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Muscular strength in male adolescents and premature
death: cohort study of one million participants
OPEN ACCESS
Francisco B Ortega research associate
1 2 3
, Karri Silventoinen research associate
4
, Per Tynelius
statistician
5
, Finn Rasmussen professor
5
1
Department of Physical Education and Sport, School of Sport Sciences, University of Granada, Granada, Spain;
2
Department of Biosciences and
Nutrition at NOVUM, Karolinska Institutet, Huddinge, Stockholm, Sweden;
3
Department of Medical Physiology, School of Medicine, University of
Granada;
4
Population Research Unit, Department of Social Research, University of Helsinki, Helsinki, Finland;
5
Child and Adolescent Public Health
Epidemiology Group, Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden
Abstract
Objectives To explore the extent to which muscular strength in
adolescence is associated with all cause and cause specific premature
mortality (<55 years).
Design Prospective cohort study.
Setting Sweden.
Participants 1 142 599 Swedish male adolescents aged 16-19 years
were followed over a period of 24 years.
Main outcome measures Baseline examinations included knee
extension, handgrip, and elbow flexion strength tests, as well as
measures of diastolic and systolic blood pressure and body mass index.
Cox regression was used to estimate hazard ratios for mortality according
to muscular strength categories (tenths).
Results During a median follow-up period of 24 years, 26 145
participants died. Suicide was a more frequent cause of death in young
adulthood (22.3%) than was cardiovascular diseases (7.8%) or cancer
(14.9%). High muscular strength in adolescence, as assessed by knee
extension and handgrip tests, was associated with a 20-35% lower risk
of premature mortality due to any cause or cardiovascular disease,
independently of body mass index or blood pressure; no association
was observed with mortality due to cancer. Stronger adolescents had a
20-30% lower risk of death from suicide and were 15-65% less likely to
have any psychiatric diagnosis (such as schizophrenia and mood
disorders). Adolescents in the lowest tenth of muscular strength showed
by far the highest risk of mortality for different causes. All cause mortality
rates (per 100 000 person years) ranged between 122.3 and 86.9 for
the weakest and strongest adolescents; corresponding figures were 9.5
and 5.6 for mortality due to cardiovascular diseases and 24.6 and 16.9
for mortality due to suicide.
Conclusions Low muscular strength in adolescents is an emerging risk
factor for major causes of death in young adulthood, such as suicide
and cardiovascular diseases. The effect size observed for all cause
mortality was equivalent to that for well established risk factors such as
elevated body mass index or blood pressure.
Introduction
Knowledge about different risk factors at early stages of life for
later premature mortality is needed for disease prevention and
early treatment. In addition to traditional risk factors, such as
obesity and hypertension, a low cardiorespiratory fitness level
during middle or older ages has been proposed as a powerful
predictor of mortality.
1 2
Another important health related
component of fitness is muscular strength, which has been
shown to be positively related to cardiorespiratory fitness.
3
Although muscular strength has received far less attention than
cardiorespiratory fitness, recent studies support the hypothesis
that low muscular strength in adulthood also predicts all cause
mortality, as well as mortality due to cardiovascular disease and
cancer in healthy and diseased people.
4-13
Whether muscular
strength in childhood, adolescence, or both is a predictor of
mortality is unknown. Mortality rates in young adulthood are
very low in developed counties; consequently, large samples
sizes and long follow-up periods are needed to accumulate
enough cases to ensure appropriate statistical power in the
analyses.
Suicide is the leading cause of death in young adults (25-44
years old) and a major public health concern in developed and
developing countries.
14 15
Identification of early modifiable risk
factors for suicide is therefore important for the design of
successful strategies for suicide prevention.
In this study, we followed up more than one million male
adolescents (16-19 years of age) recruited from the Swedish
military conscription register to explore the extent to which
Correspondence to: F Rasmussen Finn.Rasmussen@ki.se
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Research
RESEARCH
muscular strength in adolescence is associated with all cause
premature mortality (defined as death before 55 years of age),
as well as cause specific premature mortality due to
cardiovascular disease (coronary heart disease and stroke) and
cancer. A second major aim was to study muscular strength in
relation to mortality due to suicide. To obtain meaningful
information about the clinical relevance of our results, we
compared the effect sizes observed for associations between
muscular strength and premature mortality with those for
traditional disease risk factors such as body mass index and
blood pressure.
16-18
The associations of body mass index and
blood pressure with mortality have previously been examined
in depth in this population,
17 18
and they are included in this
study only for comparison purposes.
Methods
Study sample and design
We used data from the Swedish military conscription register
for male adolescents born in Sweden between 1951 and 1976,
according to the multi-generation register.
19 20
Conscription
examinations are mandatory by law for all young male Swedish
citizens, and they predate active military service; that is, they
are also done for boys who do not later enter military service.
21
During the years covered by this study, only boys with severe
handicap or a chronic disease were exempted from the
conscription. A total of 1 194 359 participants with valid data
on age at conscription were available. Inclusion criteria were
age 19 years or less (98.4% of the original sample) and
availability of valid data on the main exposures (three strength
tests, body mass index, and blood pressure), main confounders
(year of birth, conscription age, conscription office), and main
study outcomes (mortality). We defined premature death as
death before the age of 55 years, following criteria used in
previous studies on premature death.
16
The entire study sample
met these criteria. To minimise the risk of reverse causality, we
excluded participants with less than one year of follow-up from
the analyses (n=985).
13 22
Finally, we excluded those with
extreme values for height (valid range 150-210 cm), weight
(valid range 40-150 kg), body mass index (valid range 15-60),
or diastolic and systolic blood pressure (valid ranges 40-100
mm Hg and 100-180 mm Hg) (n=1669). A total of 1 142 599
male adolescents (95.8% of the sample) aged 16 to 19 years
(mean age 18.3 (SD 0.5) years) met all the aforementioned
criteria and were therefore included in main analyses (see
appendix fig A). The Centers for Disease Control and Prevention
defines the age range for adolescence as 10-19 years.
Accordingly, the baseline period studied here is considered late
adolescence.
Baseline examination
During the conscription (baseline) examination, knee extension
strength, handgrip strength, elbow flexion strength, diastolic
and systolic blood pressure, and height and weight were
measured, as previously described.
18 23
These muscular strength
tests have been shown to have high reliability in young men
(r=0.88-0.98).
24
The Swedish Defence Recruitment Agency
regarded the exact measurement protocol to be confidential
information and did not reveal it to us. However, we observed
in preliminary analyses that no systematic differences existed
in the mean values of the measures between conscription offices,
suggesting that a uniform protocol was used. The values of
elbow flexion, handgrip, and knee extension strength in these
data were similar to values in a previous study of young Finnish
men, supporting the notion that standard protocols were used.
24
We calculated body mass index as weight (kg) divided by
squared height (m). Parental socioeconomic position in
childhood came from population and housing censuses 1960-80
and parental level of education from the 1970 census. We
retrieved participants’ own highest achieved educational level
from the educational register 1990-2004 (see sample sizes and
study categories in appendix table A).
25
Follow-up and ascertainment of mortality
We calculated the follow-up period as from the age of
conscription until the earliest of three possible events: death,
date of emigration, or end of follow-up (31 December 2006),
whichever came first. The median follow-up period was 24.2
(range 1.0-37.3) years.
We used the cause of death register,
26
and we categorised the
underlying cause of death according to the eighth, ninth, and
tenth revisions of the Swedish version of the international
classification of diseases as coronary heart disease (410-414 for
ICD-8 and ICD-9; I20-I25 for ICD-10), stroke (430-438, 344
for ICD-8, 430-438, 342, 344 for ICD-9; I60-I66, G45 for
ICD-10), cancer (140-239 for ICD-8 and ICD-9; C00-D48 for
ICD-10), suicide (E950-E959, E980-E989 for ICD-8 and ICD-9;
X60-X64, Y10-Y34 for ICD-10), and non-intentional accidents
(800-929 for ICD-8 and ICD-9; V01-X59 for ICD-10), as
previously described.
18 25 27-29
Information about causes of death
was available until 31 December 2004.
Statistical analysis
We used Cox proportional hazards regression to estimate hazard
ratios and 95% confidence intervals for mortality according to
exposure categories (tenths) of the three muscular strength tests
separately. We did similar analyses for body mass index and
blood pressure. We set the lowest tenth for muscular strength
variables and the highest tenth for body mass index and blood
pressure as reference groups, so that the hazard ratios would
mostly range between 0 and 1 for all the exposures, allowing
easier comparison among exposures. The main outcomes were
all cause mortality and mortality due to cardiovascular disease,
cancer, and suicide. We adjusted all the models for year of birth,
conscription age, and conscription office. Additionally, we used
adjusted models for simultaneous analysis of significant
predictors—that is, muscular strength (knee extension, handgrip,
or elbow flexion), body mass index, and blood pressure
(diastolic or systolic). We used SPSS statistical software, version
19.0.0, for all statistical analyses.
Results
Appendix table A shows baseline characteristics of the whole
study cohort, and appendix table B shows body mass index and
blood pressure stratified by categories of muscular strength.
Appendix fig B shows the distribution of muscular strength
variables. Over the follow-up period (24.2 years), 26 145 (2.3%)
participants died. Information on underlying causes of death
was available for 22 883 participants. Among these 22 883
deaths, 1254 (5.5%) were caused by coronary heart disease, 526
(2.3%) by stroke, 3425 (14.9%) by any type of cancer, 5100
(22.3%) by suicide, and 5921 (25.9%) by non-intentional
accidents. We categorised the remaining deaths (6657; 29.1%)
as other causes of mortality. A combination of coronary heart
disease and strokes (that is, cardiovascular disease) resulted in
1780 (7.8%) deaths. Figures 1⇓, 2⇓, 3⇓, and 4⇓ show hazard
ratios and 95% confidence intervals for all cause mortality and
mortality due to cardiovascular disease, suicide, and cancer.
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RESEARCH
All cause mortality
Higher levels of muscular strength were significantly associated
with lower risk of all cause mortality. The association was
stronger for knee extension and handgrip strength than for elbow
flexion strength (fig 1⇓). Compared with the weakest group
(first tenth), higher levels (second, third, and fourth tenths) of
muscular strength were monotonically associated with
progressively reduced mortality risk. From the fourth tenth on,
a plateau was achieved, with an approximate 20% risk reduction
for premature mortality for knee extension and handgrip—that
is, hazard ratios ranged from 0.78 to 0.84 and confidence
intervals from 0.74 to 0.88. We saw a similar effect size (~20%
risk reduction) for body mass index and diastolic blood pressure,
whereas the effect of systolic blood pressure was weaker than
that of diastolic blood pressure (fig 1⇓). Mutually adjusted
analyses showed that muscular strength (knee extension or
handgrip), body mass index, and diastolic blood pressure were
independently associated with premature all cause death (fig
5⇓). Analyses stratified by body mass index categories showed
that muscular strength was inversely associated with all cause
mortality within all body mass index categories—that is,
underweight, normal weight, overweight, and obese adolescents
(fig 6⇓). All cause mortality rates per 100 000 person years were
122.3 for adolescents with very low muscular strength, 98.9 for
those with low to middle muscular strength, and 86.9 for those
with and middle to very high muscular strength, as measured
by the knee extension test (appendix table C). The corresponding
rates for handgrip muscular strength were 114.5, 96.5, and 90.9
(appendix table C).
Cardiovascular disease mortality
Body mass index and blood pressure (both diastolic and systolic)
were strongly associated with premature mortality due to
cardiovascular disease (fig 2⇓). Muscular strength was not
clearly associated with premature mortality due to cardiovascular
disease in Cox models adjusted only for year of birth, age at
conscription, and conscription office (fig 2⇓), but it became
significantly associated with cardiovascular disease mortality
after additional adjustments for body mass index and diastolic
blood pressure (see knee extension and handgrip strength in fig
5⇓). The risk reduction was approximately 35% in high muscular
strength groups, 60-70% in low body mass index groups, and
35-45% in low diastolic blood pressure groups, compared with
the reference groups. We saw similar patterns when we did the
analyses separately for coronary heart disease and stroke (data
not shown). Mortality rates per 100 000 person years due to
cardiovascular disease were 9.5 for adolescents with very low
muscular strength, 7.3 for those with low to middle muscular
strength, and 5.6 for those with middle to very high muscular
strength, as measured by the knee extension test (appendix table
C). The corresponding rates for handgrip muscular strength
were 8.3, 7.3, and 5.6 (appendix table C).
Suicide mortality
High muscular strength (knee extension and handgrip) was
associated with a 20-30% lower risk of death from suicide (fig
3⇓). We found a monotone and inverse association between
body mass index and mortality due to suicide, whereas no clear
association was apparent between systolic and diastolic blood
pressure and suicide, as previously reported by our group.
30
The
results persisted in the fully adjusted model (fig 5⇓). Mortality
rates per 100 000 person years due to suicide were 24.6 for
adolescents with very low muscular strength, 20.3 for those
with low to middle muscular strength, and 16.9 for those with
middle to very high muscular strength, as measured by the knee
extension test (appendix table C). The corresponding rates for
handgrip muscular strength were 22.4, 19.7, and 17.9 (appendix
table C).
Cancer mortality
Body mass index was the only significant predictor of premature
mortality due to cancer (fig 4⇓), with a risk reduction of 25-35%
in participants with low body mass index compared with those
with high body mass index. The results persisted after mutual
adjustment for the other exposures (appendix fig E).
Additional analyses
Appendix figures C and D show hazard ratios for mortality due
to non-intentional accidents or other causes, to provide the full
spectrum of cause specific mortality, but we do not discuss this
further, as it is outside the scope of this study. In exploratory
analyses, we observed that adolescents with a higher muscular
strength level were 15-65% less likely to have any psychiatric
diagnosis (that is, schizophrenia, other non-affective psychosis,
mood disorders, neurotic and somatoform disorders, adjustment
disorders, personality disorders, or alcohol related disorders,
according to ICD-8/ICD-9 or ICD-10, as previously described
31
)
at baseline (cross sectional association) and years later
(longitudinal association) (see appendix fig F). We did this
analysis after excluding participants with a psychiatric diagnosis
before conscription. When we additionally adjusted the
association between muscular strength and mortality due to
suicide for psychiatric diagnoses either at baseline or years later,
the association was attenuated and became non-significant (data
not shown). Overall, little or no effect was apparent after further
adjustment for socioeconomic factors (data not shown).
Discussion
Three major findings relevant for clinical practice and public
health monitoring emerged from this prospective study. Firstly,
muscular strength in adolescence, as assessed by handgrip and
knee extension tests, is strongly associated with premature death
from any cause, independently of body mass index or diastolic
blood pressure. The effect sizes of these associations are similar
to those of classic risk factors such as body mass index and
blood pressure. Secondly, muscular strength is also associated
with premature death from cardiovascular disease, independently
of body mass index and blood pressure. Thirdly, stronger
adolescents have a lower risk of mortality due to suicide,
whereas no association is apparent with mortality due to cancer.
After doing several systematic reviews and validation studies
(as part of the ALPHA project: www.thealphaproject.net), we
concluded that the handgrip test and tests of lower body muscle
strength (jump tests, leg extension) are the most reliable, valid,
and health related muscular strength tests.
32
This could at least
partially explain why the associations were stronger for handgrip
and knee extension strength than for elbow flexion strength.
All cause mortality and cardiovascular
disease mortality
Previous studies in adults or older adults have supported an
association between muscular fitness and all cause mortality,
cardiovascular disease mortality, or both.
4-13
Our study provides
new evidence for the importance of muscular strength in
adolescence as predictor of premature mortality due to any cause
or cardiovascular disease. In addition, our results suggest that
the lowest tenth of population distribution of muscular strength
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RESEARCH
in late adolescence has the greatest risk of all cause mortality
in late life. Higher levels of strength are associated with
additional risk reduction, and the risk reduction levels off close
to the median (fourth to fifth tenths). This indicates that people
with a muscular strength level equal to or higher than the
population average have the same 20% risk reduction in all
cause mortality, suggesting the need to target those with very
low strength. Likewise, results from other cohort studies have
reported similar reductions in the risk of mortality in men with
middle versus high muscular strength,
11
suggesting that having
high levels of muscular strength does not provide additional
“protection” against death compared with middle levels of
muscular strength. The findings of this study also suggest that
muscular strength in adolescence is as important as body mass
index or blood pressure in terms of all cause mortality, whereas
body mass index has a greater role than muscular strength or
blood pressure in terms of mortality due to cardiovascular
disease.
Suicide mortality
Unfortunately, we cannot discuss our results in relation to
previous literature, as we have not found studies examining the
association between muscular strength and suicide or between
muscular strength and later psychiatric diagnosis. A few
investigations, however, have focused on another component
of physical fitness (that is, cardiorespiratory fitness) and suggest
that high cardiorespiratory fitness in adulthood predicts a lower
risk of depression, both in cross sectional and longitudinal
studies.
33 34
Likewise, adolescents with a lower cardiorespiratory
fitness level are more likely to have a diagnosis of psychosis or
schizophrenia.
35-37
Taken together, these findings support a link
between cardiorespiratory fitness and mental health, which could
in turn be related to suicidal behaviour.
In addition, we observed that adolescents with a higher muscular
strength were less likely to have a psychiatric diagnosis at
baseline and years later, which seemed to partly explain the
lower risk of premature mortality due to suicide seen in this
study. These findings suggest that physically weaker people
might be more mentally vulnerable. Outlining a biological
explanation for this association that could be reproduced in
other studies is difficult. Reverse causation might partially
explain this association. People with more mental problems
(such as depression or schizophrenia) might be less likely to
become involved in any social activity, including physical
activities, which in turn would result in decreased physical
fitness and lower muscular strength due to inactivity. On the
other hand, depression and many other psychiatric disorders are
highly related with a poor self concept and self esteem.
38-41
Likewise, low physical fitness in general, and low muscular
fitness in particular, has been found to be closely related to
lower self concept/self esteem.
42
Therefore, we could reasonably
hypothesise that people with a very low muscular fitness have
a worse self concept/self esteem, which may put them at higher
risk of psychiatric disorders and suicide. This hypothesis is
supported by several studies.
43 44
Cancer mortality
The available literature is contradictory with respect to mortality
due to cancer. Although some authors have observed an
association between muscular strength and mortality due to
cancer,
6 11
others have found no association.
5 10
Muscular strength
was not associated with premature cancer mortality in our study.
The large sample size in this study, and the resulting high
statistical power of the analyses, strengthens the confidence in
the null hypothesis (that is, no association between muscular
strength and mortality due to cancer).
Limitations
This study is based on conscription data from 1969-94, and no
information is available for female adolescents during this time
period. Although some studies have observed significant effects
in both men and women,
7
most of available literature seems to
supports the notion that low muscular strength might be a
stronger predictor of mortality in men than in women.
4-6 10
This
study is based on muscular strength of male adolescents and
premature mortality among those who came to the conscription
examination; we cannot know to what extent our findings apply
to other populations. Unfortunately, cardiorespiratory fitness
and physical activity data were not available, so we were unable
to examine whether muscular strength is associated with
premature mortality independently of these two factors.
Nevertheless, several studies in adults and elderly people have
reported that muscular strength is associated with mortality after
adjustment for cardiorespiratory fitness or physical activity,
7 11 13
suggesting that this might also be the case among adolescents.
Strengths
We followed more than one million male adolescents for 24
years. The large sample size and high statistical power allowed
us to study cause specific mortality over the whole range of the
distribution of muscular strength. To our best knowledge, this
is the first study that links muscular strength assessed in an
adolescent population with all cause and cause specific mortality
many years later. Only a small study in female adolescents aged
17 years (n=510) has linked cardiorespiratory fitness (the most
studied fitness component) in early ages to all cause mortality.
45
The inverse association between muscular strength and mortality
due to suicide is a novel finding. Availability of information
about psychiatric diagnoses from the conscription examination
and also from psychiatric inpatient care during many years of
follow-up allowed cross sectional and longitudinal analyses,
which shed further light on the association between muscular
strength and mortality due to suicide. Thanks to these data, we
found that the association between muscular strength and
mortality due to suicide seems to be partly mediated by
psychiatric disorders.
Clinical and public health implications
Although several tests of muscular strength are available, the
strongest evidence in relation to mortality has been reported for
the handgrip strength test.
4-10 12
As handgrip strength can be
assessed with good reliability in almost any place without
additional costly equipment, it is a useful tool for clinical
settings and for preventive services in schools and workplaces,
for example. The study of premature mortality is of special
relevance as a result of many years of life lost and also large
productivity losses at the societal level. Although this study
cannot disentangle causal pathways, physical training from
childhood and adolescence seems to be needed. People at
increased risk of long term mortality, because of lower muscular
strength, should be encouraged to engage in exercise
programmes and other forms of physical activity. In appendix
tables D and E, we propose reference values and “healthy”
muscular fitness zones based on the results of this study and
reference values of European adolescents from the HELENA
study.
46
However, we acknowledge that these reference values
are tentative and that further research in younger adolescents
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BMJ 2012;345:e7279 doi: 10.1136/bmj.e7279 (Published 20 November 2012) Page 4 of 12
RESEARCH
and female adolescents is needed before firm conclusions can
be drawn.
Conclusions
This study provides strong evidence that a low level of muscular
strength in late adolescence, as measured by knee extension and
handgrip strength tests, is associated with all cause premature
mortality to a similar extent as classic risk factors such as body
mass index or blood pressure. Muscular strength is also
associated with premature mortality due to cardiovascular
disease but not that due to cancer. Finally, our data suggest that
low muscular strength is associated with an increased risk of
mortality due to suicide, supporting the notion that physically
weaker people might also be mentally more vulnerable. Low
muscular strength should be considered an emerging risk factor
for major causes of death in young adulthood.
We are grateful to Jonatan R Ruiz, Manuel J Castillo, Michael Sjöström,
and Steven Blair’s group for constructive scientific discussions. We are
also indebted to Charlotte Goodrose-Flores for the English revision.
Contributors: FR was responsible for the concept and design of the
study. FR and PT acquired the data. PT created the dataset, and FBO
did the statistical analysis and prepared the first draft of the manuscript.
All authors were involved in further analysis and interpretation of data,
drafting the manuscript, and critical revision of the manuscript for
important intellectual content. They are all guarantors.
Funding: The study was supported by a grant to FR from the Swedish
Research Council (grant 2007-5942). FBO was supported by grants
from the Spanish Ministry of Science and Innovation (RYC-2011-09011).
The funding bodies had no role in the preparation of this manuscript.
Competing interests: All authors have completed the ICMJE uniform
disclosure form at www.icmje.org/coi_disclosure.pdf (available on
request from the corresponding author) and declare: the study was
supported by a grant to FR from the Swedish Research Council, and
FBO was supported by grants from the Spanish Ministry of Science and
Innovation; no financial relationships with any organisations that might
have an interest in the submitted work in the previous three years; no
other relationships or activities that could appear to have influenced the
submitted work.
Ethical approval: The study was approved by the Ethical Review Board,
Stockholm, Sweden.
Data sharing: No additional data available.
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Accepted: 19 October 2012
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BMJ 2012;345:e7279 doi: 10.1136/bmj.e7279 (Published 20 November 2012) Page 5 of 12
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What is already known in this topic
Muscular strength in adulthood is associated with all cause mortality and cardiovascular disease mortality
Whether low muscular strength in adolescence is associated with mortality is unknown; a long follow-up period and very large sample
size would be needed to explore this
A higher cardiorespiratory fitness is associated with better mental health in adults, but whether muscular strength at any age is associated
with future mental health and suicide mortality is unknown
What this study adds
Muscular strength in adolescence, as assessed by knee extension and handgrip tests, was associated with a 20-35% lower risk of all
cause and cardiovascular disease premature mortality (<55 years), independently of body mass index or blood pressure
Stronger adolescents had a 20-30% lower risk of death from suicide and were 15-65% less likely to have any psychiatric diagnosis
(such as schizophrenia and mood disorders)
Adolescents in the lowest tenth of muscular strength showed by far the highest risk of mortality due to different causes
Cite this as: BMJ 2012;345:e7279
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Figures
Fig 1 Hazard ratios (95% CI) for relation of muscular strength, body mass index, and blood pressure with all cause premature
death. Models were adjusted for birth cohort, conscription age, and conscription office (n=1 142 599)
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Fig 2 Hazard ratios (95% CI) for relation of muscular strength, body mass index, and blood pressure with premature death
from cardiovascular disease. Models were adjusted for birth cohort, conscription age, and conscription office (n=1 118 154)
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Fig 3 Hazard ratios (95% CI) for relation of muscular strength, body mass index, and blood pressure with premature death
from suicide. Models were adjusted for birth cohort, conscription age, and conscription office (n=1 121 480)
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Fig 4 Hazard ratios (95% CI) for relation of muscular strength, body mass index, and blood pressure with premature death
from cancer. Models were adjusted for birth cohort, conscription age, and conscription office (n=1 119 790)
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Fig 5 Hazard ratios (95% CI) for relation of muscular strength, body mass index, and blood pressure, mutually adjusted,
with all cause premature death and death from cardiovascular disease and suicide. Models were additionally adjusted for
birth cohort, conscription age, and conscription office
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Fig 6 Hazard ratios (95% CI) for relation of muscular strength with all cause premature death, stratified by body mass index
(BMI) categories. Models were adjusted for birth cohort, conscription age, and conscription office
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BMJ 2012;345:e7279 doi: 10.1136/bmj.e7279 (Published 20 November 2012) Page 12 of 12
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