Association between Handgrip Strength and Raw BIA Variables in
Adolescents Aged 14-17 Years
Paola Alicante
1
, Ada Di Gregorio
1
, Anna Maria Sacco
1
, Fabiana Monfrecola
1
,
Luca Scalfi
1
and Giuliana Valerio
2
1
Department of Public Health, Federico II University of Naples, Via S. Pansini 5, Naples, Italy
2
Department of Movement Sciences and Wellbeing, University of Naples “Parthenope”, Via Medina 40, Naples, Italy
Keywords: Handgrip Strength, Body Composition, BIA, Phase Angle, Impedance Ratio, Bioimpedance Index.
Abstract: Raw BIA (bioelectrical impedance analysis) variables such as phase angle (PhA) or impedance ratio (IR=the
ratio between impedance-Z at high frequencies and Z at low frequencies), are both thought to be a proxy of
muscle quality in terms of water distribution (ECW/ICW ratio), body cell mass and cellular integrity. So far,
few studies have tested the relationship between handgrip strength (HGS) and body composition in adoles-
cents. Our study aimed to analyze the variability in raw BIA variables and their association with HGS in 117
male (age 15.7±0.8 years, stature 171.8±7.3 cm, body weight 65.8±10.6 kg, standardized body mass in-
dex=BMI-SDS +0.57±0.9) and 130 female adolescents (age 16.0±0.7 years, stature 160.8±5.6 cm, weight
57.3±8.0 kg, BMI-SDS +0.38±0.9). BIA was performed for the whole body and separately for upper limbs
and lower limbs, while HGS was measured to assess the isometric strength of upper limbs. HGS was signifi-
cantly correlated (r>0.500) with whole-body IR and PhA, and this association was even stronger with upper-
limb IR and PhA. In addition, a quite strict correlation emerged between HGS and whole-body BI index at
250 kHz (index of fat-free mass). In multiple regression analysis BI indexes along with IRs or PhAs were
independent predictors of HGS, whereas gender and age were not. In conclusion, this study gives some infor-
mation about the use of HGS and raw BIA variables in the first two decades of life, suggesting a new approach
to assess nutritional status in prevention and public health nutrition.
1 INTRODUCTION
The assessment of handgrip strength=HGS (maximal
isometric grip force task) is a commonly applied
method for evaluating muscle strength in general
population and in patients suffering from various
diseases, which may be applied both in public health
nutrition and clinical nutrition (Beaudart et al., 2019).
Changes in muscle strength occur from childhood
to adolescence due to muscle mass and function
development; for instance, variations of HGS in
children can be ascribed to an increase in both muscle
mass and muscle section strength (Neu et al., 2002).
Interestingly, a recent study conducted on
approximately two million children and adolescents
has found an increasing trend of absolute gripping
force from 1967 to 2017 (Dooley et al., 2020).
The literature has indicated that HGS is a
predictor of bone strength in children (Hyde et al.,
2020) and that in the first two decades of life
measuring HGS allows to identify early abnormalities
and prevent low muscle mass in adulthood (Orsso et
al., 2019). In addition, low muscle mass and strength
have been associated in children and adolescents with
both an increased risk of cardiometabolic diseases
(Kim et al., 2015; Peterson et al., 2016) and metabolic
syndrome (Kang et al., 2020), and alterations in bone
parameters (Dorsey et al., 2010) and neuro-
development (Kar et al., 2008; Ramel et al., 2016).
In children and adolescents HGS is influenced by
several factors including preferred limb, age, gender,
stature, body weight, and body composition (De
Souza et al., 2014; Silverman, 2015; Montalcini et al.,
2016). In human nutrition and prevention, body
compartments are commonly assessed using
bioelectrical impedance analysis (BIA) with respect
to fat-free mass (FFM), body fat (FM), body cell mass
(BCM), total body water (TBW), extracellular water
(ECW) and intracellular water (ICW) (Kyle et al.,
2004). Research is now focused on directly-measured
raw BIA variables such as phase angle (PhA) or
impedance ratio (IR=the ratio between impedance-Z
Alicante, P., Di Gregorio, A., Sacco, A., Monfrecola, F., Scalfi, L. and Valerio, G.
Association between Handgrip Strength and Raw BIA Variables in Adolescents Aged 14-17 Years.
DOI: 10.5220/0010066501390143
In Proceedings of the 8th International Conference on Sport Sciences Research and Technology Support (icSPORTS 2020), pages 139-143
ISBN: 978-989-758-481-7
Copyright
c
2020 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
139
at high frequencies and Z at low frequencies), which
are thought to be indexes of water distribution
(ECW/ICW ratio), BCM and cellular integrity
(Earthman et al., 2007; Gonzalez et al., 2016; de
Blasio et al., 2017). IR and PhA have also been shown
to be directly related to muscle strength and physical
activity (de Blasio et al., 2017; Mundstock et al.,
2019). More specifically, PhA was associated to HGS
(Martins et al., 2020) and to cardiorespiratory fitness
in the first two decades of life (Langer et al., 2020),
and it was used in assessing body composition in
young and adolescent athletes (de Araújo Jerônimo et
al., 2020). To extend these findings, we aimed to
evaluate in healthy adolescents the relationships of
HGS with raw BIA variables (PhA and IR), which
were measured for the whole body and in addition on
upper limbs and lower limbs, separately.
2 METHODS
This cross-sectional study included two hundred and
forty-seven adolescents participated in the study: 117
males (age 15.7±0.8 years, stature 171.8±7.3 cm,
body weight 65.8±10.6 kg, standardized body mass
index=BMI-SDS +0.57±0.90) and 130 females
(16.0±0.7 years, 160.8±5.6 cm, 57.3±8.0 kg, BMI-
SDS +0.38±0.90).
All parents/guardians signed the informed consent
form authorizing participation in the survey and
adolescents signed the assent. The target population
was adolescents of both sexes aged 1417 years
enrolled in two different high schools in Naples. All
participants were healthy and free of any lesion or
impairment in the upper limbs. The participants
avoided exercising 12 hours before testing; they were
studied in the morning after an overnight fasting, by
the same operator and following standard procedures.
Body weight was measured to the nearest 0.1 kg
using a platform beam scale and stature to the nearest
0.5 cm using a stadiometer (Seca 216; Seca, Ham-
burg, Germany). BMI-SDS was then calculated in ac-
cording to the World Health Organization=WHO
growth reference for school-aged children and ado-
lescents (de Onis et al., 2007).
Concerning BIA, Z and PhA were measured at
frequencies between 5 and 250 kHz (HUMAN IM
TOUCH analyzer, DS MEDICA, Milano). BIA data
for the whole body and separately for upper limbs and
lower limbs (segmental BIA) were considered as fol-
lows: 1) bioimpedance indexes at 5 and 250 kHz (BI
index=stature²/Z), as markers of ECW and FFM, re-
spectively; 2) IR= the ratio between Z at 250 kHz and
Z at 5 kHz; 3) PhA at 50 kHz. BIA variables were
considered for statistical analysis as the mean of
measures on right and left body sides. FFM and FM
were calculated using the equations proposed by Sun
et al. (2003).
Handgrip strength (HGS) was determined using a
Dynex dynamometer (MD systems Inc. Ohio USA)
to assess isometric strength of upper limbs. The max-
imum value (whole body) considering three attempts
on the preferred limb and three attempts on the non-
preferred limb of the body was used for analysis. The
adolescents were standing during the entire test with
the arm straight down at the side and performed 3
maximal isometric contractions (each lasting 5 sec-
onds) with each hand, with a 1 minute rest between
preferred limb tests (Gerodimos et al., 2017).
2.1 Statistical Analysis
Results are expressed as mean±standard deviation.
Statistical significance was pre-determined as
p<0.05. All statistical analyses (independent t-test,
partial correlation, multiple regression) were per-
formed using the Statistical Package for Social Sci-
ences (SPSS) version 24. The Kolmogorov-Smirnov
test was employed to determine the normality of data
distribution.
3 RESULTS
The general characteristics of the study groups are
summarized in Table 1. Male adolescents were taller
and heavier than the female ones. FFM (from BIA)
was significantly higher in males, even after adjust-
ment for body weight (p<0.001).
Table 1: Individual characteristics and body composition in
117 male and 130 female adolescents.
Male
adolescents
Female
adolescents
Age (age)
15.7
±0.8
16.0
±0.7
a
Weight (kg)
65.8
±10.6
57.3
±8.0
a
Stature (cm)
171.8
±7.3
160.8
±5.6
a
BMI-SDS
+0.57
±0.90
+0.38
±0.86
FFM (kg)
54.2
±7.4
42.1
±4.1
a
FM (kg)
11.5
±5.9
15.2
±6.0
a
FM (%)
16.8
±7.1
25.8
±7.6
a
mean±standard deviation;
BMI-SDS=standardised body mass index, FFM=fat-free
mass, FM=fat mass;
a=p<0.05 between genders
icSPORTS 2020 - 8th International Conference on Sport Sciences Research and Technology Support
140
With respect to raw BIA variables (Table 2), BI
indexes were higher in male compared to female ad-
olescents at both 5 and 250 kHz (whole body +31.9%
and +34.1%, upper limbs +35.4% and +38.2%, lower
limbs +29.0% and +31.1%, respectively); this was
true even after controlling for body weight (p<0.001).
There were also significant variations between
genders in IRs, which were lower in males, and PhAs
(in males, +4.9% for the whole body, +12.9% for up-
per and +3.5% for lower limbs) (Table 3).
Table 2: Bioimpedance indexes (BI indexes) calculated for
the whole body in 117 male and 130 female adolescents.
BI index (cm
2
/kHz)
Male
adolescents
Female
adolescents
49.6
±8.0
37.6
±5.4
a
57.4
±10.2
42.9
±6.7
a
66.9
±12.2
49.9
±7.9
a
mean±standard deviation;
a=p<0.05 between genders
We assessed muscle strength by measuring HGS
(Table 4). A statistical difference emerged between
genders for the whole body, preferred limb and non-
preferred limb (in all cases around +28% in males).
After adjustment for body weight the differences
were reduced but still present (adjusted means: whole
body 35.5 vs 29.2 kg, preferred limb 35.1 vs 28.8 kg,
non-preferred limb 32.9 vs 27.4 kg).
The association of HGS with stature, weight, and
BMI-SDS was first evaluated by partial correlation,
after adjusting for group. HGS (whole body, preferred
limb and non-preferred limb) was weakly (r<0.300)
associated with stature, body weight and BMI-SDS.
Table 3: Impedance ratio (IR= Z 250 kHz/Z 5 kHz) and
phase angle (PhA) at 50 kHz measured on the whole body
and limbs in 117 male and 130 female adolescents.
Male
adolescents
Female
adolescents
IR
Whole body
0.745
±0.027
0.755
±0.022
a
Upper limbs
0.756
±0.028
0.770
±0.021
a
Lower limbs
0.741
±0.032
0.752
±0.030
a
Phase angle (degrees)
Whole body
6.82
±0.85
6.50
±0.80
a
Upper limbs
5.16
±0.90
4.57
±0.72
a
Lower limbs
9.21
±1.22
8.90
±1.19
a
mean±standard deviation;
a=p<0.05 between genders
Strong correlations (r>0.500) emerged with whole-
body IR and PhA, and even stronger with upper-limb
IR and PhA (Table 5). Interestingly, a weaker corre-
lation emerged for BI index at 5 kHz while a higher
correlation was observed between HGS and whole-
body BI index at 250 kHz (data not show).
Table 4: Handgrip strength in 117 male and 130 female ad-
olescents for the whole body, preferred limb and non- pre-
ferred limb.
Handgrip strength (kg)
Male
adolescents
Female
adolescents
Whole body
36.4
±10.5
28.4
±7.4
a
Preferred limb
35.9
±10.4
28.0
±7.3
a
Non-preferred limb
34.0
±10.3
26.5
±7.4
a
mean±standard deviation;
a=p<0.05 between genders
Multiple regression analysis (on the whole body)
showed that BI indexes along with IR or PhA were
independent predictors of HGS, whereas gender and
age were not.
Table 5: Partial correlation of handgrip strength (HGS) with
impedance ratio (IR=Z 250 kHz/Z 5 kHz) and phase angle
(PhA) for the whole body and upper limbs.
Handgrip strength (kg)
IR
whole
body
IR
upper
limb
PhA
whole
body
PhA
upper
limb
Whole body
˗0.625
*
˗0.672
*
0.645
*
0.712
*
Preferred limb
˗0.620
*
˗0.669
*
0.640
*
0.706
*
Non-preferred limb
˗0.610
*
˗0.644
*
0.638
*
0.695
*
*=p<0.05
4 DISCUSSION
This study shows that HGS was significantly related
to whole-body raw BIA variables in both male and
female adolescents, and even more strictly to upper-
limb IR and PhA.
As first point, FFM and FM (from BIA) signifi-
cantly differed between genders with a consistent
higher FFM in males and a higher FM in females, in
agreement with that is commonly known on body
composition in the second decade of life (Wang et al.,
2014; Schmidt et al., 2018).
Then, we looked at those raw BIA variables such
as IR or PhA that are likely to be related with water
distribution (ECW/ICW ratio), BCM and cellular in-
tegrity (Earthman et al., 2007; Gonzalez et al., 2016;
de Blasio et al., 2017). They have also been shown to
Association between Handgrip Strength and Raw BIA Variables in Adolescents Aged 14-17 Years
141
be significantly associated with HGS (Martins et al.,
2020) and cardiorespiratory fitness in children and
adolescents (Langer et al., 2020).
Results are available not only on whole-body PhA
but also, for the first time, on IR and segmental BIA.
Difference between genders emerged for IRs and
PhAs, which were more marked with regard to upper
limbs (for instance, PhA in males, +4.9% for the
whole body, +12.9% for upper limbs and +3.5% for
lower limbs). This finding was in line with the previ-
ous study by Schmidt et al., (2018) on whole-body
PhA.
HGS, is a reliable index of musculoskeletal fitness
varies in children and adolescents (Castro-Pinero et
al., 2010), depending on factors such as age, gender,
stature, weight, preferred limb and body composition
(De Souza et al., 2014; Silverman, 2015; Montalcini
et al., 2016). We used a Dynex dynamometer to de-
termine isometric strength of upper limbs in male and
female adolescents from fourteen to seventeen years
old. A statistical difference occurred between male
and female adolescents for the whole body, preferred
limb and non-preferred limb, as previously described
by Omar et al. (2015).
To the best of our knowledge, a single study has
so far yielded evidence on the direct association be-
tween HGS and whole-body PhA (Martins et al.,
2020). Our results showed that all raw BIA variables
were direct predictors of HGS. This was the case of
BI index at high frequency (250 kHz), which is
known to be strictly related to TBW and FFM (Kyle
et al., 2015). Interestingly, a weaker correlation
emerged for the BI index at 5 kHz, which is likely to
be an index of ECW (Kyle et al., 2015). There was
also a correlation of HGS with whole-body IR and
PhA, which was even stronger with the corresponding
upper-limb values. These findings were further sup-
ported by the fact that in multiple regression analysis
BI indexes along with IRs or PhAs were independent
predictors of HGS, whereas gender and age were not.
5 CONCLUSIONS
In conclusion, HGS is clearly associated with BI in-
dexes (marker of FFM), IR and PhA (markers of the
anatomical structure of the muscle).This study gives
information about the use of HGS and raw BIA vari-
ables in the second decade of life. Further studies are
needed to evaluate the reliability and effectiveness of
such approach to assess nutritional status in children
and adolescents.
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