Reference values for estimated VO2max by two submaximal cycle tests: the Åstrand-test and the Ekblom-Bak test.

AIMS: Submaximal tests estimating VO2max have inherent biases; hence, using VO2max estimations from the same test is essential for reducing this bias. This study aimed to establish sex- and age-specific reference values for estimated VO2max using the Åstrand-test (Å-test) and the Ekblom-Bak test (EB-test). We also assessed the effects of age, exercise level, and BMI on VO2max estimations. METHODS: We included men and women (20-69 years) from the Swedish working population participating in Health Profile Assessments between 2010 and 2020. Excluding those on heart rate-affecting medicines and smokers, n = 263,374 for the Å-test and n = 95,043 for the EB-test were included. VO2max reference values were based on percentiles 10, 25, 40, 60, 75, and 90 for both sexes across 5-year age groups. RESULTS: Estimated absolute and relative VO2max were for men 3.11 L/min and 36.9 mL/min/kg using the Å-test, and 3.58 L/min and 42.4 mL/min/kg using the EB-test. For women, estimated absolute and relative VO2max were 2.48 L/min and 36.6 mL/min/kg using the Å-test, and 2.41 L/min and 35.5 mL/min/kg using the EB-test. Higher age (negative), higher exercise level (positive), and higher BMI (negative) were associated with estimated VO2max using both tests. However, explained variance by exercise on estimated VO2max was low, 10% for the Å-test and 8% for the EB-test, and moderate for BMI, 23% and 29%. CONCLUSION: We present reference values for estimated VO2max from two submaximal cycle tests. Age, exercise, and BMI influenced estimated VO2max. These references can be valuable in clinical evaluations using the same submaximal tests.

Association between change in cardiorespiratory fitness and prostate cancer incidence and mortality in 57 652 Swedish men.

OBJECTIVES: To examine the associations between changes in cardiorespiratory fitness (CRF) in adulthood and prostate cancer incidence and mortality. METHODS: In this prospective study, men who completed an occupational health profile assessment including at least two valid submaximal CRF tests, performed on a cycle ergometer, were included in the study. Data on prostate cancer incidence and mortality were derived from national registers. HRs and CIs were calculated using Cox proportional hazard regression with inverse probability treatment weights of time-varying covariates. RESULTS: During a mean follow-up time of 6.7 years (SD 4.9), 592 (1%) of the 57 652 men were diagnosed with prostate cancer, and 46 (0.08%) died with prostate cancer as the primary cause of death. An increase in absolute CRF (as % of L/min) was associated with a reduced risk of prostate cancer incidence (HR 0.98, 95% CI 0.96 to 0.99) but not mortality, in the fully adjusted model. When participants were grouped as having increased (+3%), stable (±3%) or decreased (-3%) CRF, those with increased fitness also had a reduced risk of prostate cancer incidence compared with those with decreased fitness (HR 0.65, 95% CI 0.49 to 0.86), in the fully adjusted model. CONCLUSION: In this study of employed Swedish men, change in CRF was inversely associated with risk of prostate cancer incidence, but not mortality. Change in CRF appears to be important for reducing the risk of prostate cancer.

Association Between Cardiorespiratory Fitness and Cancer Incidence and Cancer-Specific Mortality of Colon, Lung, and Prostate Cancer Among Swedish Men.

Importance: Cardiorespiratory fitness (CRF) levels appear to be an important risk factor for cancer incidence and death. Objectives: To examine CRF and prostate, colon, and lung cancer incidence and mortality in Swedish men, and to assess whether age moderated any associations between CRF and cancer. Design, Setting, and Participants: A prospective cohort study was conducted in a population of men who completed an occupational health profile assessment between October 1982 and December 2019 in Sweden. Data analysis was performed from June 22, 2022, to May 11, 2023. Exposure: Cardiorespiratory fitness was assessed as maximal oxygen consumption, estimated using a submaximal cycle ergometer test. Main Outcomes and Measures: Data on prostate, colon, and lung cancer incidence and mortality were derived from national registers. Hazard ratios (HRs) and 95% CIs were calculated using Cox proportional hazards regression. Results: Data on 177 709 men (age range, 18-75 years; mean [SD] age, 42 [11] years; mean [SD] body mass index, 26 [3.8]) were analyzed. During a mean (SD) follow-up time of 9.6 (5.5) years, a total of 499 incident cases of colon, 283 of lung, and 1918 of prostate cancer occurred, as well as 152 deaths due to colon cancer, 207 due to lung cancer, and 141 deaths due to prostate cancer. Higher levels of CRF (maximal oxygen consumption as milliliters per minute per kilogram) were associated with a significantly lower risk of colon (HR, 0.98, 95% CI, 0.96-0.98) and lung cancer (HR, 0.98; 95% CI, 0.96-0.99) incidence, and a higher risk of prostate cancer incidence (HR, 1.01; 95% CI, 1.00-1.01). Higher CRF was associated with a lower risk of death due to colon (HR, 0.98; 95% CI, 0.96-1.00), lung (HR, 0.97; 95% CI, 0.95-0.99), and prostate (HR, 0.95; 95% CI, 0.93-0.97) cancer. After stratification into 4 groups and in fully adjusted models, the associations remained for moderate (>35-45 mL/min/kg), 0.72 (0.53-0.96) and high (>45 mL/min/kg), 0.63 (0.41-0.98) levels of CRF, compared with very low (<25 mL/min/kg) CRF for colon cancer incidence. For prostate cancer mortality, associations remained for low (HR, 0.67; 95% CI, 0.45-1.00), moderate (HR, 0.57; 95% CI, 0.34-0.97), and high (HR, 0.29; 95% CI, 0.10-0.86) CRF. For lung cancer mortality, only high CRF (HR, 0.41; 95% CI, 0.17-0.99) was significant. Age modified the associations for lung (HR, 0.99; 95% CI, 0.99-0.99) and prostate (HR, 1.00; 95% CI, 1.00-1.00; P < .001) cancer incidence, and for death due to lung cancer (HR, 0.99; 95% CI, 0.99-0.99; P = .04). Conclusions and Relevance: In this cohort of Swedish men, moderate and high CRF were associated with a lower risk of colon cancer. Low, moderate, and high CRF were associated with lower risk of death due to prostate cancer, while only high CRF was associated with lower risk of death due to lung cancer. If evidence for causality is established, interventions to improve CRF in individuals with low CRF should be prioritized.

Lifestyle-related habits and factors before and after cardiovascular diagnosis: a case control study among 2,548 Swedish individuals.

BACKGROUND: Healthy lifestyle habits are recommended in prevention of cardiovascular disease (CVD). However, there is limited knowledge concerning the change in lifestyle-related factors from before to after a CVD event. Thus, this study aimed to explore if and how lifestyle habits and other lifestyle-related factors changed between two health assessments in individuals experiencing a CVD event between the assessments, and if changes varied between subgroups of sex, age, educational level, duration from CVD event to second assessment and type of CVD event. METHODS: Among 115,504 Swedish employees with data from two assessments of occupational health screenings between 1992 and 2020, a total of 637 individuals (74% men, mean age 47 ± SD 9 years) were identified having had a CVD event (ischemic heart disease, cardiac arrythmia or stroke) between the assessments. Cases were matched with controls without an event between assessments from the same database (ratio 1:3, matching with replacement) by sex, age, and time between assessment (n = 1911 controls). Lifestyle habits included smoking, active commuting, exercise, diet, alcohol intake, and were self-rated. Lifestyle-related factors included overall stress, overall health (both self-rated), physical capacity (estimated by submaximal cycling), body mass index and resting blood pressure. Differences in lifestyle habits and lifestyle-related factors between cases and controls, and changes over time, were analysed with parametric and non-parametric tests. Multiple logistic regression, OR (95% CI) was used to analyse differences in change between subgroups. RESULTS: Cases had, in general, a higher prevalence of unhealthy lifestyle habits as well as negative life-style related factors prior to the event compared to controls. Nevertheless, cases improved their lifestyle habits and lifestyle factors to a higher degree than controls, especially their amount of active commuting (p = 0.025), exercise (p = 0.009) and non-smoking (p < 0.001). However, BMI and overall health deteriorated to a greater extent (p < 0.001) among cases, while physical capacity (p < 0.001) decreased in both groups. CONCLUSION: The results indicate that a CVD event may increase motivation to improve lifestyle habits. Nonetheless, the prevalence of unhealthy lifestyle habits was still high, emphasizing the need to improve implementation of primary and secondary CVD prevention.

Mediation of lifestyle-associated variables on the association between occupation and incident cardiovascular disease.

The main aim was to examine the association between occupational groups and incident cardiovascular disease (CVD), and to which extent associations are mediated by lifestyle-associated variables (cardiorespiratory fitness, smoking, BMI, exercise, and diet). A total of 304,702 participants (mean age 42.5 yrs., 47% women), who performed a health profile assessment in Sweden between 1982 and 2019, were included in the analyses. CVD incidence was obtained from national registers. All participants were free from CVD prior to the health profile assessment. Occupational group was defined using the Swedish Standard Classification of Occupations and analyzed separately (13 different occupational groups) as well as after aggregation into four occupational groups (white-collar high-skilled, white-collar low-skilled, blue-collar high-skilled and blue-collar low-skilled). Cardiorespiratory fitness, BMI, exercise, smoking, and diet were included as mediators and analyzed separately in single models and simultaneously in one multiple mediation model. All mediation analyses were adjusted for sex, age, length of education and calendar time. White-collar high-skilled was set as reference in all analyses. Blue-collar and low-skilled occupation had a higher risk of incident CVD compared to the reference. Cardiorespiratory fitness, BMI, exercise, smoking, and diet mediated 48% to 54% of the associations between reference and the other aggregated occupational groups. In the single model, the strongest mediators were cardiorespiratory fitness, smoking and BMI. In conclusion, blue-collar and low-skilled occupations had a significantly higher risk for incident CVD compared to white-collar high-skilled workers, with the association mediated to a large extent by variation in lifestyle-associated variables.

Cardiorespiratory fitness and lifestyle on severe COVID-19 risk in 279,455 adults: a case control study.

BACKGROUND: The impact of cardiorespiratory fitness (CRF) and other lifestyle-related factors on severe COVID-19 risk is understudied. The present study aims to investigate lifestyle-related and socioeconomic factors as possible predictors of COVID-19, with special focus on CRF, and to further study whether these factors may attenuate obesity- and hypertension-related risks, as well as mediate associations between socioeconomic factors and severe COVID-19 risk. METHODS: Out of initially 407,131 participants who participated in nationwide occupational health service screening between 1992 and 2020, n = 857 cases (70% men, mean age 49.9 years) of severe COVID-19 were identified. CRF was estimated using a sub-maximum cycle test, and other lifestyle variables were self-reported. Analyses were performed including both unmatched, n = 278,598, and sex-and age-matched, n = 3426, controls. Severe COVID-19 included hospitalization, intensive care or death due to COVID-19. RESULTS: Patients with more severe COVID-19 had significantly lower CRF, higher BMI, a greater presence of comorbidities and were more often daily smokers. In matched analyses, there was a graded decrease in odds for severe COVID-19 with each ml in CRF (OR = 0.98, 95% CI 0.970 to 0.998), and a two-fold increase in odds between the lowest and highest (< 32 vs. ≥ 46 ml·min-1·kg-1) CRF group. Higher BMI (per unit increase, OR = 1.09, 1.06 to 1.12), larger waist circumference (per cm, OR = 1.04, 1.02 to 1.06), daily smoking (OR = 0.60, 0.41 to 0.89) and high overall stress (OR = 1.36, 1.001 to 1.84) also remained significantly associated with severe COVID-19 risk. Obesity- and blood pressure-related risks were attenuated by adjustment for CRF and lifestyle variables. Mediation through CRF, BMI and smoking accounted for 9% to 54% of the associations between low education, low income and blue collar/low skilled occupations and severe COVID-19 risk. The results were consistent using either matched or unmatched controls. CONCLUSIONS: Both lifestyle-related and socioeconomic factors were associated with risk of severe COVID-19. However, higher CRF attenuated the risk associated with obesity and high blood pressure, and mediated the risk associated with various socioeconomic factors. This emphasises the importance of interventions to maintain or increase CRF in the general population to strengthen the resilience to severe COVID-19, especially in high-risk individuals.

Workplace sitting is associated with self-reported general health and back/neck pain: a cross-sectional analysis in 44,978 employees.

BACKGROUND: Total sitting time is associated with a higher risk for cardio metabolic disease and mortality, while breaks in prolonged sitting attenuate these effects. However, less is known about associations of different specific domains and breaks of sitting on general health, back/neck pain and if physical activity could influence these associations. The aim was to investigate how workplace sitting and frequency of breaking up workplace sitting is associated with self-reported general health and self-reported back/neck pain. METHODS: 44,978 participants (42% women) from the Swedish working population, who participated in a nationwide occupational health service screening 2014-2019, were included in this cross-sectional study. Self-reported sitting duration and frequency of breaks from sitting at work, general health, back/neck pain, exercise, leisure time sitting, diet, smoking, stress and body mass index were assessed. Occupation was classified as requiring higher education qualifications or not. Logistic regression modelling was used to assess the association between workplace sitting/frequency of breaks in workplace sitting and poor general health and back/neck pain, respectively. RESULTS: Compared to sitting all the time at work, sitting ≤75% of the time showed significantly lower risks for poor general health (OR range 0.50-0.65), and sitting between 25 and 75% of the time showed significantly lower risks (OR 0.82-0.87) for often reported back/neck pain. For participants reporting sitting half of their working time or more, breaking up workplace sitting occasionally or more often showed significantly lower OR than seldom breaking up workplace sitting; OR ranged 0.40-0.50 for poor health and 0.74-0.81 for back/neck pain. CONCLUSIONS: Sitting almost all the time at work and not taking breaks is associated with an increased risk for self-reported poor general health and back/neck pain. People sitting almost all their time at work are recommended to take breaks from prolonged sitting, exercise regularly and decrease their leisure time sitting to reduce the risk for poor health.

Lifestyle Habits and Mental Health in Light of the Two COVID-19 Pandemic Waves in Sweden, 2020.

The COVID-19 pandemic has become a public health emergency of international concern, which may have affected lifestyle habits and mental health. Based on national health profile assessments, this study investigated perceived changes of lifestyle habits in response to the COVID-19 pandemic and associations between perceived lifestyle changes and mental health in Swedish working adults. Among 5599 individuals (50% women, 46.3 years), the majority reported no change (sitting 77%, daily physical activity 71%, exercise 69%, diet 87%, alcohol 90%, and smoking 97%) due to the pandemic. Changes were more pronounced during the first wave (April-June) compared to the second (October-December). Women, individuals <60 years, those with a university degree, white-collar workers, and those with unhealthy lifestyle habits at baseline had higher odds of changing lifestyle habits compared to their counterparts. Negative changes in lifestyle habits and more time in a mentally passive state sitting at home were associated with higher odds of mental ill-health (including health anxiety regarding one's own and relatives' health, generalized anxiety and depression symptoms, and concerns regarding employment and economy). The results emphasize the need to support healthy lifestyle habits to strengthen the resilience in vulnerable groups of individuals to future viral pandemics and prevent health inequalities in society.

Association between change in cardiorespiratory fitness and incident hypertension in Swedish adults.

AIMS: To explore how change in cardiorespiratory fitness is associated with incident hypertension in adults, and whether the association varies between sex, age, body mass index, cardiorespiratory fitness at baseline and follow-up time. A second aim is to study how change in other lifestyle-related variables affects the results. METHODS: A total of 91,728 participants (48% women), normotensive at baseline, with two examinations from occupational health service screenings between 1982 and 2019 (mean duration 4.3 years) were included. Cardiorespiratory fitness was assessed as estimated maximal oxygen consumption using submaximal cycle testing. Change in cardiorespiratory fitness was expressed as the percentage change per year. Incident hypertension was defined as systolic blood pressure of 140 mmHg or greater or diastolic blood pressure of 90 mmHg or greater, or self-reported physician-diagnosed hypertension, at second examination. RESULTS: A large increase (≥3% annual change) in cardiorespiratory fitness was associated with a 11% lower risk of incident hypertension compared with maintainers (-1 to +1%), after multi-adjustment including change in smoking, body mass index, diet, stress and exercise habits. On the contrary, a small (-1 to -<3%) and large (≥-3%) decrease in cardiorespiratory fitness associated with a 21% and 25% higher risk compared with maintainers. Longer duration between the examinations was associated with stronger risk associations. Preserving, or changing to, risk level for the other lifestyle variables was associated with a higher risk of incident hypertension. However, a simultaneous maintenance of or increase in cardiorespiratory fitness attenuated the risk associated with smoking, and stress. CONCLUSION: Preserving or increasing cardiorespiratory fitness should be part of any long-term strategy to decrease the risk of incident hypertension.

Lifestyle-associated health risk indicators across a wide range of occupational groups: a cross-sectional analysis in 72,855 workers.

BACKGROUND: Identify and compare health risk indicators for common chronic diseases between different occupational groups. METHODS: A total of 72,855 participants (41% women) participating in an occupational health service screening in 2014-2019 were included. Occupation was defined by the Swedish Standard Classification of Occupation, and divided into nine major and additionally eight sub-major groups. These were analysed separately, as white- and blue-collar occupations and as low- and high-skilled occupations. Seven health risk indicators were self-reported: exercise, physical work situation, sitting at work and leisure, smoking, diet, and perceived health, whereas cardiorespiratory fitness, BMI and blood pressure were measured. These were further dichotomized (yes/no) and as clustering of risk indicators (≥3 vs. <3). RESULTS: The greatest variation in OR across sub-major and major occupational groups were seen for daily smoking (OR = 0.68 to OR = 5.12), physically demanding work (OR = 0.55 to OR = 45.74) and high sitting at work (OR = 0.04 to OR = 1.86). For clustering of health risk indicators, blue-collar workers had significantly higher clustering of health risks (OR: 1.80; 95% CI 1.71-1.90) compared to white-collar workers (reference). Compared to high-skilled white-collar workers, low-skilled white-collar workers had similar OR (2.00; 1.88-2.13) as high-skilled blue-collar workers (1.98; 1.86-2.12), with low-skilled blue-collar workers having the highest clustered risk (2.32; 2.17-2.48). CONCLUSION: There were large differences in health risk indicators across occupational groups, mainly between high-skilled white-collar occupations and the other occupations, with important variations also between major and sub-major occupational groups. Future health interventions should target the occupational groups identified with the highest risk for effective disease prevention.

Sex- and age-specific associations between cardiorespiratory fitness, CVD morbidity and all-cause mortality in 266.109 adults.

The aim was to investigate sex- and age-specific associations between cardiorespiratory fitness, all-cause and cause-specific mortality, and cardiovascular disease (CVD) morbidity. 266.109 participants (47% women, 18-74 years) free from CVD, participating in occupational health service screenings in 1995-2015 were included. CRF was assessed as estimated maximal oxygen consumption (estVO2max) using a submaximal cycle test. Incident cases of first-time CVD event and death from any cause were ascertained through national registers. There were 4244 CVD events and 2750 cases of all-cause mortality during mean 7.6 years follow-up. Male gender, higher age and lower estVO2max were associated with higher all-cause mortality and CVD morbidity incidence rates. Risk reductions with increasing estVO2max were present in all age-groups of men and women. No obvious levelling off in risk was identified in the total cohort. However, women and older age-groups showed no further reduction in higher aggregated estVO2max levels. CVD specific mortality was more associated with estVO2max compared to tumor specific mortality. The risk for all-cause mortality and CVD morbidity decreased by 2.3% and 2.6% per increase in 1 ml·min-1·kg-1 with no significant sex-differences but more pronounced in the three lower estVO2max categories for all-cause mortality (9.1%, 3.8% and 3.3%, respectively). High compared to lower levels of estVO2max was not related to a significantly elevated mortality or morbidity. In this large cohort study, CVD morbidity and all-cause mortality were inversely related to estVO2max in both men and women of all age-groups. Increasing cardiorespiratory fitness is a clear public health priority.

Decline in cardiorespiratory fitness in the Swedish working force between 1995 and 2017.

BACKGROUND: Long-term trend analyses of cardiorespiratory fitness (VO2 max) in the general population are limited. OBJECTIVES: To describe trends in VO2 max from 1995 to 2017 in the Swedish working 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 participated 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) VO2 max, and the proportion with low (<32) relative VO2 max are reported. VO2 max was estimated using a submaximal cycle test. RESULTS: Absolute VO2 max decreased by -6.7% (-0.19 L/min) in the total population. Relative VO2 max 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 regions (6.5% vs 3.5%), all P < 0.001. The proportions with low VO2 max 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 education, and living in a rural area were predictive of greater reductions. The proportion with low cardiorespiratory fitness almost doubled. Given the strong associations between cardiorespiratory fitness and multiple morbidities and mortality, preventing further decreases is a clear public health priority, especially for vulnerable groups.