Time to rethink physical activity advice and blood pressure: A role for occupation-based interventions?

Cardiovascular death is the leading cause of mortality in women.1 Low physical fitness and sedentary behaviour are recognized as major risk factors2 and increased physical activity is therefore promoted as a strategy to reduce cardiovascular risk.3 Recommendations advise at least 150 minutes of moderate to vigorous activity per week and, when possible, reduced sitting time,3 with cardiovascular benefits gained from as little as 15 minutes of exercise per day.4 The same recommendations apply to patients with a history of cardiovascular disease, such as myocardial infarction or chronic heart failure,3 and systematic review evidence supports the use of aerobic exercise and resistance training in other chronic disease management settings, including blood pressure control.5–7 A major challenge for the health care community is the delivery of affordable interventions, which maintain increased physical activity behaviour in the long term, to sustain the health benefits. Environmental and lifestyle modifications across a range of domains – including transport, leisure, home and education – provide an important opportunity to increase activity within a population.8 Workplace-based physical activity interventions in particular have been identified as a way to provide effective risk reduction9 and, reassuringly, the reported incidence of serious adverse events in randomized control trials and within disease populations undergoing cardiac rehabilitation programmes is low.10 However, despite this volume of evidence that physical activity is good, it is possible that cardiovascular risk is increased in some people during certain types of exercise. Physical activity increases blood pressure, with heavy resistance exercise being associated with the most extreme transient changes in systolic levels.11 This type of static exercise reduces venous return and increases the cardiac afterload as well as strain. The presence of disease may further exacerbate these increases in blood pressure as people at risk of hypertension are known to have an exaggerated blood pressure response to exercise.12 People who exhibit this response are at increased risk of stroke13 and cardiovascular death.14 Similar transient physiological stresses to those observed in resistance exercise programmes may occur in occupational settings where people lift or manoeuvre heavy loads. Allesøe et al.15 have reported a prospective cohort study that explores the association between questionnaire-reported workplace physical activity and incident ischaemic heart disease retrieved from a national register of hospital discharges. They found that, in an occupational setting, self-reported high physical activity levels in women with hypertension were associated with a three-fold greater risk of future ischaemic heart disease than that seen in normotensive women who reported moderate physical activity at work. This is a novel finding in a population of over 12,000 women monitored prospectively for nearly 15 years. Previous occupation-based studies have tended to focus on male employees and therefore the authors should be commended for addressing this relevant question in a female population. There are distinct features of cardiovascular disease specific to women, such as the development of early hypertension related to pregnancy,16 as well as unique patterns of aortic17 and cardiac remodelling18 that may be relevant to their blood pressure response and warrant tailored primary prevention advice.19 The type of occupation may need to be part of this advice, but, equally, occupation may be important because it offers a setting and opportunity to optimize the provision for screening, management and control of hypertension in women. In the study by Allesøe et al.,15 the hypertensive women reported relatively high rates of under-treatment, with increased risk of mortality across all intensities of occupational activity compared with the normotensive population. Under-diagnosis and suboptimum management remains a consistent problem for blood pressure control, especially in younger adult populations in a range of health care settings.20 Recent systematic review evidence supports the benefits of the aggressive control of blood pressure across age groups21 and occupation-based interventions may provide a valuable environment to titrate blood pressure control and optimize primary prevention in women. The main findings of Allesøe et al.15 suggest that this advice may need to be personalized further as there may be a hypertensive subgroup of an occupational population who are at particularly increased risk from transient exertional stress. This contrasts with the general trend reported from meta-analyses of longitudinal cohort studies about the beneficial effects of exposure to moderate to high occupational physical activity.22,23 These published data are largely from European and North American cohorts and the exposure to extreme physical exertion in these populations has steadily decreased with the transition to service economies.24 To ensure that physical activity guidelines are relevant to a broader range of economies and health care settings, there may be a need to include more diverse populations and follow cohorts from heavier industries and manufacturing. Nevertheless, other challenges in studies of occupational physical activity need to be taken into consideration in the interpretation of these results. The majority of studies, including that by Allesøe et al.,15 rely on self-reporting measures of physical activity, which can lead to selective reporting and the potential of ‘image control’ on the part of the responding health care professional. The reported rates of leisure time activity suggest that >90% of the population in the study by Allesøe et al.15 were moderately to vigorously active during their leisure time. Previous studies in male populations have been able to demonstrate an interaction effect across domains of activity, with the risk of high occupational physical activity reduced by maintaining these levels of high leisure time activity.25 Future studies with more detailed questionnaires and report logs will improve the measurement of physical activity behaviours across domains and potentially control for ‘floor and ceiling’ effects.26 Ideally, multimodality measures of physical activity behaviour, including objective measures, may be required to ensure the accurate assessment of physical activity for an individual person. The potential of such future studies is that they may be able to validate and refine our characterization of the group of hypertensive women identified by Allesøe et al.15 who are most at risk from higher levels of physical activity. In addition, the use of more objective measures of activity may be of practical value in the design of physical activity interventions. The study by Allesøe et al.15 has raised relevant and interesting questions about the association between exposure to occupational physical activity and cardiovascular disease in a large population of female health care professionals. The study highlights a potential need for personalized, occupation-based health promotion and advice, which takes into account important characteristics of the participants such as a history of hypertension. Continued research into why there is heterogeneity in the cardiovascular protective response to exercise also needs to be undertaken and the occupational context of the study population may be an important factor. Improved measurement and tracking of risk exposures and associated covariants, including tools to capture the full spectrum of physical activity across all domains, will provide greater clarification of the occupation-associated risks. In the general population, the greatest challenge may be to facilitate breaks in sitting time and increases in light to moderate activity, while ensuring that those with more demanding transient exertional exposures at work are fit for the job. The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. The author(s) received no financial support for the research, authorship, and/or publication of this article.