Physical activity at work – detrimental or beneficial for health?

Occupational physical activity promotes longevity – new findings published today in Lancet Public Health.

Fisherman with cod in Lofoten, Norway
Fishermen, farmers and construction workers have jobs that are often physically demanding, but all the physical activity can be positive. Photo: Shutterstock

A new study from the Norwegian School of Sport Sciences and the Norwegian Public Health Institute found that physical activity performed during work promotes longevity in men.

It is well known that leisure time physical activity promotes health. However, a 'physical activity paradox' has been proposed suggesting that occupational physical activity may contribute to an increased mortality risk in those with physically active occupations.

"Over the last decade or so, several epidemiological studies have suggested that moderate to high levels of occupational physical activity may increase mortality risk, especially from cardiovascular disease in men" said lead researcher Dr Knut Eirik Dalene, Postdoc at the Norwegian School of Sport Sciences.

"However, to disentangle the causal effect of physical activity at work when comparing people in different occupations is difficult, as occupational physical activity is connected with a host of other factors that have well-established impacts on mortality risk" he says.

High quality data on several such key factors were available to the researchers in this large study which followed almost 440 000 Norwegian men and women for an average of 28 years, during which 74 203 died.

Simple analysis did indeed suggest that men in sedentary occupations had higher life expectancies than men with moderate to high levels of occupational physical activity. However, when the researchers statistically adjusted for factors such as education level, income, smoking and leisure time physical activity, estimates were reversed.

This means that when factors influencing the association between occupational physical activity and longevity ‘are held equal’, men in occupations characterised by walking, walking and lifting, and heavy labour had life expectancies that were up to 1.7 years longer than men with sedentary occupations.

"These results suggest that all physical activity is beneficial for reducing the risk of death regardless whether physical activity is performed during work or leisure time" says senior author Professor Ulf Ekelund at the Norwegian School of Sports Sciences and the Norwegian Institute of Public Health.

"The new physical activity guidelines from WHO in 2020 did not consider the importance of occupational physical activity due to lack of robust evidence" says Ekelund, who was also member of the WHO guideline development group. Therefore, these novel results may inform future guidelines on physical activity for public health.

"While it is clear that men reporting higher occupational physical activity also die earlier than those in sedentary occupations, this is apparently not due to their levels of physical activity at work but rather explained by a number of socio-economic and lifestyle factors" says Dalene and Ekelund, who also point out that studies investigating the effect of different combinations of occupational physical activity, leisure time physical activities, exercises and physical fitness on health outcomes are highly warranted.

 

Author: Dr Knut Eirik Dalene
Department of Sports Medicine
the Norwegian School of Sports Sciences