Relationship between physical activity and aerobic capacity in chronic lung disease and in different occupational groups

Numerous studies provide evidence for the promotion of physical activity to prevent chronic diseases in healthy subjects and reduce the risk of disease progression in chronically ill patients. In addition, the level of physical activity and the resulting aerobic capacity determine the ability to actively participate in the work process. Moreover, the relation of physical activity to aerobic capacity plays a central role in the reintegration of patients after phases of sick leave. Despite the increasing number of patients in need for reintegration into the work process after diseases or medical procedures, no established reference values exist to evaluate point of time and appropriate way of return to work. Therefore, determining physical performance criteria of different occupational groups appears to be important for assessing the individual work capacity and the ability to take over tasks that are potentially physically demanding. The aim of this thesis was to objectively measure physical activity and aerobic capacity in patients with chronic obstructive pulmonary disease (COPD) (part I) as well as in healthy employees (part II) and to investigate their relationship with regard to quality of life and reintegration into employment. In a cross-sectional manner, data of 87 stable patients with COPD were analysed in part I, while 303 healthy and full-time employed adults from different occupational groups were investigated in part II. In both parts, physical activity was quantified by the SenseWear Mini armband on seven consecutive days (23 hours/day). Average daily energy expenditure, physical activity level in metabolic equivalents of task (METs), number of steps and physical activity duration at different intensities were analysed. The submaximal level of aerobic capacity was measured by the 6-minute walk test in patients with COPD, while the maximal level (VO2max) was determined with the 20-meter shuttle run test in healthy employees. Independent associations of physical activity parameters with aerobic capacity and health outcomes were examined using multiple linear regression analysis. To determine physical performance criteria of different occupational groups, the ratio between workload as measured by METs and employees’ work capacity as measured by VO2max was analysed. In patients with COPD, the number of daily steps and aerobic capacity correlated significantly with each other and were independent predictors of quality of life, whereas no relationship was found with moderate-to-high intensity activity. In contrast, in healthy employees, high-to-very high intensity activity during leisure-time was associated with high aerobic capacity. Neither daily steps nor work-related activity revealed an independent association with VO2max. The ratio of physical workload to maximum work capacity was on average one third of VO2max and increased from sedentary occupations (21%) to jobs with moderate (29%) and high (44%) physical demands. Women showed an equal absolute workload as men, but had a higher relative workload due to their lower VO2max (37% vs. 26%). Multiple linear regressions revealed that physical workload correlated positively with moderate-, high- and very high-intensity activity at work, whereas it was negatively associated with flextime, daily working hours, age and VO2max. The findings of this thesis provide evidence that the relationship between physical activity and aerobic capacity is intensity- and type-specific and varies between impaired and healthy subjects. The results emphasise the need for patients with COPD to maintain physical activity as an integral part of everyday life and to remain mobile, whereas healthy employees need to engage in sufficient high-intensity physical activity in recreation for improving VO2max. This could be explained by the fact that patients with chronic lung disease adopt a sedentary lifestyle and get used to the lower level of physical activity, while healthy subjects may require higher-intensity stimuli to achieve health benefits. Since physical activity and aerobic capacity are independent predictors of quality of life in patients with COPD, measuring activity and fitness levels should be an integral part of the assessment of patients. This may help to prevent future disease exacerbations by allowing appropriate education or treatment. Regarding the reintegration of patients after phases of sick leave, the determined gender- and job-specific physical performance criteria may help to develop future guidelines for a safe return to work. If an individual’s job profile needs to be adjusted, the present results suggest considering various personal and job-related factors for evaluating physical workload, besides VO2max. This is an important finding, since up to now work recommendations were primarily based on individuals’ aerobic capacity. An optimised reintegration process might have the potential to reduce future loss of working hours and related health care costs. With the increasing availability of big data, prescriptive analytics might in future be able to disrupt the traditional healthcare system by recommending courses of actions and showing likely outcomes based on population-derived values

Association of Occupational and Leisure-Time Physical Activity with Aerobic Capacity in a Working Population

Objective data on the association of maximal aerobic capacity (VO2max) with work related physical activity are sparse. Thus, it is not clear whether occupational physical activity (OPA) contributes to an increase of VO2max. This study examined the association of VO2max with work and non-work related physical activity in a Swiss working population

Daily physical activity, functional capacity and quality of life in patients with COPD

In the therapy of chronic obstructive pulmonary disease (COPD), it is a major goal to improve health-related quality of life (HRQOL). Patients with COPD often suffer from exertional dyspnea and adopt a sedentary lifestyle, which could be associated with poorer HRQOL. The aim of this study was to investigate the independent association of objectively measured daily physical activity and functional capacity with HRQOL in patients with COPD.; In this cross-sectional study conducted at the University Hospital Basel, Switzerland, 87 stable patients (58.6% male, mean age: 67.3 ± 9.6 yrs) with COPD in GOLD grades I (n = 23), II (n = 46), III (n = 12) and IV (n = 6) were investigated. To assess HRQOL, the COPD assessment test (CAT) was completed. Patients performed spirometry and 6-min walk test. Physical activity was measured by the SenseWear Mini Armband on 7 consecutive days. By performing a multiple linear regression analysis, independent predictors of CAT score were identified.; Age (β = -0.39, p = 0.001), average daily steps (β = -0.31, p = 0.033) and 6-min walk distance (β = -0.32, p = 0.019) were found to be independent predictors of CAT score, whereas physical activity duration above 3 METs (p = 0.498) and forced expiratory volume in 1 s in% of predicted (p = 0.364) showed no significant association.; This study showed that average daily steps and functional capacity are independent determinants of HRQOL in patients with COPD. This emphasizes the importance to remain active and mobile, which is associated with better HRQOL

Differences in classification of COPD patients into risk groups A-D: a cross-sectional study

The Global Initiative for Chronic Obstructive Lung Disease proposed in 2011 a new system to classify chronic obstructive pulmonary disease (COPD) patients into risk groups A-D, which considers symptoms and future exacerbation risk to grade disease severity. The aim of this study was to investigate the agreement between COPD risk group classifications using COPD assessment test (CAT) or modified Medical Research Council (mMRC) and severity grades or past-year exacerbations. Furthermore, physical activity across risk groups was examined.; 87 patients with stable COPD were classified into risk groups A-D. CAT and mMRC were completed. Severity grades I-IV were determined using spirometry and the number of past-year exacerbations was recorded. To test the interrater agreement, Cohen's Kappa was calculated. Daily physical activity was measured by the SenseWear Mini armband.; Using CAT, 65.5% of patients were in high-symptom groups (B and D). With mMRC, only 37.9% were in B and D. Using severity grades, 20.7% of patients were in high-exacerbation risk groups (C and D). With past-year exacerbations, 9.2% were in C and D. Interrater agreement between CAT and mMRC (κ = 0.21) and between severity grades and past-year exacerbations (κ = 0.31) was fair. Daily steps were reduced in risk groups B and C + D compared to A (p < 0.01), using either classification.; When classifying COPD patients into risk groups A-D, the use of CAT or mMRC and severity grades or past-year exacerbations does not provide equal results. Daily steps decreased with increasing COPD risk groups

Relationship between domain-specific physical activity and different body composition measures in a working population

With respect to the overweight epidemic, this study aimed to investigate the association between domain-specific physical activity and body composition measures in Swiss male employees.; A total of 192 healthy male adults in full-time employment were investigated. Height, weight, and waist circumference were measured and body mass index was calculated. Relative fat mass and relative muscle mass were determined by bioelectric impedance analysis. Physical activity was assessed by the validated International Physical Activity Questionnaire.; In multiple linear regressions, leisure-time activity showed an inverse association with waist circumference and relative fat mass and a positive correlation with relative muscle mass. Work activity was positively related to waist circumference and body mass index.; This study shows that leisure-time activity may be the most effective physical activity domain for body composition. Work activity does not seem to be protective against overweight

Sleep problems and work injury types : a study of 180 patients in a Swiss emergency department

INTRODUCTION: Sleep problems present a risk for work injuries and are a major occupational health concern worldwide. Knowledge about the influence of sleep problems on work injury patterns is limited. Therefore, the aim of this study was to identify potential associations between different types of work injuries and sleep quality, sleep duration, and daytime sleepiness. METHODS: In this hospital-based study, 180 male and female patients with work injuries were recruited at the Emergency Department of the University Hospital Basel, Switzerland, from December 1st 2009 to June 30th 2011. The data on work injury characteristics, sleep problems, and potential confounders, such as demographic, health, lifestyle, occupational and environmental factors, were collected. Multivariable logistic regression analyses were performed to investigate the relationship between sleep problems and various types of work injury. RESULTS: Each dimension of sleep problems - sleep quality, sleep duration and daytime sleepiness - was a significant risk factor for at least one type of work injury. The strongest association was found for musculoskeletal injuries and falls with short sleep duration (odds ratio [OR] 5.41, 95% confidence interval [CI] 1.81-16.22). The standardised scores of the Pittsburgh sleep quality index (PSQI) and the Epworth sleepiness scale (ESS) did not discriminate between injury types. CONCLUSION: Employees with sleep problems were more likely to suffer from certain types of work injuries. This should be considered by employers monitoring work injuries and implementing prevention measures in the company's health and safety management

Factors associated with cardiorespiratory fitness in a Swiss working population

Background . Good cardiorespiratory fitness (high ) has beneficial effects on morbidity and mortality. Therefore, a tool to estimate in daily clinical practice is of great value for preventing chronic diseases in healthy adults. This study aimed at exploring the cardiometabolic profile in a representative Swiss working population. Based on these insights, a regression model was derived revealing factors associated with . Methods . Cross-sectional data of 337 healthy and full-time employed adults recruited in the Basel region, Switzerland, were collected. Anthropometric measurements to compute body mass index (BMI) and waist circumference (WC) were performed. A 20-meter shuttle run test was conducted to determine individual . Heart rate (HR) was measured at rest, during maximal exertion, and two minutes after exercise. Systolic (SBP) and diastolic blood pressure (DBP) were assessed at rest and after exercise. A multiple linear regression model was built to identify a set of nonexercise predictor variables of . Results . Complete data of 303 individuals (63% male) aged 18 to 61 years (mean 33 ± 12 years) were considered for analysis. The regression model (adjusted R 2 = 0.647, SE = 5.3) identified sex ( β = -0.699, p < 0.001), WC ( β = -0.403, p < 0.001), difference of maximal to resting HR ( β = 0.234, p < 0.001), smoking ( β = -0.171, p < 0.001), and age ( β = -0.131, p < 0.01) as the most important factors associated with , while BMI, SBP, and DBP did not contribute to the regression model. Conclusions . This study introduced a simple model to evaluate based on nonexercise parameters as part of daily clinical routine without needing a time-consuming, cost-intense, and physically demanding direct assessment of . Knowledge about may help identifying individuals at increased cardiovascular risk and may provide the basis for health counselling and tailoring preventive measures

Physical workload and work capacity across occupational groups

This study aimed to determine physical performance criteria of different occupational groups by investigating physical activity and energy expenditure in healthy Swiss employees in real-life workplaces on workdays and non-working days in relation to their aerobic capacity (VO2max). In this cross-sectional study, 337 healthy and full-time employed adults were recruited. Participants were classified (nine categories) according to the International Standard Classification of Occupations 1988 and merged into three groups with low-, moderate- and high-intensity occupational activity. Daily steps, energy expenditure, metabolic equivalents and activity at different intensities were measured using the SenseWear Mini armband on seven consecutive days (23 hours/day). VO2max was determined by the 20-meter shuttle run test. Data of 303 subjects were considered for analysis (63% male, mean age: 33 yrs, SD 12), 101 from the low-, 102 from the moderate- and 100 from the high-intensity group. At work, the high-intensity group showed higher energy expenditure, metabolic equivalents, steps and activity at all intensities than the other groups (p<0.001). There were no significant differences in physical activity between the occupational groups on non-working days. VO2max did not differ across groups when stratified for gender. The upper workload limit was 21%, 29% and 44% of VO2max in the low-, moderate- and high-intensity group, respectively. Men had a lower limit than women due to their higher VO2max (26% vs. 37%), when all groups were combined. While this study did confirm that the average workload limit is one third of VO2max, it showed that the average is misrepresenting the actual physical work demands of specific occupational groups, and that it does not account for gender-related differences in relative workload. Therefore, clinical practice needs to consider these differences with regard to a safe return to work, particularly for the high-intensity group