RESEARCH ARTICLE
Strong or Weak Handgrip? Normative
Reference Values for the German Population
across the Life Course Stratified by Sex, Age,
and Body Height
Nadia Steiber
1,2
*
1 Wittgenstein Centre for Demography and Global Human Capital (IIASA, VID/O
¨
AW, WU), International
Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria, 2 Department of Economic Sociology,
University of Vienna, Vienna, Austria
*
steiber@iiasa.ac.at
Abstract
Handgrip strength is an important biomarker of healthy ageing and a powerful predictor of
future morbidity and mortality both in younger and older populations. Therefore, the mea-
surement of handgrip strength is increasingly used as a simple but efficient screening tool
for health vulnerability. This study presents normative reference values for handgrip
strength in Germany for use in research and clinical practice. It is the first study to provide
normative data across the life course that is stratified by sex, age, and body height. The
study used a nationally representative sample of test participants ages 17–90. It was based
on pooled data from five waves of the German Socio-Economic Panel (2006–2014) and
involved a total of 11,790 persons living in Germany (providing 25,285 observations).
Handgrip strength was measured with a Smedley dynamometer. Results showed that peak
mean values of handgrip strength are reached in men’s and women’s 30s and 40s after
which handgrip strength declines in linear fashion with age. Following published recom-
mendations, the study used a cut-off at 2 SD below the sex-specific peak mean value
across the life course to define a ‘weak grip’. Less than 10% of women and men aged 65–
69 were classified as weak according to this definition, shares increasing to about half of
the population aged 80–90. Based on survival analysis that linked handgrip strength to a
relevant outcome, however, a ‘critically weak grip’ that warrants further examination was
estimated to commence already at 1 SD below the group-specific mean value.
Introduction
The strength of a person’s handgrip measured with a dynamometer has come to be widely rec-
ommended as a simple but valid measure of overall muscle strength [
1] and a central marker for
the onset of sarcopenia [
2], i.e., the age-associated reduction of muscle function and strength
from age 50 onwards [3]. Low handgrip strength (abbreviation: 'HGS' in the following) tends to
PLOS ONE | DOI:10.1371/journal.pone.0163917 October 4, 2016 1 / 14
a11111
OPEN ACCESS
Citation: Steiber N (2016) Strong or Weak
Handgrip? Normative Reference Values for the
German Population across the Life Course
Stratified by Sex, Age, and Body Height. PLoS ONE
11(10): e0163917. doi:10.1371/journal.
pone.0163917
Editor: Stefan Kiechl, Medizinische Universitat
Innsbruck, AUSTRIA
Received: July 5, 2016
Accepted: September 17, 2016
Published: October 4, 2016
Copyright: © 2016 Nadia Steiber. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which
permits unrestricted use, distribution, and
reproduction in any medium, provided the original
author and source are credited.
Data Availability Statement: Data from the
German Socio-Economic Panel (SOEP) are made
available for scientific research by the German
Institute for Economic Research (DIW). Contact:
soepmail@diw.de.
Funding: The research leading to these results has
received funding from the European Research
Council under the European Union’s Seventh
Framework Programme (FP7/2007–2013)/ERC
grant agreement no ERC2012-AdG 323947-Re-
Ageing. The funders had no role in study design,
data collection or analysis.
be associated with functional limitations and it is a powerful predictor of future disability, physi-
cal health problems, and cognitive decline [
4–6]. Low HGS was in fact found to be a better pre-
dictor of mortality than chronological age and systolic blood pressure [7–9]. For these reasons,
gerontologists have suggested to measure HGS in clinical practice to allow for an early detection
of a decline in muscle mass associated with morbidity and mortality risks [9,10]. The measure-
ment of HGS is a prime candidate for use in routine medical exams given the simplicity and low
cost at which it helps to assess patients’ muscular fitness [
2].
The measurement of HGS has been proposed as a key component of frailty phenotypes and
it was also suggested as a central biomarker of healthy ageing [
7]. For these reasons, HGS is
measured in a great number of ‘ageing studies’ such as the US Health and Retirement Study
(HRS), the Survey of Health, Ageing, and Retirement in Europe (SHARE), and the English
Longitudinal Survey of Ageing (ELSA). The fact that most surveys that include measures of
HGS only cover the population aged 50 and over limits life course research on HGS. Studies
show that health-related behaviours such as physical activity in mid-life predict HGS at older
ages [11]. Moreover, HGS in early old age (ages 56–68) has been shown to be associated with
the probability of extreme longevity [
12]. Much less is known about levels of HGS earlier in life
and its implications for future outcomes. There is some evidence that low muscle strength
among school-aged youth is associated with cardiovascular and metabolic risk factors [
13],
supporting the view that routine screening of muscle strength should not be restricted to older
ages and that reference values across the life course are needed.
The aim of this study is to provide normative reference values for HGS that allow for a com-
parison of HGS measurements in the clinical context and in other scientific studies with values
that can be considered normal at certain ages. The reference values are measured from a
healthy reference population. Since HGS measurements show a great deal of variation across
geographical regions and national contexts [
14–16], it is important to have region-specific ref-
erence values. In contrast to much of the previous work that tended to be based on small and/
or non-representative convenience samples, this study is based on a large random sample of
test participants that is nationally representative. The presented analyses are based on pooled
data from five survey waves of the German Socio-EconomicPanel (2006–2014) that provide
more than 25 thousand measurements of HGS from test participants ages 17–90.
This study is among the first to provide normative data across the life course (for young,
middle-aged, and older adults)—the very first studies providing life course data have recently
been presented by Dodds et al. [
17] for the British context and by Peterson and Krishnan [18]
for the US (see also [
19]). This study is the first to provide such reference values for Germany
and it is the first to provide reference values across the life course that are not only stratified by
sex and age but also for body height. Prior studies have in part normalized grip strength for body
height or body weight [
18], yet in most cases normative reference values are not presented for
different population groups defined along such anthropometric measures. However, given the
substantial share of the variance in HGS explained by body height (over and above sex and age),
it is clearly important to stratify normative reference values for participants’ body height [
20].
Prior Work
A descriptive review of available studies providing reference values for HGS measurement
shows that most of them draw on small, non-representative convenience samples of test partic-
ipants (see
S1 Table). Only three prior studies have presented nationally representative refer-
ence values covering the whole life course–one for the British context [
17] and two for the US
American context ([
18,19], both using the same source of data). The studies provide similar
results, showing that among men peak mean values of HGS of around 49–52 kg are reached in
Handgrip Strength: Normative Reference Values for the German Population
PLOS ONE | DOI:10.1371/journal.pone.0163917 October 4, 2016 2 / 14
Competing Interests: The authors have declared
that no competing interests exist.
the fourth decade of life, whereas women reach their peak value of about 31 kg on average in
the third or fourth decade of life. In the seventh decade of life, mean values drop to around 41–
42 kg among men and to 25–26 kg among women (see Panel A of
S1 Table).
Other studies presenting reference values for broad age ranges (covering larger parts of the
life course, see Panel B of S1 Table) are typically based on small samples that are not represen-
tative of the country’s population. Many of the studies draw on convenience samples recruited
from various locations such as hospitals, sports clubs, universities, senior residences, or shop-
ping malls [
21–25]. Moreover, all of these studies are restricted to small sets of test participants
at each given sex and age (see also [
26]). Other studies are based on regional data [21,22,27–29]
or on data collected in a diverse set of countries [
30]. Despite methodological limitations, these
studies do not tend to show radically different results compared to those from the nationally
representative studies (cf. Panel A of
S1 Table). Based on a convenience sample of 720 partici-
pants collected in the US, Peters and colleagues [24] show peak mean values of 49 kg for men
and 29 kg for women, values dropping in the seventh decade of life to 43 kg for men and 25 kg
for women. These results are remarkably close to those reported by Perna et al. [
19] drawing
on the representative National Health and Nutrition Examination Study (NHANES). Refer-
ence values from the North West Adelaide Health Study [
29] and from a Health Survey in Rio
de Janeiro [
28] show somewhat lower values for the respective regions of Australia and Brazil
(peak mean values of 47 kg for men in both studies; a decline in men’s seventh decade of life to
40 kg in Adelaide and to 37 kg in Rio). Comparatively higher peak values are shown by studies
drawing on convenience samples from German-speaking regions and Norway (e.g., peak mean
values of 54 kg for Bavarian men, 56 kg for German-speaking Swiss men, and 58 kg for Norwe-
gian men). The values for the seventh decade of life in these studies were also somewhat higher
than those reported by the nationally representative studies for Britain and the US, i.e., drop-
ping to 45 kg for Bavarian men, 43 kg for German-speaking Swiss and Norwegian men
[
22,23,25]. Finally, a study of two cities near Madrid, Spain, suggests that mean values drop to
38 kg among men in their 60s. Such national comparisons appear to corroborate prior research
showing that handgrip tends to be stronger in Northern and Continental European countries
than in Southern Europe [
15]. More robust conclusions can only be drawn based on nationally
representative data. Studies discussed in Panel B of
S1 Table generally provide insufficient sam-
ple sizes for subgroups defined by sex and age and only allow for tentative conclusions.
Compared to the studies presented in Panel B, studies that do not provide a life course per-
spective but that are based on sufficient sample sizes for older age-groups (see Panel C of
S1
Table
) are of greater value for robust inter-study comparisons. A medium-scale study of the
community-dwelling Japanese population aged 60 and above [
31] estimates an average HGS of
38 kg for men aged 65 and of 32 kg for men aged 75, and thus values that are somewhat lower
than those reported in studies of Caucasian populations living in Britain, the US, or Northern
Europe (for regional studies on Japan see also [
32,33]). A study on the Swedish province of
Uppsala, for instance, suggests an average HGS of 41 kg for men aged 74–76. The commonly
found lower HGS among Asian compared to Caucasian men, however, does not appear to
extend to women. Aoyagi and colleagues [34] compare Japanese women living in Japan aged
65–69 with Japanese and Caucasian women living in the US in the same age group. They find
the comparatively highest mean HGS in the native Japanese sample.
Finally, three studies could be identified that provide reference values for certain population
groups that are not only stratified by age and sex but also by body height (see Panel D in
S1
Table
). None of these studies provide reference values across the life course. The largest of
these studies presents values for the United Kingdom, drawing on data from the UK Biobank,
and covers the age range 39–73 [
20]. The second study covers the Danish population aged 45
and above, using data from three nation-wide population-based surveys [35]. And the third
Handgrip Strength: Normative Reference Values for the German Population
PLOS ONE | DOI:10.1371/journal.pone.0163917 October 4, 2016 3 / 14
one draws on data representative of the community-dwelling Irish population aged 50–85 [36].
The studies corroborate the view that it is important to account for the height of test partici-
pants when evaluating their HGS against some reference value. The Irish study suggests, for
instance, that men aged 65 have an average HGS of 34 kg if they are less tall than 173 cm and
of 38 kg if taller. The British and the Danish studies were able to differentiate more than two
height groups, showing that average HGS increases by 2–4 kg for each 10 cm of body height
(with variations in the relation between HGS and body height by age).
To sum up, published normative data for HGS are available from many countries. Typically,
reference values are provided for different age and sex subgroups, whereas only a handful of
studies provide reference values for subgroups defined also along the lines of body height. The
majority of available studies furthermore pertain to a limited age range, whereas only a small
set of studies provide reference values for comprehensive age ranges that cover a large part of
the life course. The few studies taking a life course perspective report mean or median values of
HGS for different sex and age groups and show a peak of HGS in the fourth decade of life fol-
lowed by a gradual decline in HGS with age—for both sexes. Although prior evidence suggests
that normative values would need to be stratified not only for age and sex but also for body
height [
20,36], to date none of the available life course studies provides reference values for
height subgroups. This is the aim of the present study, i.e., to provide reference values for a
comprehensive age range (17–90) and based on sufficient samples sizes for each age group and
sex, to provide values for height subgroups. Many of the available studies (but by far not all)
exclude persons with health limitations such as arthritis, heart conditions, inflammatory or
neurological diseases. There is, however, no standard procedure used to construct a healthy ref-
erence population. At all events, all of the available studies are naturally restricted to test partici-
pants who are in a state of health that allows them to take part in the study and to have their
HGS measured with a dynamometer. This typically excludes the institutionalized population.
The average health among test participants will thus be somewhat better compared to the gen-
eral population.
Data and Methods
German Socio-Economic Panel
This study uses anonymized secondary data, collected by the German Institute for Economic
Research (DIW). The data derive from the German Socio-Economic Panel (SOEP), a house-
hold panel study providing representative data for the German population since 1984. The
SOEP is approved as being in accordance with the standards of the Federal Republic of Ger-
many for lawful data protection. The survey ethics are monitored by an independent advisory
board at the DIW. SOEP data are available free of charge as scientific use files.
In 2006 when HGS was first measured, a random subsample of 5,528 individuals out of
32,304 survey respondents was selected to be assessed for HGS. In 2008, the measure was
repeated for the majority of the 2006 test participants (longitudinal stability of 76%) and from
1,437 individuals HGS was measured for the first time in 2008 [
37]. HGS was again measured
in 2010, 2012, and 2014; including both repeat testing (longitudinal sample providing HGS
measures at more than one age) and testing on refresher samples measured for the first time in
these years. The HGS measurement included more than 5,000 participants in each of the four
measurement years (annual response rates ranging between 95% and 97%).
Sample
The sample is restricted to participants ages 17–90 (due to small sample sizes outside this age
range). For details on sample sizes in the chosen age range in the five measurement years, see
Handgrip Strength: Normative Reference Values for the German Population
PLOS ONE | DOI:10.1371/journal.pone.0163917 October 4, 2016 4 / 14
S2 Table. In terms of anthropometric measures, the sample is restricted to men who are
between 160 and 200 centimetres tall and to women with a body height between 150 and 184
centimetres (i.e., excluding 1% of participants). Moreover, it excludes 222 outliers, identified
from sex-specific regressions that model HGS as a function of age and body height in linear
and quadratic form. Those with standardized residuals of above +/-3 SD are removed from the
sample (0.8% of participants). In the aim to provide results for a healthy reference population,
the sample is restricted to those able to participate in the HGS test and attaining a value of at
least 10 kg. This threshold can easily be met by all reasonably healthy persons even at higher
ages (e.g., less than 2% of participants aged 80–90 attain values below 10 kg). Overall, the lower
bound on the HGS test result of 10 kg excludes 0.09% of measurements. Finally, the sample
excludes those who score in the lowest 5% of the Physical Component Summary Scale (PCS) of
the SF-12 module in the SOEP which measures functional health and well-being based on
twelve questions. The SF-12 is considered a quasi-objective measure of health [
38,39]. It covers
eight health domains that are summarized in two dimensions: physical health (PCS) and men-
tal health (MCS). The PCS accounts for physical functioning, role limitations due to physical
health problems, bodily pain, and general health perceptions. The PCS score is z-standardized
to a mean value of 50 and a SD of 10 (the cut-off value to define the lowest 5% of the PCS is
30). The final sample for analysis involves 25,285 observations.
Handgrip strength
Handgrip strength in kilogrammes is measured with the Smedley S DynamometerTMM Tokio
100kg. Prior research suggests that different dynamometer types and brands produce similar
results, i.e., reference values are robust to the dynamometer type used [
17], and that values
taken with a Smedley dynamometer very strongly correlate with those taken with the com-
monly used Jamar dynamometer [40]. The examination procedure in SOEP foresees that two
measures of HGS are taken from each hand. Following published recommendations [
1,37], the
maximum value achieved with either hand is used as a summary measure of a person’s isomet-
ric strength of the hand and forearm muscles. This is a common choice of summary measure
in prior research (cf.
S1 Table), yet it is worth mentioning that studies show similar results irre-
spective of whether they use average or maximum values achieved in multiple trials [
41].
Statistical analysis
For the statistical analyses, data from five waves of the SOEP are pooled, resulting in 25,285
HGS measurements (from 11,790 persons). Following [
17], all available data is used, including
values for individuals who had their HGS measured at more than one age. Results are weighted.
In a first step, simple means (M), standard deviations (SD), and median values (p50) are pre-
sented for 14 age groups (
S3 Table). Based on OLS regression analysis (with age, height and the
variables’ square terms as predictors of HGS), sex-specific life course profiles of HGS are esti-
mated and graphically presented. These profiles do not yet account for body height and thus
allow for a definition of peak mean values for women and men that can be compared with
prior studies.
In a second step, age-specific ‘height discount factors’ are calculated based on OLS regres-
sions of HGS on age and body height (and its squared term). To allow for age-specific height
stratification, separate regressions are carried out for different age groups (17–24, 25–35, 45–
54, 55–64, 65–74, 75–84, 85–90). These regressions are then used to estimate mean HGS across
seven height groups (within each of the 14 age groups). The results are presented as sex-specific
reference values, stratified by age and body height.
Handgrip Strength: Normative Reference Values for the German Population
PLOS ONE | DOI:10.1371/journal.pone.0163917 October 4, 2016 5 / 14