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Physical activity is widely considered a magic bullet for the prevention of several non-communicable (eg, cardiovascular) diseases. Regular engagement in physical activity has been advocated in various guidelines such as those developed by the British Cardiovascular Society.1 Moreover, integration of physical activity recommendations in clinical practice, for example, among cardiologists, has often been argued for primary and secondary disease prevention.2 Although the merits of these initiatives appear to be apparent for many, new and emerging evidence suggests that the more the merrier or one size fits all approaches may not benefit everybody.
In their Heart manuscript, Ferrario and colleagues3 have reported on a sample of 3574 North Italian male workers from three different cohorts. From these workers, occupational and sport-related physical activity were assessed by questionnaires, and the incidence of cardiovascular disease (CVD) and coronary heart disease (CHD) was registered during a subsequent 14-year (median) follow-up period. Associations of occupational and sport-related physical activity with CVD and CHD were modelled, taking into account relevant factors including age, education level, different domains of physical activity, body mass index, blood cholesterol, blood pressure, smoking and alcohol use and diabetes. The authors showed that, according to expectation although not statistically significant, the risk of both CHD and CVD tended to be reduced among those reaching recommended levels of sports-related physical activity (HR (95% CI): 0.72 (0.39 to 1.32)). At the same time, however, the risk of these diseases had a tendency to be increased among those being exposed to a high level of occupational physical activity (HR (95% CI): 1.20 (0.76 to 2.08)). More interestingly, in people who were physically active at work, being active in sports according to recommendations turned out to put these workers at risk of CVD (HR (95% CI): 1.66 (0.87 to 3.14)).
The authors of this study conclude that this evidence ‘may be a further explanation of the paradoxical adverse effect of occupational physical activity on CVD risk’. With this conclusion, this article is the most recent one in a series describing different cardiovascular health outcomes for those engaging in high levels of occupational compared with leisure time physical activity, for all cause and cardiovascular mortality4 5 and CVDs, such as CHD.6 7 Moreover, this body of evidence also shows negative effects of occupational physical activity to be more pronounced among particular groups, such as those having low cardiorespiratory fitness or with pre-existing CVD.
The different cardiovascular health implications of occupational and leisure time physical activity may appear paradoxical. However, as outlined in a recent overview of potential mechanisms based on developing evidence,8 this phenomenon can be explained. In this overview, it was suggested that in contrast to leisure time physical activity, occupational physical activity is too low in intensity or too long in duration for maintaining or improving cardiorespiratory fitness and cardiovascular health, while it chronically elevates heart rate and blood pressure. Furthermore, it is often performed without sufficient recovery time and with low control over work demands. All of these factors may increase arterial wall shear stress and inflammation underlying CVD.8
Another line of thinking may be that there are methodological issues underlying the shown cardiovascular health differences between occupational and leisure time physical activity. First, above-mentioned evidence is based on self-reports of physical activity. Future research using objective (eg, accelerometer based) measurements of physical activity are needed to verify current findings. Second, high-level occupational physical activity is typically prevalent among blue collar workers from lower socioeconomic position jobs.9 Compared with high socioeconomic position groups, those with a lower socioeconomic position are known to live shorter and in poorer health, partly due to a range of lifestyle factors (eg, smoking, alcohol use and diet). Although physical activity may be one pathway for inferior cardiovascular health among people from low socioeconomic position, socioeconomic position may also exert its effects through pathways of these other lifestyle factors. Coming studies should address these pathways in more detail in order to get a better understanding of aetiological cardiovascular mechanisms for health differences associated with occupational and leisure time physical activity.
The different cardiovascular health implications of occupational and leisure time physical activity have important implications for clinical practice. This evidence suggests that in the important clinical message for patients to remain physically active, a clear distinction between leisure time and occupational physical activity should be made. Or as put by Ferrario and colleagues: ‘if our results were confirmed in larger studies, the CVD prevention recommendation of sport physical activity ought to consider the level of occupational physical activity’.3
Moreover, current research suggests that there may be groups of particular interest (eg, with lower fitness and or existing diseases) that are expected to benefit from more tailored physical activity guidance in primary and secondary (cardiovascular) disease prevention. Also, people from lower socioeconomic position appear to be a particular group of interest. This population in general spends most of its physical activity time at work while being relatively inactive during leisure time.9 Current evidence suggests that certain physical activity behaviours may not enhance cardiovascular health, as a result of which tailored physical activity recommendations as well as specific messages to reach this group are warranted.
The benefits of being physical active are apparent and undeniable in primary and secondary (cardiovascular) disease prevention. However, it appears important that clinicians (including cardiologists) and other healthcare practitioners (eg, general practitioners, occupational physicians and physical therapists) distinguish leisure time from occupational physical activity. Moreover, among these practitioners, a particular focus on vulnerable groups (with lower fitness and underlying diseases and from lower socioeconomic position) is needed. An important implication is that practitioners should be aware of the occupational demands of their patients and incorporate this in their messages towards preventing disease by integrating physical activity in clinical practice.
I would like to thank Dr Cécile Boot for being such joyful lunch company and Dr Gerben Hulsegge for making me ‘borrow’ his coffee cups. I would also like to thank these researchers for reviewing this manuscript for important intellectual content.
Contributors PC is the sole author of this paper and is responsible for its intellectual content.
Competing interests None declared.
Provenance and peer review Commissioned; externally peer reviewed.