In their public health guidelines, the World Health Organization (WHO) recommend that children and teenagers aged 5–17 should get "at least 60 minutes of moderate- to vigorous-intensity physical activity daily."
Adults aged 18–64, meanwhile, should aim for at least 150 minutes of aerobic exercise each week.
But most recommendations do not differentiate between occupational, leisure, and transportation-related physical activity. And yet, some believe that the type of exercise in which people engage may make all the difference when it comes to whether such activities are beneficial or, to the contrary, detrimental to health.
Pieter Coenen — of the Vrije Universiteit University Medical Center in Amsterdam, the Netherlands — alongside several international scholars recently set out to analyze existing evidence indicating that occupational physical activity actually increases the risk of premature death from all causes.
The researchers produced a systematic review of the studies looking at the detrimental effect that occupational physical activity has on individuals' health. Their findings are now published in the British Journal of Sports Medicine.
'A physical activity paradox'
"Until recently," the researchers note, "the health effects associated with different domains of [physical activity] were considered to be alike and beneficial."
"New evidence, however, suggests a contrast between the health effects of leisure time and occupational [physical activity], suggesting a [physical activity] paradox."
"Specifically," they explain, "while beneficial health outcomes have been associated with high level leisure time [physical activity], detrimental health consequences have been documented for high level occupational [physical activity], regarding cardiovascular disorders, sickness absence, and mortality."
Coenen and his colleagues analyzed 17 studies — ranging from 1960 to 2010 — that considered the link between work-related physical activity and all-cause mortality, amounting to a pool of data on 193,696 individuals.
Men who engaged in high levels of physical activity in the workplace had an 18 percent higher risk of premature death compared with peers with more inactive roles. Individuals at risk, the researchers note, tend to be "blue collar," or manual, workers.
Even after accounting for exercise during leisure time, the link remained in place. As the authors explain, "The results of this review indicate detrimental health consequences associated with high level occupational physical activity in men, even when adjusting for relevant factors (such as leisure time physical activity)."
However, the same was not true in the case of women, for whom "an inverse association" between occupational physical activity and risk of mortality was found. This association, however, was "non-significant," as Coenen and colleagues write.
The systematic review and meta-analysis are, their authors say, the first of their kind to emphasize the different health outcomes afforded by different domains of physical activity.
"This evidence indicates that physical activity guidelines should differentiate between occupational and leisure time physical activity," Coenen and team explain.
Yet they also caution that no causal relationships can as yet be established between high levels of occupational activity and a raised risk of death, since the studies they analyzed looked only at associations.
Further research should take a closer look at the mechanisms underlying the links observed thus far, the investigators note.