Recent studies show how occupational and leisure-time physical activity impact health differently.
Exercise and physical activity (PA) have long been celebrated as cornerstones of a healthy lifestyle, offering protection against cardiovascular diseases, obesity, cancer, and even age-related dementia. Existing research consistently highlights the positive correlation between PA and health benefits, emphasising that more frequent and intense activity is generally better. National guidelines advocate for at least 60 minutes of moderate-to-vigorous PA daily, prompting recommendations to increase step counts and adopt standing desks to combat sedentary-related health risks.
However, recent studies have found that not all forms of exercise yield equal benefits. Specifically, recent studies suggest that occupational PA might have unexpected consequences for cognitive function. In this article, we delve into the research, exploring why occupational PA could potentially impact our brains differently.
New Study Reveals Occupational Physical Activity May be Detrimental to Cognition
Occupational PA is considered PA that fulfils the national daily requirements. However, for many people, physical work that increases heart rate and moderate-to-vigorous PA is a work requirement over which they have little control. Emerging evidence suggests that these workers not only do not reap the benefits associated with leisure-time PA but also actually experience an increased risk for the very conditions that PA is intended to prevent.
One recent study in The Lancet Regional Health – Europe investigates the relationship between occupational PA at ages 33-65 and the risk of dementia and mild cognitive impairment in later life at ages 70+. It includes 7005 participants from the HUNT4 70+ Study in Norway. In the study, they have adjusted for age and sex, education, income, marital status, cardiovascular disease, psychiatric or somatic impairment, hypertension, obesity, and insufficient leisure-time PA. These are the key findings:
- Four trajectories of occupational PA were identified: stable low, increasing then decreasing, stable intermediate, and stable high.
- Participants with stable high occupational PA had a higher risk of dementia (15.4%) and mild cognitive impairment (40.2%) compared to those with stable low PA (8.8% for dementia and 27.4% for mild cognitive impairment).
- The adjusted model showed that participants with stable high PA had a 34% higher risk of dementia and an 80% higher risk of mild cognitive impairment compared to those with stable low PA.
The study suggests that consistently high levels of occupational PA may increase the risk of cognitive impairment. The research also highlights the importance of developing strategies to prevent cognitive impairment in individuals with physically demanding jobs. The study emphasises the need for further research on the effects of occupational and leisure-time PA on cognitive health, considering the potential cardiovascular stress associated with high occupational PA.
Other Supporting Studies
These results are not the only study to show the link between occupational PA and risk of dementia. The findings support those of another longitudinal study from the Copenhagen Male Study published in 2020 where researchers also investigated the impact of occupational PA and leisure-time PA on dementia risk. The study included 4,721 male employees aged 40-59 years at baseline (in 1970-71). Adjustments were made for age, socioeconomic status, marital status, psychological stress, health behaviours, and blood pressure. They found that:
- Participants with high occupational PA had a significantly increased incidence rate ratio (IRR) of dementia (IRR = 1.48, 95% CI: 1.05-2.10) compared to those in sedentary jobs.
- On the contrary, participants with high leisure-time PA showed a non-significantly lower IRR of dementia compared to those with sedentary leisure time.
Other past studies include Hasselgren et al. and Smyth et al., who also found a significant correlation between occupational PA and dementia.
Why the “Physical Activity Paradox”?
The contrasting impacts of leisure-time PA versus occupational PA give rise to the intriguing “physical activity paradox” hypothesis. While the precise mechanisms underlying the association between occupational PA and increased dementia risk remain unclear, research has shown that higher demands in occupational PA have been correlated with smaller hippocampal volume and impaired memory performance. Further, individuals working in high-demand jobs with limited job control, where physical stress is unavoidable, tend to experience poorer cognitive performance later in life. Prolonged work hours, repetitive tasks, limited control, and stress may negatively impact cognitive development over time. In contrast, leisure-time physical activities are typically shorter, involve socialisation, play, and positive emotions, and allow flexibility to switch to other activities. Additionally, individuals can take breaks from leisure-time PA when they feel tired, while occupational PA lacks the same autonomy for recovery. As a result, people may miss out on the necessary rest to fully experience the benefits of PA. Furthermore, psychological stress at work amplifies risk.
Further Research Is Vital
However, studies like these have some limitations. The recent studies examining the effects of occupational PA often rely on older data. However, the landscape of labour markets and job demands has evolved significantly over time. With new types of tasks and skills required today, we face a dynamic work environment unlike that of 20 or 40 years ago. Additionally, the widespread adoption of remote work introduces novel factors- such as altered daily routines, disrupted sleep patterns, and potential cognitive effects- that warrant deeper investigation. To gain clarity, we must delve into the consequences of these shifts.
Guidance for Healthcare Professionals: Monitoring Patients in High Occupational Physical Activity
As healthcare professionals, it is essential to recognise the nuanced impact of occupational PA on cognitive health. While current recommendations include occupational PA, recent research underscores the need for differentiation. Here are some key considerations:
- Individual Assessment: Recognise that occupational OPA differs from leisure-time activity. Tailor advice accordingly.
- Health Equity Awareness: Be mindful of health disparities. Lower-income workers, often exposed to intense occupational PA, may not experience the expected cognitive advantages. Addressing this equity issue involves tailoring advice based on individual circumstances.
- Holistic Approach: Encourage patients to balance occupational demands with rest and recovery. Highlight the importance of adequate sleep, stress management, and breaks during work hours.
In conclusion, occupational PA and leisure-time PA have differential associations with dementia risk. While leisure-time PA is known to reduce the risk, more research is needed to understand the impact of occupational PA on cognitive health. Healthcare professionals play a crucial role in promoting cognitive health and must consider these nuances when advising patients. By considering the distinct effects of occupational PA and staying informed about evolving research, they can better support patients’ well-being.
References
- Zotcheva, E., Bratsberg, B., Strand, B. H., et al. (2023). Trajectories of occupational physical activity and risk of later-life mild cognitive impairment and dementia: the HUNT4 70+ study. The Lancet Regional Health – Europe, 34(100721). https://doi.org/10.1016/j.lanepe.2023.100721
- Nabe-Nielsen, K., Holtermann, A., Gyntelberg, F., et al. (2021). The effect of occupational physical activity on dementia: Results from the Copenhagen Male Study. Scandinavian Journal of Medicine & Science in Sports, 31(446-455). https://doi.org/10.1111/sms.13846
- Hasselgren, C., Dellve, L., Ekbrand, H., et al. (2018). Socioeconomic status, gender, and dementia: The influence of work environment exposures and their interactions with APOE epsilon4. SSM – Population Health, 5, 171-179. https://doi.org/10.1016/j.ssmph.2018.06.009
- Smyth, K. A., Fritsch, T., Cook, T. B., et al. (2004). Worker functions and traits associated with occupations and the development of AD. Neurology, 63(3), 498-503. https://doi.org/10.1212/01.WNL.0000133007.87028.09
