232  |   
 
Scand J Med Sci Sports. 2019;29:232–239.
wileyonlinelibrary.com/journal/sms
1 
| 
INTRODUCTION
Low cardiorespiratory fitness (VO2max) is a strong indepen-
dent predictor of poor metabolic health and increased risk for 
most non‐communicable diseases, as well as lower sustained, 
work productivity, and shorter life expectancy.1,2 During re-
cent decades, several behavioral and environmental factors 
have changed which may have negatively affected population 
Received: 22 July 2018 | 
Revised: 28 September 2018 | 
Accepted: 12 October 2018
DOI: 10.1111/sms.13328
O R I G I N A L  A R T I C L E
Decline in cardiorespiratory fitness in the Swedish working force 
between 1995 and 2017
Elin Ekblom‐Bak1
 | Örjan Ekblom1
 | Gunnar Andersson2 | Peter Wallin2 |  
Jonas Söderling3 | Erik Hemmingsson1
 | Björn Ekblom1
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original 
work is properly cited.
© 2018 The Authors. Scandinavian Journal of Medicine & Science In Sports Published by John Wiley & Sons Ltd
1Åstrand Laboratory of Work 
Physiology, The Swedish School of Sport 
and Health Sciences, Stockholm, Sweden
2Research Department, HPI Health Profile 
Institute, Danderyd, Sweden
3Department of Medicine, Karolinska 
Institutet, Karolinska University Hospital 
Solna, Stockholm, Sweden
Correspondence
Elin Ekblom‐Bak, The Åstrand Laboratory 
of Work Physiology, The Swedish School 
of Sport and Health Sciences, Stockholm, 
Sweden.
Email: eline@gih.se
Funding information
The study was supported by the Swedish 
Research Council for Health, Working Life 
and Welfare (FORTE, Dnr 2018‐00384), 
and the Swedish Armed Forces grant 
number (AF9220915).
Background: Long‐term trend analyses of cardiorespiratory fitness (VO2max) in the 
general population are limited.
Objectives: To describe trends in VO2max from 1995 to 2017 in the Swedish work-
ing force and to study developments across categories of sex, age, education, and 
geographic regions.
Methods: A total of 354 277 participants (44% women, 18‐74 years) who partici-
pated in a nationwide occupational health service screening between 1995 and 2017 
were included. Changes in standardized mean values of absolute (L/min) and relative 
(mL/min/kg) VO2max, and the proportion with low (<32) relative VO2max are re-
ported. VO2max was estimated using a submaximal cycle test.
Results: Absolute VO2max decreased by −6.7% (−0.19 L/min) in the total popula-
tion. Relative VO2max decreased by −10.8% (−4.2 mL/min/kg) with approximately 
one‐third explained by a simultaneous increase in body mass. Decreases in absolute 
fitness were more pronounced in men vs women (8.7% vs 5.3%), in younger vs older 
(6.5% vs 2.3%), in short (11.4%) vs long (4.5%) education, and in rural vs urban re-
gions (6.5% vs 3.5%), all P < 0.001. The proportions with low VO2max increased 
from 27% to 46% (P < 0.001).
Conclusion: Between 1995 and 2017, there was a steady and pronounced decline in 
mean cardiorespiratory fitness in Swedish adults. Male gender, young age, short edu-
cation, and living in a rural area were predictive of greater reductions. The proportion 
with low cardiorespiratory fitness almost doubled. Given the strong associations be-
tween cardiorespiratory fitness and multiple morbidities and mortality, preventing 
further decreases is a clear public health priority, especially for vulnerable groups.
K E Y W O R D S
aerobic capacity, maximal oxygen consumption, population, secular trend, VO2max
EKBLOM‐BAK Et AL.
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233
EKBLOM‐BAK Et AL.
levels of physical activity (PA) and thereby cardiorespiratory 
fitness.3 Together with an increased prevalence of overweight 
and obesity,4 it is plausible that the level of relative VO2max 
(mL/min/kg) has decreased. However, previous studies of 
secular trends in VO2max are limited to military conscripts5-7 
or smaller samples of the general population,8-10 meaning that 
there is a lack of studies on secular trends in large populations 
of adults. Women are understudied, and with the alarming 
inequality in health and longevity between socioeconomic 
groups11 and an expected significant increase in multi‐mor-
bidity among the older population over the next decades,12 
subgroups analyses are highly clinically relevant.
Health Profile Assessment (HPA) has been carried out in 
occupational health services in Sweden for almost 40 years 
to promote health, collecting data from approximately 40 000 
annual examinations during the last years.13 The combina-
tion of the large amount of HPA performed each year and 
the long‐term use of established and standardized methods in 
occupational health promotion generates a unique database, 
which enables analyses of level of and change in estimated 
VO2max in the Swedish working population over several 
decades.
The primary aim of this paper was to describe secular 
trends in estimated VO2max from a submaximal cycle er-
gometer test between 1995 and 2017 in a large sample of 
the working Swedish population, aged 18 to 74 years, and to 
study potential variations between women and men, different 
age‐groups, educational levels, and regions.
2 
| 
MATERIALS AND METHODS
This study was based on cohort data from the HPA database, 
managed by the HPI Health Profile Institute (Stockholm, 
Sweden), which also is responsible for standardization of 
methods used and education of the HPA coaches since in-
ception. The HPA is an interdisciplinary method13,14 and 
includes an extensive questionnaire, measurements of 
anthropometrics and blood pressure, a submaximal cycle 
test for estimation of VO2max and a person‐centered di-
alogue with an HPA coach. Participation is voluntary, is 
free of charge, and is offered to all employees working for 
a company or organization connected to occupational or 
other health service. From October 1982 until May 2017, 
437 676 participants (18 to 74 year old) with a first‐time 
HPA and providing data on gender, age, and educational 
level were stored in the central database. The annual rate of 
participants was substantially lower in the first years, 1982 
(n = 1) and 1994 (n = 888), compared to the following full 
years, 1995 (n = 1 347) vs 2016 (n = 31 529). To minimize 
influence of uncertainty and variations in the data collection 
procedure, we limited our analyses to 1995‐2017 (n = 436 
126). Of these, 81.2% (n = 354 277) provided valid data of 
estimated VO2max and were included in the analyses. All 
participants provided informed consent prior to data col-
lection. The study was approved by the ethics board at the 
Stockholm Ethics Review Board (Dnr 2015/1864‐31/2 and 
2016/9‐32), and adhered to the Declaration of Helsinki.
2.1 | Estimation of VO2max
Measurement of actual VO2max by a graded test to exhaus-
tion in the general population is limited by numerous factors, 
including health risks in non‐athletic population and de-
pendence on laboratory equipment and expertise. Therefore, 
VO2max was estimated from the standardized Astrand sub-
maximal cycle ergometer test.15 Criterion validity has been 
tested for the Astrand test, showing no systematic bias and 
limited variation in mean difference between estimated and 
directly measured VO2max, mean difference 0.01 L O2/min 
(95% CI −0.10 to 0.11).8,16 All participants were requested 
to refrain from vigorous activity the day before the test, con-
suming a heavy meal 3 hours and smoking/snuff use 1 hour 
before the test, and avoiding stress. The participant cycled on 
a calibrated ergometer at an individually adapted submaxi-
mal work rate for 6 minutes to achieve a steady‐state pulse. 
Using the steady‐state pulse, VO2max was estimated from 
a sex‐specific nomogram, with corresponding age‐correction 
factors, expressed as absolute (L/min) and relative (mL/min/
kg) VO2max.
2.2 | Other measurements
Body mass was assessed with a calibrated scale in light-
weight clothing to the nearest 0.5 kg. Body height was meas-
ured to the nearest 0.5 cm using a wall‐mounted stadiometer. 
Highest educational attainment and place of dwelling (as 
county in Sweden of residence) at the time for the HPA was 
obtained by linking the personal identity number of the par-
ticipants with data from Statistics Sweden.
2.3 | Internal dropout analysis
Out of the total study population with a HPA since 1995, 81 
849 participants (18.8%) lacked data on estimated VO2max. 
Reasons for a non‐valid VO2max were medication affecting 
the heart rate (such as betablockers) or heart rate outside the 
valid range. Some participants could not perform the test 
because of pain complaints, illness or perceived inability. 
Internal participation analyses for each 2‐year time period 
between 1995 and 2017 revealed that included participants, 
compared to excluded participants, were younger (42.2 
vs 46.0 years, P < 0.001), had lower body mass (78.1 vs 
81.4 kg, P < 0.001) and had higher education (27.9% univer-
sity degree vs 22.8%, P < 0.001); however, the differences 
were generally small (Table S1).
EKBLOM‐BAK Et AL.
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EKBLOM‐BAK Et AL.
2.4 | Statistical analysis
For analyses of change in VO2max between 1995 and 2017, 
years were grouped into 2‐year periods (except the first pe-
riod where we used 3 years) for reducing variations between 
years and for increasing statistical power. Mean values of 
estimated absolute and relative VO2max per 2‐year period 
were standardized, using the direct method, to the popula-
tion 18‐74 years old in Sweden in 2015 (n = 6,842,976) by 
sex, age (18‐24 years, 25‐34 years, 35‐44 years, 45‐49 years, 
50‐54 years, 55‐64 years, 65‐74 years), and length of educa-
tion (<9 years; 10‐12 years; ≥12 years). Standardized mean 
values were calculated in order to account for yearly varia-
tions in important prognostic variables (age, education, gen-
der, and region). Standardized mean values were stratified 
by sex, age (18‐34 years, 35‐49 years, 50‐74 years), educa-
tion (<9 years, 10‐12 years, ≥12 years), and county (counties 
categorized as including the three largest cities of Sweden 
“Urban,” counties including a majority of rural municipali-
ties defined by Swedish Association of Local Authorities 
and Regions “Rural,” and all other counties “All other”). 
Linear regression models were applied to study changes in 
absolute and relative VO2max over the study period within 
the total population and across subgroups. Absolute and 
relative VO2max, respectively, were introduced as depend-
ent variable, and sex, age, educational level, region, and 
year performed as independent variables. Significant change 
was defined as P < 0.05 for the performed year variable. To 
study the interaction between subgroups in decrease of ab-
solute and relative VO2max, an interaction term (performed 
year*sub‐group) was introduced in the above regression 
analyses. Significant interaction(s) were defined as P < 0.05 
for the interaction term. As all changes and interaction analy-
ses were significant, statement of a decrease or interaction 
in the manuscript refers to a significant decrease or interac-
tion. To study the change in absolute and relative VO2max 
per year between different subgroups, the probability val-
ues were computed for the difference between the B‐coef-
ficients.17 Proportions of women and men with low relative 
VO2max (<32 mL/min/kg18) per 2‐year period were calcu-
lated and standardized, using the direct method, to the same 
population as for the mean values (above). For sensitivity 
analyses, lower cutoffs, by 1 MET steps (3.5 mL/min/kg), 
were also analyzed; <28.5, <25, and <21.5 mL. Sex‐spe-
cific odds ratios (95% CI), adjusted for age and education 
level, were obtained to study and compare the annual change 
in proportion below each cutoff. Levene’s test for equality 
of variances was used to study potential increased variance 
within subgroups between the first five and last 5 years of the 
study period. The statistical analyses were conducted using 
IBM SPSS (Statistical Package for the Social Sciences for 
Windows), version 24.0.0, 2016, SPSS Inc, Chicago, IL and 
SAS version 9.4.
TABLE 1 
Distribution of sex, age, and educational level as well as standardized mean (SD) of height (cm) and weight (kg) in the study population, 1995‐2017
Year
Women
Men
N
Sex
Age
Years of education
n
Height 
Mean (SD)
Weight 
Mean (SD)
n
Height 
Mean (SD)
Weight 
Mean (SD)
Women
Men
18‐34 y
35‐49 y
50‐74 y
≤9 y
10‐12 y
>12 y
1995‐1997
4574
52%
48%
30%
48%
22%
16%
70%
14%
2395
165.4 (0.5)
66.2 (0.7)
2179
179.9 (0.4)
82.4 (0.4)
1998‐1999
6543
45%
55%
28%
44%
28%
13%
67%
19%
2964
166.4 (0.4)
66.7 (0.6)
3579
179.6 (0.4)
82.8 (0.6)
2000‐2001
12 545
49%
51%
28%
42%
31%
12%
67%
21%
6206
166.6 (0.3)
67.5 (0.6)
6339
180.0 (0.3)
84.5 (1.2)
2002‐2003
22 629
52%
48%
29%
42%
29%
11%
69%
20%
11 858
166.7 (0.5)
67.3 (0.4)
10 771
179.7 (0.2)
83.4 (0.5)
2004‐2005
37 420
52%
48%
26%
44%
31%
10%
65%
25%
19 500
166.2 (0.3)
68.4 (0.6)
17 920
179.3 (0.4)
82.6 (0.7)
2006‐2007
38 519
49%
51%
25%
44%
31%
10%
65%
25%
18 714
166.2 (0.3)
68.4 (0.4)
19 805
179.8 (0.3)
83.9 (0.6)
2008‐2009
43 479
46%
54%
26%
43%
31%
10%
65%
26%
20 068
166.2 (0.3)
68.8 (0.4)
23 411
179.7 (0.3)
84.5 (0.6)
2010‐2011
39 177
44%
56%
26%
45%
29%
9%
63%
27%
17 301
166.3 (0.2)
69.6 (0.4)
21 876
180.1 (0.3)
85.1 (0.6)
2012‐2013
57 246
41%
59%
27%
45%
28%
8%
61%
31%
23 336
166.6 (0.2)
69.5 (0.5)
33 910
180.0 (0.3)
85.0 (0.6)
2014‐2015
55 584
38%
62%
30%
43%
28%
7%
63%
30%
20 894
166.3 (0.3)
69.8 (0.5)
34 690
179.9 (0.3)
85.5 (0.6)
2016‐2017
36 561
37%
63%
33%
40%
27%
7%
64%
29%
13 464
166.1 (0.3)
69.4 (0.5)
23 097
179.9 (0.3)
85.9 (0.6)
Total
354 277
44%
56%
28%
43%
29%
9%
64%
27%
156 700
166.3 (0.3)
68.3 (0.6)
197 577
179.8 (0.3)
84.1 (0.7)
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EKBLOM‐BAK Et AL.
3 
| 
RESULTS
Participation rates by age‐group (18‐34, 35‐49 and 50‐74 years) 
were similar over time, while a variation in proportion of men 
and women as well as participants with high education from 
1995 to 2017 was more pronounced (Table 1). Standardized 
mean body mass was higher in both men (4.2%) and women 
(4.8%) in the latter compared with the early years.
Absolute VO2max decreased by 6.7% (−0.19 L/min) in the 
total population between 1995‐1997 and 2016‐2017 (Figure 
1, Table S2). Men had higher levels of absolute VO2max and 
experienced a greater decrease compared to women; −8.7% 
(−0.28 L/min) vs −5.3% (−0.13 L/min).
Relative VO2max decreased even more in the total popula-
tion (−10.8%, −4.2 mL/min/kg), in men (−12.4%, −4.8 mL) 
and women (−9.4%, −3.6 mL) (Figure 1, Table S2). The de-
crease in relative VO2max was, to one‐third, explained by a 
simultaneous increase in body mass.
Younger age‐groups had higher absolute and relative 
VO2max compared to middle‐aged and older age‐groups 
(Figure 2 A,B, Table S3). Decreases were most pronounced 
in the youngest age‐group (absolute VO2max −6.5%, rela-
tive VO2max −9.2%), compared to the middle (−3.2% and 
−7.1%) and oldest age‐group (−2.3% and −6.1%). This was 
seen for both men and women (Table S6); however, the dif-
ferences in decrease for relative VO2max were similar in all 
male age‐groups due to a larger increase in body mass in the 
middle‐aged and older age‐groups.
Participants with shorter education had lower absolute and 
relative VO2max throughout the whole study period compared 
to participants with longer education (Figure 2 C,D, Tables S4 
and S7). The decrease in absolute VO2max was greater in par-
ticipants with short (−11.4%) compared to medium (−6.2%) 
and long (−4.5%) education. A simultaneous increase in 
body mass resulted in a greater decrease in relative VO2max 
(−12.8%, −11.5%, and −7.0%, respectively). Participants with 
≥12 years of education experienced a levelling‐off in the de-
crease over the first 10 years of the 21st century. While the re-
ductions were similar across all age‐groups in participants with 
short and medium educational attainment, only the youngest 
age‐group experienced a significant decrease in VO2max in 
participants with high education (Table S8).
There was a decrease in absolute and relative VO2max in 
all county‐groups (Figure 2 E,F, Table S5). Starting off with a 
higher value in 1995‐1997, both the rural county group (absolute 
VO2max −6.5%, relative VO2max −10.5%) and all other coun-
ties (−9.4% and −14.0%) had a steeper decrease in VO2max 
compared to the group with large city‐counties (−3.5% and 
−7.8%). However, all county‐groups had similar values at the 
end of the study period. Participants with long education and 
in counties including the three largest cities had a lower yearly 
decrease in relative VO2max compared to participants in lower 
educational levels and other counties, respectively (Table 2).
The yearly decrease over the study period was 6.8 mL/min and 
0.13 mL/min/kg, respectively, with a steeper annual decrease in 
relative VO2max at the end of the 1990 s and 2010 to 2017 com-
pared to the first decade of the 21st century (Table 2). Men experi-
enced a greater decrease in relative VO2max per year compared to 
women, as well as younger age‐groups compared to older.
The proportion with low VO2max (<32 mL/min/kg) in-
creased significantly over the study period, from 27% in 
1995‐1997% to 46% in 2016‐2017, with a small but sig-
nificantly greater increase in men (26% to 46%) compared 
to women (28% to 46%), P < 0.001 (Figure 3, Table S9). 
Proportions below each lower cutoff (<28.5, 25, 21.5 mL) 
increased even further (P < 0.001) in both men and women.
Potential change in variance in relative VO2max between 
the first five (1995‐1999) and the last five (2013‐2017) years 
of the study period is presented in Table S10. The variance 
was greater in participants with long education, among mid-
dle‐aged and older at the end of the study period, while the 
variance was smaller in young women with short education.
4 
| 
DISCUSSION
In this large cohort with data spanning from 1995 to 2017, we 
found evidence of a consistent and considerable decrease in 
absolute cardiorespiratory fitness (VO2max) of −6.7% (−0.19 
L/min) in a large sample of Swedish adults. The decrease in 
FIGURE 1 
Change in standardized mean of absolute (L/min, left) and relative (mL/min/kg, right) VO2max from 1995 to 2017 in the total 
study sample and in relation to sex
EKBLOM‐BAK Et AL.
236 |   
EKBLOM‐BAK Et AL.
relative cardiorespiratory fitness was even more pronounced, 
−10.8% (−4.2 mL/min/kg), only partly explained by a si-
multaneous increase in body weight. In sub‐group analyses, 
we found that reductions were more pronounced in men, in 
young age‐groups, in those with short education, and in rural 
regions. The proportions with low cardiorespiratory fitness 
(<32 mL) increased substantially over the study period, from 
27% to 46% in the total study population, with greater, rela-
tive increases using lower cutoffs.
The present findings are similar to previous studies in 
smaller population samples and young, male military con-
scripts. Craig et al reported a lower relative VO2max in 
2007‐2009 compared to 1981 in Canadian children and 
adults.10 Repeated population‐based cross‐sectional studies 
in Swedish adults showed no change in absolute or relative 
VO2max in women between 1990, 2001 and 2013.8,9 But a 
decrease in relative VO2max in younger and middle‐aged men 
between 1990 and 2001, and in the total male group between 
1990 and 2013. The decrease in relative VO2max was mainly 
due to an increase in body mass. In male Swedish military 
conscripts, no change was seen in maximal working capac-
ity (absolute VO2max) assessed by cycle ergometer between 
1986 and 1995, however, with mean increase in body mass of 
1.9 kg over the study period.5 Moreover, relative VO2max was 
lower in Norwegian 18‐year‐old men in 2002 compared to 
1980,6 and distance achieved in a 12‐minutes running test de-
creased with almost 400 m between 1980 and 2015 in Finnish 
male conscripts.7 The decline in performance in the two latter 
cohorts was mainly explained by a simultaneous increase in 
body mass. The discrepancy between previous studies and the 
present study of change in absolute VO2max is highly inter-
esting and may partly be due to the different population stud-
ied. Though, from a public health point of view, the present 
result is alarming and may have an even greater impact on the 
health panorama, as a lower absolute aerobic work capacity 
as well as a higher body mass both have an independent asso-
ciation with increased disease risk and reduced longevity.18,19
Albeit a shift in behavioral and environmental factors 
potentially decreasing the levels of vigorous PA in the gen-
eral population, secular trend analyses of leisure‐time PA, 
including sports participation, show increasing levels during 
the past 30 years in the adult population in high‐income 
countries.8,20,21 The proportion of Swedish adults reporting 
high‐intensity exercise ≥two times/wk has increased, in all 
age‐groups and in all levels of education, between the late 
1980 s and 2006‐2007.22 This level of exertion should be suf-
ficient for at least maintaining level of VO2max in these sub-
jects. However, whether self‐reported higher levels of intense 
activity reflect an actual increase in high‐intensity exercise 
can be questioned. Although an increased participation rate 
between 1993 and 2007 in the world’s largest cross‐country 
race held annually in Sweden, increased run times were seen 
in both top, mean, and bottom quartiles, as well as in the top 
and bottom 5%, irrespectively of sex and age.23 However, 
during the same time period, work‐related PA has de-
creased significantly, with a shift from occupations requiring 
FIGURE 2 
Change in standardized mean of absolute (L/min, left) and relative (mL/min/kg, right) VO2max from 1995 to 2017 in relation to 
age‐group (A and B), length of education (C and D), and region (E and F)
EKBLOM‐BAK Et AL.
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237
EKBLOM‐BAK Et AL.
moderate‐to‐vigorous PA to predominantly sedentary or 
light PA occupations.20,21,24 As sufficient amount of physical 
stress of the cardiorespiratory system is required to maintain 
or increase VO2max, it could be hypothesized that the lower 
work‐related levels of more intense PA may partly explain 
the decrease of VO2max in the studied population of Swedish 
employees and may be a target area for future interventions.
One sub‐group that exhibited no or low decrease in both 
absolute and relative VO2max was middle‐aged and older 
participants with long education, especially during the first 
10 years of the 21st century. Looking at potential time trends 
of participation in events requiring more strenuous physi-
cal activity, there was an explosion in numbers of marathon 
finishers in Europe around the turn of the millennium, with 
approximately 200 000 finishers in year 2000 to 600 000 in 
2011.25 Running is an easy accessible form of exercise, how-
ever, also with a strong gradient in relation to educational 
level; those with highest education engages to a greater extent 
to endurance and strenuous exercise than those with lower 
education.25 Trend data from Statistics Sweden also reveal 
an accelerating proportion of the population that around 
the turn of the millennium reports high‐intensity exercise at 
least two times a week, with a more pronounced increase in 
middle‐aged and older adults but similar across educational 
levels.22 Although highly speculative, the increased interest 
and participation rates in strenuous forms of activity in some 
subgroups of the population may have had an impact on the 
lower decline of VO2max in these sub‐populations. However, 
the increased intra‐individual variance between the early and 
the latter years of the study period in the same subgroups may 
also indicate that a possible increase in participation in more 
strenuous activity may be limited to a part of, rather than the 
full, population of the sub‐group.
The mean decrease in VO2max of 4.2 mL/min/kg, with 
even larger decreases in some subgroups, is highly clinically 
relevant. A 1 MET (3.5 mL/min/kg) increase in VO2max 
has been associated with 13% and 15% decreased risk of all‐
cause mortality and CVD events, respectively.26 Moreover, a 
1 MET improvement in fitness between baseline and a second 
examination was associated with a 7%, 22%, and 12% lower 
risk of subsequent incidence of hypertension, metabolic syn-
drome, and hypercholesterolemia, respectively, after 6‐year 
follow‐up in healthy adults.19
Moreover, the considerable increase in proportion of both 
women and men with low fitness level is notable. Low fitness 
level has previously been linked to a substantially higher risk 
of all‐cause mortality after 8‐year follow‐up.27 The popula-
tion‐attributable risks assessed in the same study revealed that 
9% and 15% of all deaths in men and women, respectively, 
with low VO2max in the studied population might have been 
prevented if they had become more fit. Halting the gradual 
reduction in cardiorespiratory fitness is a clear public health 
priority for a sustainable future and of high clinical relevance, 
mainly by providing improved opportunities for regular phys-
ical activity. The greater decline in specific subgroups, with 
increasing gaps between subgroups, is especially alarming 
and may be primary targets for interventions to improve 
health in this population. For example, the steeper decrease 
in participants with short education is alarming. Lower ed-
ucational level or socioeconomic status compared to higher 
has previously been associated with lower VO2max and/or 
fulfillment of recommended levels of moderate‐to‐vigorous 
PA.28,29 This is suggested as one important contributing fac-
tor to the social inequality in health between socioeconomic 
groups, with low socioeconomic status associated with higher 
burden of disease and shorter life expectancy.11
The main strength of the present study is the large sample 
with yearly assessments of VO2max in the Swedish working 
population over a 23‐year period, with the potential to per-
form highly clinically relevant analyses of variations across 
subgroups. Previous elucidation of change in cardiorespira-
tory fitness over several decades in a large population‐based 
sample is, to our knowledge, non‐existing. Standardization 
of data in relation to the Swedish population with regard to 
sex, age, and length of education enabled comparison over 
the study period. A limitation was relatively lower number 
of participants during the early years compared to the latter, 
TABLE 2 
Changes in cardiorespiratory fitness per year in the 
total population and across subgroups
Absolute VO2max 
(ml·min−1)
Relative VO2max 
(ml·min−1·kg−1)
B (95% CI)
B (95% CI)
Total
−6.8 (−7.2 to −6.4)
−0.13 (−0.14 to −0.13)
Women
−2.4 (−3.0 to −1.9)a
−0.09 (−0.09 to −0.08)a
Men
−10.0 (−10.6 to −9.4)
−0.17 (−0.18 to −0.17)
Ageb
18–34 y
−14.2 (−15.1 to −13.3)
−0.24 (−0.25 to −0.22)
35–49 y
−5.4 (−6.0 to −4.8)
−0.12 (−0.13 to −0.11)
50–74 y
−0.4 (−1.1 to 0.3)
−0.06 (−0.07 to −0.05)
Length of education
≤9 y
−8.7 (−10.0 to −7.5)
−0.14 (−0.16 to −0.12)
10–12 y
−7.5 (−8.0 to −7.0)
−0.15 (−0.16 to −0.15)
≥12 y
−3.8 (−4.7 to −2.9)c
−0.08 (−0.09 to −0.07)c
Region (counties)
Urban
−5.8 (−6.5 to −5.1)d
−0.11 (−0.12 to −0.10)d
Rural
−7.5 (−8.4 to −6.6)
−0.16 (−0.17 to −0.14)
All other
−7.9 (−8.6 to −7.2)
−0.16 (−0.17 to −0.15)
Values are adjusted for sex, age, education level and weight (only relative 
VO2max values).
aSignificantly different women vs. men. 
bSignificantly different between all age‐groups. 
cSignificantly different from ≤9 years and 10–12 years. 
dSignificantly different from rural and all other counties. 
EKBLOM‐BAK Et AL.
238 |   
EKBLOM‐BAK Et AL.
inducing a lower power. Another limitation is the use of a 
submaximal test to estimate VO2max. However, measuring 
actual VO2max during maximal performance would not 
have been feasible in this large non‐athletic population, to-
gether with HPA test leaders not experts in work physiology 
nor with access to laboratory equipment. In addition, as-
sessment of VO2max by the Astrand protocol is reported to 
yield a valid and reliable estimation of actual VO2max.8,16 
Participants on medication that could affect heart rate re-
sponse during the submaximal test were not excluded in the 
present study. In the total study population, 79% of the par-
ticipants reported no medication, 3% reported medication, 
and 18% lacked data on medication use. The relative pro-
portion of participants reporting medication or with miss-
ing data (with the possibility that they were on medication) 
increased over the years from 1995 to 2017. However, most 
cardio‐protective treatments, including anti‐hypertensive 
medication, have typically heart rate‐lowering effects, which 
in turn would yield a higher estimated VO2max during the 
submaximal cycle test. So, if anything, the decline in esti-
mated VO2max over the years could be somewhat underes-
timated. We had only data on county of residence and not 
on municipality of residence. This might have yielded a too 
rough classification of the population when analyzing po-
tential region differences.
5 
| 
PERSPECTIVE
The present study provides for the first time evidence of an over-
all deterioration in cardiorespiratory fitness in a large cohort of 
men and women over the last three decades, which may have 
had a negative impact on performance and health in this popula-
tion. Previous studies of secular trends in VO2max have been 
limited to military conscripts or smaller samples of the general 
population. The main driver for the decline was a deterioration 
in cardiorespiratory aerobic capacity, and only partly by a si-
multaneous increase in body mass. The reduction was particu-
larly pronounced in men, in younger ages, in participants with 
a low educational level, and in rural regions. Given the strong 
associations between cardiorespiratory fitness and multiple mor-
bidities and mortality, preventing further decreases is a clear pub-
lic health priority, especially for vulnerable groups. Replication 
of findings in other countries and populations are needed.
ACKNOWLEDGEMENTS
The authors gratefully acknowledge the HPI Health Profile 
Coaches from all over Sweden. A special thanks to the mem-
bers of staff at HPI Health Profile Institute.
CONFLICT OF INTEREST
GA (responsible for research and method) and PW (CEO and 
responsible for research and method) are employed at HPI 
Health Profile Institute. JS reports personal fees from HPI 
Health Profile Institute during the conduct of the study.
ORCID
Elin Ekblom‐Bak 
 http://orcid.org/0000-0002-3901-7833 
Örjan Ekblom 
 http://orcid.org/0000-0001-6058-4982 
Erik Hemmingsson 
 http://orcid.org/0000-0001-7335-3796 
Björn Ekblom 
 http://orcid.org/0000-0002-4030-5437 
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SUPPORTING INFORMATION
Additional supporting information may be found online in 
the Supporting Information section at the end of the article.          
How to cite this article: Ekblom‐Bak E, Ekblom Ö, 
Andersson G, et al. Decline in cardiorespiratory fitness 
in the Swedish working force between 1995 and 2017. 
Scand J Med Sci Sports. 2019;29:232–239. https://doi.
org/10.1111/sms.13328

Decline in cardiorespiratory fitness in the Swedish working force between 1995 and 2017.
Ekblom-Bak, Elin,Ekblom, Örjan,Andersson, Gunnar,Wallin, Peter,Söderling, Jonas,Hemmingsson, Erik,Ekblom, Björn