Christina Bjørk Petersen

Time trends in physical activity in leisure time in the Danish population from 1987 to 2005

Aims: To examine time trends in leisure-time physical activity in the Danish population from 1987 to 2005. Methods: Analyses were based on four national representative population surveys of 4752 respondents in 1987, 4667 in 1994, 16,688 in 2000, and 14,566 in 2005. Associations between leisure-time physical activity (dichotomised into high versus low) and temporal changes according to year of birth, age, and calendar-year were estimated in an age-period-cohort logistic regression model. Time trends in socioeconomic differences in physical activity were analysed by testing interaction terms. Results: The odds ratio (OR) of being highly physically active in leisure time in 2005 compared to 1987 was 1.6 (95% CI: 1.3—1.9) among men and 1.8 (95% CI: 1.5—2.2) among women. The age- and calendar-year-adjusted probability of being highly physically active increased with year of birth. The OR of being highly physically active among men and women with 13 or more years of education were 2.1 (95% CI: 1.8—2.3) and 2.0 (95% CI: 1.7—2.2), respectively, compared to individuals with less than 10 years of education. There was no significant interaction between educational level and year of interview (p>0.05). Conclusions: During the past 20 years, physical activity in leisure time has increased. Younger generations seem to be more physically active in leisure time than older generations. Due to the stable socioeconomic inequality gap in physical activity, future intervention strategies should target these inequalities.

A population-based randomized controlled trial of the effect of combining a pedometer with an intervention toolkit on physical activity among individuals with low levels of physical activity or fitness.

OBJECTIVES To examine if receiving a pedometer along with an intervention toolkit is associated with increased physical activity, aerobic fitness and better self-rated health among individuals with low levels of physical activity or fitness. METHODS The intervention was nested in the Danish Health Examination Survey (DANHES) and carried out in 2008. Participants were randomly assigned to either a pedometer group (n=326) or a control group (n=329). Physical activity, aerobic fitness, and self-rated health were measured at baseline and at 3-month follow-up, and differences were tested by Wilcoxons signed rank tests and Chi-squared tests. RESULTS At follow-up, no significant differences in physical activity, aerobic fitness and self-rated health were found between the groups. However, the oldest participants in the pedometer group reported significantly more walking time compared to the controls (controls=368 min/week, pedometer group=680 min/week, P=0.05). Among participants who completed the intervention, a significant effect on total walking time was observed (median difference=225 min/week, P=0.04). CONCLUSIONS The results suggest that receiving a pedometer and along with an intervention toolkit can increase walking time in older individuals, but not in younger individuals. Thus, this type of intervention offers great potential for promoting physical activity in older individuals. TRIAL REGISTRATION NUMBER NCT01071811.

Joint association of physical activity in leisure and total sitting time with metabolic syndrome amongst 15,235 Danish adults: A cross-sectional study

BACKGROUND Recent studies suggest that physical inactivity as well as sitting time are associated with metabolic syndrome. Our aim was to examine joint associations of leisure time physical activity and total daily sitting time with metabolic syndrome. METHODS Leisure time physical activity and total daily sitting time were assessed by self-report in 15,235 men and women in the Danish Health Examination Survey 2007-2008. Associations between leisure time physical activity, total sitting time and metabolic syndrome were investigated in logistic regression analysis. RESULTS Adjusted odds ratios (OR) for metabolic syndrome were 2.14 (95% CI: 1.88-2.43) amongst participants who were inactive in leisure time compared to the most active, and 1.42 (95% CI: 1.26-1.61) amongst those who sat for ≥10h/day compared to <6h/day. Within strata of leisure time physical activity, sitting time was positively associated with metabolic syndrome. For example, in the moderate to vigorous physical activity stratum, ORs were 1.31 (95% CI: 1.11-1.54) and 1.48 (95% CI: 1.16-1.88) in participants who sat 6-10 and ≥10h/day compared to <6h/day. CONCLUSION Higher amounts of sitting time seem to be associated with a higher prevalence of metabolic syndrome, even amongst individuals who are physically active.

Occupational heavy lifting and risk of ischemic heart disease and all-cause mortality

BackgroundOccupational heavy lifting is known to impose a high cardiovascular strain, but the risk of ischemic heart disease (IHD) from occupational heavy lifting is unknown. The objective was to investigate the association between occupational heavy lifting and risk of IHD and all-cause mortality, and the influence of occupational and leisure time physical activity on this association.MethodsData were analyzed from 1987, 1994, and 2000 from the Danish National Health Interview Surveys providing a sample of 6,692 working men and 5,921 working women aged 16–85 years without cardiovascular disease at baseline. Conventional risk factors for the outcomes IHD and all-cause mortality were controlled for in Cox analyses.ResultsAmong men, heavy lifting was associated with increased risk for IHD (hazard ratio (HR): 1.52, 95% Confidence interval (95% CI): 1.15, 2.02), while a decreased risk was associated with occupational (HR: 0.50, 95% CI: 0.37, 0.68) and leisure time (HR: 0.73, 95% CI: 0.56, 0.95) physical activity. Referencing men with high occupational physical activity and no heavy lifting, men with high occupational physical activity and heavy lifting did not have an increased risk (HR: 1.11, 95% CI:0.68, 1.82), while men with low occupational physical activity and heavy lifting had a substantial increased risk (HR: 2.56, 95% CI:1.52, 4.32). No significant associations were found for all-cause mortality or for females.ConclusionThese findings indicate an excessive risk for IHD from occupational heavy lifting among men, particularly among those with low occupational and leisure time physical activity.

Total sitting time and the risk of incident diabetes in Danish adults (the DANHES cohort) over 5 years: a prospective study

Aims To test the hypothesis that total sitting time is associated with incident diabetes, after adjustment for physical activity and obesity. Methods 72 608 Danish adults from the DANHES cohort reported their total sitting time in 2007–2008 and were followed-up for 5 years, in relation to register-based incident diabetes mellitus. Cox regression analyses were used, and the effect-modifying influence of obesity and physical activity assessed. Results The age-sex adjusted HR for developing diabetes among those who sat 10+ h/day as compared to <6 h/day was 1.35 (95% CI 1.17 to 1.57). The relative risks were similar by gender, but were largely attenuated by adjustment for potential confounding factors including physical activity, and statistically non-significant for all categories of body mass index except the obese. Conclusions The association between total sitting time and incident diabetes is substantially moderated by physical activity and obesity. Total sitting time remains a risk factor for diabetes only in inactive and obese populations.

Why do people exercise? A cross-sectional study of motives to exercise among Danish adults

There is compelling evidence that physical activity reduces the risk of cardiovascular diseases, diabetes, colon and breast cancer, obesity and musculoskeletal disorders. Furthermore, physical activity may have a beneficial effect on psychosocial well-being and mental health. Studying motives to exercise will give a better understanding of how to engage people in physical activity. Performance related factors such as strength, endurance and competition have been suggested to be more common among men, whereas women more often are motivated by losing weight and improving appearance. Health is an important motive for participation in physical activity and exercise but it may be more important to older individuals than for younger individuals. Thus age seems to influence peoples’ motives to exercise. One study suggested that individuals with a short education were less motivated by getting fit than individuals with long educations. To our

Does High Tobacco Consumption Cause Psychological Distress? A Mendelian Randomization Study

Background: Increasing evidence suggests that smoking influences mental health negatively. This study investigated whether high tobacco consumption is causally related to psychological distress in a Mendelian randomization design, using a variant in the nicotine acetylcholine receptor gene CHRNA3—known to influence individual tobacco consumption—as instrumental variable for tobacco consumption. Methods: Data from 90 108 participants in the Copenhagen General Population Study was used. Exposures included self-reported cigarettes/day and pack years and the CHRNA3 rs1051730 genotype as instrumental variable for tobacco consumption. Three dimensions of psychological distress were studied: Stress, fatigue, and hopelessness. Analyses with the CHRNA3 genotype were stratified by smoking status. Results: Self-reported amount of smoking was associated with all three dimensions of psychological distress. For instance among participants smoking 30 cigarettes/day or more, the odds ratio (OR) for stress was 1.67 (95% confidence interval [CI] 1.47–1.89) compared to never-smokers. Corresponding ORs for fatigue and hopelessness were 2.18 (95% CI 1.92–2.47) and 3.08 (95% CI 2.62–3.62). Among current smokers, homozygotes and heterozygotes for the CHRNA3 genotype had higher tobacco consumption than noncarriers. Nevertheless, the CHRNA3 genotype was not associated with psychological distress neither in current nor in former or never-smokers. For instance among current smokers, the OR for stress was 1.02 (95% CI 0.91–1.15) among homozygotes compared to noncarriers of the CHRNA3 genotype. Conclusions: Though a strong association between tobacco consumption and psychological distress was found, there was no clear evidence that high tobacco consumption was causally related to psychological distress. Implications: Smoking is associated with several mental health outcomes and smoking cessation is associated with improved mental health. Causality in the association between smoking and mental health is difficult to establish using observational data. Using a genotype known to influence tobacco consumption as instrumental variable for amount of smoking, we found no clear evidence of a direct causal path between high tobacco consumption and psychological distress. Whatever causes the strong association between tobacco consumption and psychological distress, the co-occurrence is important to consider both in interventions for smoking prevention and cessation.

Suicidal behaviour among alcohol-dependent Danes attending outpatient treatment

The association between alcohol dependence and suicidal behaviour is well established and patients with suicidal behaviour in treatment for alcohol dependence present a considerable challenge for clinical services. The aim of this study is to identify risk factors for suicide attempts and to evaluate the outcome of treatment in patients in treatment for alcohol dependence. Semi-structured, detailed interviews were administered at baseline and at three sequential follow-up interviews with a large sample of 1692 patients at an outpatient treatment centre in the county of Funen in Denmark. Characteristics of, predictors for and outcome among suicidal patients were studied. Alcohol-dependent patients with a history of suicide attempts were found to constitute a highly selected group in alcohol abuse treatment as they often had a more severe course of alcohol dependence, were unemployed, younger, were more often lowly educated, and had more physical and psychiatric problems. Traumatic childhood experience related to physical or sexual abuse was found as a major predictor for suicidal behaviour among alcohol-dependent patients. We found no significant difference in the effect of treatment in patients with and without suicidal behaviour. These results support the hypothesis that alcohol-dependent patients with a history of suicide attempts are a selected group in respect to a number of demographical and psychosocial factors, but we found no difference in the outcome of treatment. This may imply that suicidal patients in treatment for alcohol abuse are treated effectively within the present treatment settings.

Total sitting time, leisure time physical activity and risk of hospitalization due to low back pain: The Danish Health Examination Survey cohort 2007–2008

Aims: This study aimed to test the hypotheses that a high total sitting time and vigorous physical activity in leisure time increase the risk of low back pain and herniated lumbar disc disease. Methods: A total of 76,438 adults answered questions regarding their total sitting time and physical activity during leisure time in the Danish Health Examination Survey 2007–2008. Information on low back pain diagnoses up to 10 September 2015 was obtained from The National Patient Register. The mean follow-up time was 7.4 years. Data were analysed using Cox regression analysis with adjustment for potential confounders. Multiple imputations were performed for missing values. Results: During the follow-up period, 1796 individuals were diagnosed with low back pain, of whom 479 were diagnosed with herniated lumbar disc disease. Total sitting time was not associated with low back pain or herniated lumbar disc disease. However, moderate or vigorous physical activity, as compared to light physical activity, was associated with increased risk of low back pain (HR = 1.16, 95% CI: 1.03–1.30 and HR = 1.45, 95% CI: 1.15–1.83). Moderate, but not vigorous physical activity was associated with increased risk of herniated lumbar disc disease. Conclusions: The results suggest that total sitting time is not associated with low back pain, but moderate and vigorous physical activity is associated with increased risk of low back pain compared with light physical activity.

Estimated impact of replacing sitting with standing at work on indicators of body composition: Cross-sectional and longitudinal findings using isotemporal substitution analysis on data from the Take a Stand! study

The purpose was to examine and compare the effects of replacing time spent sitting with standing at work on fat-free mass, fat mass and waist circumference using isotemporal substitution. Analyses were conducted on work hours on both cross-sectional and longitudinal data. The study included 223 persons from an intervention study aimed at reducing sitting time at work among office employees. Sitting, standing and anthropometry were measured objectively. Cross-sectional isotemporal substitution analyses were modelled on baseline data, while longitudinal analyses were modelled based on differences in sitting and standing time at work between baseline and 1-month follow-up in relation to differences in anthropometric measures between baseline and 3-months follow-up. Replacing one hour of sitting time with one hour of standing was associated with a 0.21 kg higher fat-free mass in the longitudinal analysis and 0.95 kg in the cross-sectional analysis. Fat mass was 0.32 kg lower in the longitudinal analysis and 0.61 kg lower in the cross-sectional analysis. Waist circumference decreased by 0.38 cm in the longitudinal analysis and 0.81 cm in the cross-sectional analysis. Both cross-sectional and longitudinal analyses showed an effect on body composition measures by replacing one hour of sitting with standing however, this effect was largest in the cross-sectional analyses. Trial registration ClinicalTrials.gov NCT01996176.