.70
23.92
16.10
20.10
14.50
18.50
14.50
13.20
12.50
16.40
10.10
11.80
12.80
12.50
10.10
12.50
31.30
35.60
31.10
34.50
28.50
32.80
23.90
24.20
24.80
24.70
21.50
24.50
21.50
21.50
31.30
37.30
N ¼ number of participants; SD ¼ standard deviation.
a
Significantly different from previous age group (P < .05).
b
Significantly different between boys and girls within age group (P < .005).
M.T.A. Omar et al. / Journal of Hand Therapy xxx (2017) 1e8
5
Fig. 1. Reference values for grip strength according to gender, dominance, and age. Scores are plotted as 10, 50, 75, and 90 percentiles. The upper and lower limits indicate the
borders of reference values for strength at the corresponding age.
measured in the same manner and again to follow standardized
methods according to the American Society of Hand Therapists
protocol.5
Normative data for grip strength are usually presented in table
format or as growth curves as a function of age.21,37 The latter
approach was chosen in the present study to illustrate grip strength
development at different ages. Our data confirm significant difference
and progressive increases in hand grip strength with age in favor of
the older children across both genders, and the differences in grip
strength between boys and girls are varied across age. The described
curve of grip strength showed a trend for boys to be stronger than girls
in almost age groups (except for 6 year olds) and marked acceleration
of grip strength around 10-12 years, specifically for boys.
The overall patterns of hand grip strength observed in the present study are similar to the previous studies that established acceleration of grip strength with advanced age.8,12,20-22,36,37
Considering gender and age, the grip strengths in boys and girls
at 6 years were similar, when dominant or nondominant hands
were tested. This aligns with the results of Robertson and Deitz,18
De-Smet and Vereammen,19 and Häger-Ross and Rösblad20 who
found no differences in grip strength for those younger than 7
years. Differences between genders in grip strength were apparent
by 10 years in the present study. This results in agreement with
Häger-Ross and Rösblad20 and Moura et al38 who concluded that
boys are stronger than girls particularly after 10 years. Moreover,
fluctuated differences in the percentage of grip strength observed
in the present study are in accordance with the results of Molenaar
et al,21 who concluded that, the difference in grip strength between
boys and girls does not appear to be the same for each age, and boys
are always stronger.
The gender differences and acceleration of hand grips around
10-12 years are partially attributed to the onset of puberty and
biological maturity (eg, muscles mass, total body mass, and height),
which has a strong impact on strength measures especially for
boys.20,39,40 Moreover, data from a limited number of studies
indicate that 60% of Saudi children and 71% of young people do not
engage in physical activity of sufficient duration and frequency,40-43
and families may not encourage girls to take part in leisure time and
activities either inside or outside school.41-43 These lifestyle
changes and physical inactivity are believed to influence muscular
6
M.T.A. Omar et al. / Journal of Hand Therapy xxx (2017) 1e8
Fig. 2. Reference values for 9-HPT (seconds) according to gender, dominance, and age. Scores are plotted as 10, 50, 75, and 90 percentiles. The upper and lower limits indicate the
borders of reference values for 9-HPT strength at the corresponding age. 9-HPT ¼ 9-hole pegboard test.
strength among Saudi children and might be responsible for
gender-specific differences in hand grip strength.
In the present study, nonsignificant differences in grip strength
were reported between dominant and nondominant hands for all
ages regardless of genders. However, the scores of the dominant
hands tend to be higher than that of the nondominant hands in all
age groups. These results are similar to the previously published
reports,8,13,16,19,22 which demonstrated nonsignificant differences
between dominant and nondominant hands. In contrast, some
studies reported significant differences according to the hand
dominance.21,37,44 Furthermore, grip strength was positively
correlated with height and weight, and it was consistent with the
previous studies.21,22,37 Therefore, the reason for this contradictory
needs to be clarified in the future, and the therapist should
consider age, sex, weight, and height when comparing their
children’s measurement with normative values and in clinical
practice.
Comparing grip strength results with former studies in more
detail proved to be difficult due to differences in methods between
studies. Both Ager et al13 and McQuiddy et al22 reported scores
according to the right or left hand and not according to dominance,
whereas Newman et al14 contained use of a different device that is
no longer commonly used, and age subgroups were not divided in
the same way, and the variable dominance was not considered,
using right and left hands instead. Where comparison was possible,
the results of the present study were relatively lower than those of
Ploegmakers et al37; however, the 2 attempts for each hand were
performed, but the age subgroups were similar to the present
study. Moreover, our results were lower than those of Molenaar
et al21 and Ferreira et al,44 where 3 attempts were allowed; however, the age subgroups were not divided in the same way in the
later study. In addition, the results of present study were relatively
lower than early finding of De-Smet and Vereammen19 who
allowed only 1 attempt with each hand.
Our data confirm significant and faster performance scores on
the 9-HPT in older children than younger children in both genders.
These findings were supported by previously published research
from other countries.7-9,45 In this study, the children’ scores of hand
dexterity using 9-HPT were slightly slower than that of Smith et al7
and Poole et al9 and approximately similar to the scores reported in
M.T.A. Omar et al. / Journal of Hand Therapy xxx (2017) 1e8
the study by Yim et al8 but slightly faster than scores reported for
the study of Wang et al.45 In addition, the youngest subjects, aged 6
years, had performance scores of 26.36 seconds, whereas 12-yearold children had the lowest mean performance scores of 18.87
seconds. This showed that fine motor dexterity was faster in older
children than younger ones. This variation in scores of fine manual
dexterities is supported by the work of Folio and Fewell46 and
Pehoski et al47 and might be attributed to maturation of the brain
and corticospinal tract. The white matter increases and the gray
matter decreases in childhood and adolescence. Thus, the associated increases in myelination and axon diameter are favorable for
increased motor speed of motor performance.48 In addition, Slowne
says “It seems that girls are really better at motor skills than boys at
the age of 6 to 13 years.”49 Moreover, grade-school girls tend to
excel in speed and accuracy of handwriting compared with boys.
This probably reflects their faster maturation.41-55 However, none
of this association has been studied in Saudi children. Regardless of
the group, our findings show that the girls typically perform faster
than boys. In addition, the dominant hands were more dexterous
than nondominant hands. These findings are consistent with results of Smith et al,7 Poole et al,9 Wang et al, and others.45
Discrepancy in hand grip strength and dexterity function of
Saudi children in the present study might be related to certain
aspects of their lifestyle and environmental factors (eg, availability
of high-fat and dense-caloric foods, satellite TV, increased reliance
on computer, and telecommunication technology as well as
decreased leisure and recreation time) over the past few decades
and sedentary lifestyles among Saudi children,41-43 as well as racial
and anthropometric differences between them and Western populations.7-9,12-20,26 Recently, Jeune et al27 compared the hand grip
strength across regions and found that it may provide some insight
as to the historical regional differences in genetic factors, nutritional deficiencies, and sociocultural environment. Our data suggest that grip strength norms and dexterity function from the
Western population may not accurately represent the local population; hence, local reference values are needed. Moreover, making
direct comparison between hand function reported here and previous research is difficult because of variations in the protocol used
for measurements and the methods of reporting the scores. These
variations include differences in the number of trials and types of
the dynamometer and pegboard, whether dominant or nondominant or both hands are assessed, and if the mean of 2 or more trials
or the highest value is reported.
Some limitations of this study are data collection occurred in a
localized region from the urban central area of Riyadh, King Saudi
Arabia limiting generalizability of the study results and only to the
age range of 6-12 years. The cohort was not representative of a broad
range of the sociocultural and economic aspects of Saudi Arabia.
Thus, further study using the same standardized procedures in
another area within the country is required. In addition, the growth
diagrams do not represent the development of the grip strength and
dexterity function in children with hand disorders. However, the
curves allow discriminations of the development of typical children
and evaluate the effects of therapeutic interventions.
Conclusion
Normative values of hand grip strength and dexterity identify
some developmental characteristics of hand function among
Saudi children aged 6-12 years old. These growth curves of grip
strength and dexterity function norms will allow rehabilitation
therapists to determine the presence of impairment, monitor
progression overtime, and compare scores from children in
different clinical settings. In addition, the results from this study
show that gender, age, height, and weight are positively
7
associated with the development of grip strength and dexterity
function in children.
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