A drywall finisher walks 18,000 steps a day, carries sheets up stairs and spends hours with her arms over her head. Her phone's fitness app gives her a gold badge every afternoon. Her doctor tells her to get 150 minutes of exercise a week. Is she already doing it, many times over?
The intuitive answer is yes: movement is movement. A growing body of research says it is not that simple. In large studies, people who are active in their free time live longer and have fewer heart attacks, while people whose jobs are physically heavy do not get the same benefit, and in some studies do worse. Researchers call this the physical activity paradox. This piece is for cooks, cleaners, builders and the owners who run their shifts: what the studies found, why heavy work might not act like exercise, how sure anyone can be, and what is sensible to do about it.
What the big studies found
Copenhagen, 104,046 people. Andreas Holtermann and colleagues followed adults from the Copenhagen General Population Study for a median of ten years (published in the European Heart Journal in 2021). People reported how active they were in their leisure time and at work. Compared with low leisure activity, high leisure activity came with about 23% fewer heart attacks, strokes and other major cardiovascular events. Work went the other way: compared with low occupational activity, high activity came with about 15% more events and very high activity with about 35% more, after adjusting for lifestyle, health, living conditions and income and education.
A pooled study of 590,000 people. Pieter Coenen and colleagues pooled individual data from 22 cohort studies in the British Journal of Sports Medicine (2024), with up to 590,497 people followed for an average of 23 years. More leisure activity went with lower mortality: 21% lower for men and 25% for women. For work, men in highly active jobs had about 12% higher mortality than men in sedentary jobs; for women there was no clear link either way. When the authors also adjusted for income, the men's figure dropped to about 2%.
Sick leave. An earlier Danish study by Holtermann's group (2012) of 7,144 employees found the same split for long-term sick leave: more leisure activity, less sick leave; more physical activity at work, more.
Leisure activity keeps showing up as good for the heart. Heavy work does not, and the reasons are about how the work is done, not that moving is bad.
Why heavy work might not count as exercise
In a 2018 editorial in the British Journal of Sports Medicine, Holtermann, Niklas Krause, Allard van der Beek and Leon Straker set out six possible reasons. They are hypotheses, not findings, but each one maps onto a shift most crews will recognise:
1. Wrong intensity, too long. Fitness improves with short bouts at a high effort (about 60 to 80% of a person's aerobic capacity). A shift is the opposite: hours at a moderate load. Over an eight-hour day, averages above roughly a third of capacity may strain the heart rather than train it.
2. Heart rate stays up all day. A 40-minute run raises your heart rate and then it falls. A heavy shift keeps it raised for hours, and a high 24-hour heart rate is a risk factor in itself.
3. Lifting and static postures raise blood pressure. Holding a sheet overhead, carrying stock, crouching over a floor: these lift blood pressure while you do them, and long exposure may keep it higher after work.
4. Not enough recovery. Seven to twelve hours a day, several days running, with short breaks: in sport this would be called overtraining.
5. Little control. The worker rarely sets the pace, the schedule, the heat or when to drink and rest. A runner who feels bad slows down; a line cook on a Friday rush can't.
6. Inflammation that doesn't settle. Markers of inflammation rise during effort and fall with recovery. Long days back to back may keep them raised, one suspected route to hardened arteries.
Two of those (recovery and control) are things a crew lead can change on the rota. The authors' later idea, which they call Goldilocks Work, is that physical work could be designed to be "just right": varied enough, with enough recovery, to build capacity instead of wearing it down. It is a design principle for researchers and employers, and the trials so far are small feasibility studies.
What this does not show
It does not show that physical work is bad for you. Every big study here is observational. People in heavy jobs differ from people in desk jobs in income, education, smoking, diet, housing, stress and access to care, and adjusting for those is never complete. The 2024 pooled study is the clearest example: adding income shrank the men's excess risk from 12% to about 2%. Some researchers argue that much of the paradox is this kind of leftover difference between groups.
Activity was mostly self-reported. People were asked how active their job was, not measured with devices. A cleaner and a roofer may both answer "heavy".
The results are not the same for everyone. In the pooled study, women in active jobs showed no excess risk. The Copenhagen and Danish data are from one country with free health care and long holidays.
It does not mean you should stop moving at work. No study suggests that sitting still on shift would be better. The finding is that work activity does not replace leisure exercise, not that it is the problem on its own.
Global guidance counts all activity. The World Health Organization's 2020 guidelines count activity at work, in transport, at home and in leisure toward the weekly targets, while noting that the evidence on different domains is still developing.
What is sensible for crews on their feet
None of this is a prescription. If you have a heart condition or high blood pressure and a physical job, ask your doctor; the editorial notes the extra risk looked largest in workers with low fitness or existing heart disease. For everyone else, the research points in a few practical directions.
For the person doing the work
Don't count the shift as your workout. The steps are real, but the evidence says they are not the kind of activity that builds fitness. A short, harder bout on your own terms (a brisk 20-minute walk or cycle, a few sets of strength work) is different in kind from a long day at moderate load.
Strength helps the job itself. In a Danish trial, slaughterhouse workers with chronic arm and shoulder pain did ten minutes of strength training three times a week at work for ten weeks. Their work ability held up, while it fell in the group given ergonomics advice instead. One small trial, but it fits the idea that a stronger worker carries the same load at a lower share of their capacity.
Protect the recovery. Sleep and the days off do more work than they seem to. A run on a day off after a hard week is not always the right call; rest is part of the point.
For the owner or crew lead
Rotate the heavy jobs. If the same person unloads every delivery, carries every sheet or scrubs every floor, swap tasks across the week so heavy and light work alternate. On a team board, put names on the heavy jobs and look at who has had them three days running.
Give the breaks the law requires, and take them. Rest breaks inside a long shift are the cheapest recovery there is. Our piece on meal and rest breaks by state lists what each state requires.
Keep rest between shifts. A close followed by an open leaves little time to recover; see Clopening shifts.
Hand back some control. Let people choose the order of their tasks where the job allows, and make water and shade easy to get to on hot days. Control over pace is one of the six reasons on the list.
Put names on the heavy jobs, see who has carried them all week, and plan shifts with rest between them, from one phone app.
See it for constructionSources
Holtermann A., Krause N., van der Beek A.J., Straker L., "The physical activity paradox: six reasons why occupational physical activity (OPA) does not confer the cardiovascular health benefits that leisure time physical activity does", British Journal of Sports Medicine 52:149-150 (2018). Full text, CDC Stacks
Holtermann A., Schnohr P., Nordestgaard B.G., Marott J.L., "The physical activity paradox in cardiovascular disease and all-cause mortality: the contemporary Copenhagen General Population Study with 104 046 adults", European Heart Journal 42(15):1499-1511 (2021). Record
Coenen P. et al., individual participant data meta-analysis of occupational and leisure-time physical activity and mortality, British Journal of Sports Medicine 58:1527-1538 (2024), and the authors' summary on the BJSM blog (October 2024). Blog
Holtermann A. et al., "The health paradox of occupational and leisure-time physical activity", British Journal of Sports Medicine 46:291-295 (2012). Article
Holtermann A., Mathiassen S.E., Straker L., "Promoting health and physical capacity during productive work: the Goldilocks Principle", Scandinavian Journal of Work, Environment & Health (2019). Article
Sundstrup E. et al., "Workplace strength training prevents deterioration of work ability among workers with chronic pain and work disability: a randomized controlled trial", Scandinavian Journal of Work, Environment & Health 40(3):244-251 (2014). Record
World Health Organization, Guidelines on physical activity and sedentary behaviour (2020). Guidelines