Aside from rather unpleasant calorie deprivation, scientific evidence points to regular physical activity as being an important means for lengthening human “health span”. (Health span differs from life span because it measures the number of healthy years that a person lives, in contrast to crude longevity.) Consequently, recent online claims by some occupational health “experts” that workers whose jobs entail higher physical demands are also at heightened risk for cardiovascular disease (C.V.D.), seem paradoxical. A few have gone further still by asserting that strenuous leisure-time activity on the part of manual workers, including conventional “work outs”, places them at an even higher C.V.D. risk. Being ardent fitness advocates, Spanking FIT felt immediately obligated to question the scientific validity of these claims.
Do physically demanding jobs heighten C.V.D risks?
In 2013, considerable international media coverage was given to a publication presented to the European Society of Cardiology (E.S.C.) Europrevent Congress by D. Panagiotakos, M.D.. In it he asserts that manual workers are more cardiovascular disease-prone than sedentary ones. (“Physically demanding occupation is associated with higher likelihood of a non-fatal acute coronary syndrome or ischemic stroke: a case/ case-control study” published in the European Journal of Preventive Cardiology, April 2013; 20, supp 1.) Time Magazine instantly picked up on it and ran the following headline that very same month in an online health news segment: “Working Too Hard? Physically Demanding Jobs Tied to Higher Risk of Heart Disease”. The reported results were, as indicated, based on a case-control study involving 250 acute coronary syndrome (A.C.S.) patients and another 250 ischemic stroke event (I.S.E.) patients who were matched with controls according to age and gender. Researchers reported that subjects who had developed specifically those health issues were also more likely to be engaged in physically demanding occupations than their control counterparts. Moreover, they reported these results at a rather high level of statistical significance. Based on the statistical technique known as logistic regression and after allegedly “controlling” for a long list of covariates (influencing factors) such as age, gender, B.M.I., etc., researchers concluded that workers with heart problems were more likely to be employed in more physically demanding jobs. Upon careful review, Spanking FIT ascertained that this research did not take into account the fitness status of its participants. It is clear that if a greater proportion of the less physically fit existed within the physically demanding work groups, results could be easily skewed in favor of more sedentary workers. Consequently, Spanking FIT searched for studies of a similar nature which also took into account worker physical fitness factors. I came up with this significant one: ”Physical demands at work, physical fitness, and 30-yr. ischemic heart disease (I.H.D.) and all-cause mortality in the in the Copenhagen male study” by A. Holtermann, et al. and published in Scandinavian Journal of Work, Environment, & Health, 2010, 36 (5): 357-65. While limited to males only (specifically 5,249 male workers, 40-59 years of age), this research study met criteria by utilizing laboratory VO2 Max measurements taken during a cycling test. VO2 Max is a commonly used measure of a subject’s physical fitness. Next, they broke down their sample of workers having high physical demand jobs into three different fitness levels: (1) “least fit” (bottom quintile) (2) “moderately fit” (the three mid quintiles) and “most fit” (top quintile). Using the stat technique of Cox proportional hazard regression, they compared the risks of I.H.D. mortality for each of the above groups with those individuals having the same fitness levels, but in low physical demand jobs. Their discovery: I.H.D. risks were greater for the “least fit” and “moderately fit” manual workers only. Among the “most fit”, no significant differences between the two types of worker were detected based on a sample of 192 manual workers and 233 sedentary ones. In the words of the authors, “being physically fit protects against adverse cardiovascular events”. Researchers, however, did not adequately explain why manual work seems to adversely affect the less physically fit in this disproportionate manner. The answer may have more to do with potential differences in quality of health care and the resulting treatment disparities, rather than the effects of manual work on human physiology. For example, while including hypertension treatment in their model, researchers did not include cholesterol treatment. If the manual workers did not receive the same quality of health care attention to their cholesterol problems as the sedentary workers did, that fact alone could place them at greater risk of death from I.H.D.. The latter issue aside, these findings emphasize the importance for all workers to “get into shape” and remain that way.
Is it hazardous for manual workers to work out?
It has even been asserted by a few “experts’ that leisure-time exercise may be detrimental to the cardiovascular health of manual workers and place them at heightened risk of such coronary events as acute myocardial infarction, unstable angina, etc. Among adherents to this viewpoint is Prof. E. Clays of Ghent University, Belgium and some of her colleagues. They published this opinion in “The association between leisure time physical activity and C.H.D. among men with differing physical work demands: a prospective cohort study” which appeared in in European Journal of Epidemiology 2013; 28 (3): 241-47. Prof. Clays et al. reported results using data from BELSTRESS, a large scale epidemiological study that is a part of the European cooperative study on job stress, absenteeism, and coronary heart disease (J.A.C.E.). Their analysis was performed also using the stat tool of Cox proportional hazard regression. They reported that among workers engaged in ”high physical activity” jobs, those who further engaged in “medium/ high” leisure-time activities were at significantly elevated risk of experiencing a coronary event, compared to workers who engaged in “low” leisure-time physical activity. Hence, their implication is that leisure time physical activity may be detrimental to manual worker health. However, upon careful examination of their analysis, Spanking FIT observed that researchers made an error which commonly occurs in the medical field: reporting based on results that are not statistically significant. (After “correcting” for covariates in their model, at least one of their computed hazard ratios was not statistically significant making their comparisons invalid.) Furthermore, the mean (average) follow up period on workers in their study was only 3.15 years.
On opposite side of the debate, Spanking FIT identified: ”The interplay between physical activity at work and during leisure time-risk of ischemic heart disease and all-cause mortality in middle-aged Caucasian men” by A. Holtermann published in Scandinavian Journal of Work, Environment, & Health, 2009; 35 96): 466-74.
These published results were based on the previously cited Copenhagen Male Study for ischemic heart disease mortality which consisted of 5,249 male workers between the ages of 40 and 59 years old. After correcting for a large set of covariates including age, B.M.I., blood pressure, etc., researchers reported statistically significantly lower risks for workers in “high work demand” jobs who also engaged in “medium/ high” leisure activities compared to “low” leisure activity workers. Their results, in contrast to the previous ones, support the theory that all workers, including those in high work demand jobs, may benefit from leisure-time exercise including tennis, swimming, long distance running, etc., Their conclusion also strongly agrees with the Spanking FIT philosophy.
Fitness Experts Consider Occupation
It is quite evident that despite somewhat sensationalistic claims to the contrary, physical fitness activities benefit workers of all varieties, including so-called manual workers who engage in physically demanding jobs. Also, it is a common mistake on the part of most fitness “experts” to assume that the “work out club” consists of sedentary workers only with desk jobs. Far too many of them are limiting their audience by doing so.
It’s essential that recommended fitness routines be tailored to various occupations. It makes little sense to recommend the same standardized gym or online workout for everyone. For example, the worker whose job requires heavy lifting such as a mason or a roofer, is well-advised to focus on aerobic exercise, as opposed to anaerobic exercise, during his/ her leisure-time exercise routine. It is also vital that recommended and performed workouts “balance out” the stresses and the strains of work-related activities to avoid occupational injury. Workers whose jobs require lifting or frequent movement may benefit by performing exercises in “Athletes Avoid Inguinal Hernia“, Spanking FIT, Jan. 2017. Far less stressful, but equally effective abdominal exercises explained in “Science on Six-Pack-Abs”, Spanking FIT, Jan. 2017 may replace the traditional “sit up”.
Prominent health organizations such as the U.S. Centers for Disease Control (C.D.C.), the American Heart Association, and the U.S. National Institutes of Health (N.I.H.) have all formulated guidelines and recommendations for physical activity as a means of improving public health. However, none presently tailor them according to worker occupation. In my opinion, it is extremely important that such guidelines serve the needs of all workers including those in more physically demanding jobs. Pertinent data for producing these guidelines may be obtained from large scale studies such as the ones previously cited by Spanking FIT (e.g., the Copenhagen Male Study). A careful examination of specific elements of the leisure-time activities of those achieving greatest health span could provide valuable input. An ultimate goal would be development of computer software whereby individual work-related activities are input with resulting output being a list of recommended leisure-time physical activities. Although driven by computer, recommendations should be flexible enough to accommodate human enjoyability factors and freedom of choice.
Finally, it goes without saying that more and more women are assuming physically demanding jobs in the workplace. Consequently, future research needs to be more inclusive in this respect. Thank you very much for your interest in this topic. As usual, I look forward to your valuable feedback. Dr. Garrett
Featured photo credit: https://www.flickr.com/photos/91173606@N00/5685673690/in
Creative commons license: https://creativecommons.org/licenses/by-nc-sa/2.0/