Lack of autonomy
Specific characteristics indirectly associated with high occupational PA jobs – low cognitive stimuli, lifestyle factors, and socioeconomic influences – as well as factors directly related to high occupational PA, such as long hours, repetitive tasks, low levels of control, and stress, could also adversely affect cognitive trajectories, Dr. Skirbekk explained.
“By contrast, leisure-time physical activities tend to be of much shorter duration; are associated with socialization, play, [and] positive emotions; and [include] the opportunity to take breaks or shift to other types of activities if one prefers,” he said. “It may also be that too little or too much PA could be adversely related to cognitive outcomes – hence moderate activity levels, for example 10,000 steps a day, are still likely beneficial for cognitive functioning.”
Dr. Quinn said most of the CVD risk linked to occupational PA has to do with long periods of exertion such as lifting and carrying objects. While occupational standing and walking all day are also linked to CVD risk, they’re not as risky as lifting and carrying, he said.
Like Dr. Skirbekk, Dr. Quinn noted that individuals can take a break from leisure-time PA when they are tired, but occupational PA doesn’t have that same autonomy to allow for recovery.
“So, in many cases, individuals are not getting the recovery their body needs to actually experience PA benefits, because those benefits come during rest,” Dr. Quinn said.
“We’ve shown that PA at work raises acute cardiovascular responses, which are related to cardiovascular risk. For example, 24-hour and waking heart rate and diastolic blood pressure, as well as nonwork diastolic blood pressure, all were significantly higher on workdays versus non-workdays,” he said.
Dr. Quinn also said that psychological stress at work amplifies risk. “A person who does PA at work and is stressed is likely to be at greater risk than someone who has a physically active job but doesn’t have psychological stress combined with it.”
Research gaps
However, Dr. Skirbekk noted that there are strategies that can reduce the risk for MCI and dementia despite high levels of occupational PA. “It is often difficult to change professions, and even if you do, it won’t immediately affect cognition. But altering one’s lifestyle is likely to have effects on cognitive development across the life cycle.
“Many clinicians say they always advise lifestyle changes, but nothing happens. But it makes sense to emphasize that these changes – stopping smoking, eating well, getting proper sleep, etc. – affect not only cardiovascular risk but also cognition. And I think clinicians should also take a patient’s occupation into account during any evaluation,” Dr. Skirbekk noted.
Dr. Quinn said it isn’t realistic to expect workers to come up with solutions to the PA paradox because many don’t have the autonomy to be able to mitigate their occupational risk.
“I think administrative controls and policy changes eventually will be the levers of change. We’re not quite there yet, but those are the types of things we should do when we’re trying to reduce loads in some way, or reduce the time that people spend doing certain tasks we know are potentially bad,” he said.
However, not everyone agrees that occupational PA doesn’t confer the same benefits of leisure-time PA, at least with respect to cardiovascular risk. For example, the Prospective Urban Rural Epidemiology (PURE) study, which includes a cohort of 130,000 people from 17 high-income, middle-income, and low-income countries, concluded that both higher recreational and nonrecreational PA were associated with a lower risk for mortality and CVD events.
What additional research is needed to clarify the effects of occupational and leisure-time activity and to address conflicting findings?
“Even studies coming out now regarding the effects of occupational PA have mainly used older data,” Dr. Skirbekk noted. “Labor markets and job demands have changed over time. There are different types of tasks and skills required now than there were 20 or 40 years ago. And of course, working from home is a recent phenomenon that’s happened on a large scale and might affect daily routines, sleep patterns, and also cognition. We need a better understanding of what the consequences might be.”