Association between Handgrip Strength and Raw BIA Variables in

Adolescents Aged 14-17 Years

Paola Alicante

, Ada Di Gregorio

, Anna Maria Sacco

, Fabiana Monfrecola

Luca Scalfi

and Giuliana Valerio

Department of Public Health, Federico II University of Naples, Via S. Pansini 5, Naples, Italy

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

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 14–17 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

Weight (kg)

65.8

±10.6

57.3

±8.0

Stature (cm)

171.8

±7.3

160.8

±5.6

BMI-SDS

+0.57

±0.90

+0.38

±0.86

FFM (kg)

54.2

±7.4

42.1

±4.1

FM (kg)

11.5

±5.9

15.2

±6.0

FM (%)

16.8

±7.1

25.8

±7.6

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

/kHz)

frequency of measure

Male

adolescents

Female

adolescents

5 kHz

49.6

±8.0

37.6

±5.4

50 kHz

57.4

±10.2

42.9

±6.7

250 kHz

66.9

±12.2

49.9

±7.9

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

Whole body

0.745

±0.027

0.755

±0.022

Upper limbs

0.756

±0.028

0.770

±0.021

Lower limbs

0.741

±0.032

0.752

±0.030

Phase angle (degrees)

Whole body

6.82

±0.85

6.50

±0.80

Upper limbs

5.16

±0.90

4.57

±0.72

Lower limbs

9.21

±1.22

8.90

±1.19

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

Preferred limb

35.9

±10.4

28.0

±7.3

Non-preferred limb

34.0

±10.3

26.5

±7.4

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)

whole

body

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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