Chairs, the things we sit in, are like reishi mushrooms – they both have been around forever but were rarely used: only select individuals had the chance to use them. While the medical benefits of reishi mushrooms have been treasured in Chinese medicine for 2 millennia, only the emperor was permitted to take them.1 Chairs too have had a similar exclusivity. Chairs, although often represented in early Egyptian carvings, on ancient Greek vases, and in early Chinese murals, were thrones: only royalty got to sit.
Chairs became commonplace in the 16th century, at least in well-to-do homes; by the 17th century, even regular people had a chance to sit down. It is only in the last century that a significant portion of us have spent any length of our waking hours sitting down. In the course of human evolution, sitting is an abrupt change in behavior, one to which we are ill adapted.
These thoughts are sitting on my mind today after reading an October 2014 study by Sjögren et al. that reported a statistically significant association between sedentary behavior and telomere length.2
Telomeres are the "caps" on the end of each chromosome needed to stabilize the genome. Each time a cell divides, the telomere gets a little shorter, eventually getting so short that the cell dies. Telomere length is a predictor of risk for chronic disease and cancer, fast becoming the ultimate biomarker, a measure of how much lifespan we have left. Preventing telomere shortening is the goal of any intervention promising to improve health.3 Short telomeres are the hallmark marker of aging.4
Telomere length is a better predictor of heart disease than older biomarkers such as cholesterol. In July 2014, the British Medical Journal published a meta-analysis by Haycock et al. that included 24 studies involving 43,725 people. Participants with the shortest versus the longest telomeres had a relative risk for coronary heart disease of 1.54 (95% CI 1.30 to 1.83) in all studies, 1.40 (1.15 to 1.70) in prospective studies, and 1.80 (1.32 to 2.44) in retrospective studies.5
Sjögren measured telomeres in blood samples in a group of 49 overweight sedentary people before and after half of them took part in a 6-month exercise program.
The participants who exercised lost weight, and their lipid numbers improved.
What exercise did not do was lengthen telomeres. In fact, any increase in time spent exercising was associated with a nonsignificant trend toward shorter telomere length. The number of steps taken per day was not associated with any change in telomere length.
This is not what we would have guessed. Exercise is supposed to be good for people. This is such a basic tenet of modern belief that one might be tempted to discount Sjögren's results.
Here's where that history of chairs come in. Most of Sjogren's findings were not statistically significant, they were just trends; but the one strong and clear statistically significant finding was that reduced time spent sitting was significantly associated with increasing telomere length.
Our current faith in the benefits of exercise could be wrong. We may think that increasing exercise will benefit our patients' health, but the real benefit of exercise could be just that it reduces the time spent sitting. Modern sedentary behavior may be the problem, not a deficiency of time at the gym. Exercise's benefit may only be that it gets us to stand up. Exercise itself may even make the situation worse.6
For the 2 million years before there were comfortable chairs to sit in, humans expended huge amounts of energy moving about while looking for food. Data suggest that people living in simpler subsistence societies burn about twice the energy each day as we do.7
Repeated cell division is considered the main reason why telomere length decreases, but other causes contribute, in particular chronic exposure to DNA-damaging agents such as ultraviolet, especially oxidative stress and inflammation. Physiologic and psychological stress is also associated with decreased telomere length.8 Rigorous exercise increases oxidative stress in the body.
Admittedly, regular physical activity reduces risk of some age-related chronic diseases such as cardiovascular disease, cancer, and type 2 diabetes, but the actual reasons why are not yet understood.9 While we would want to assume that exercise either lengthens telomeres, or at the least prevents shortening, the data have been mixed; studies report that extreme exercise shortens telomeres.10
Some studies report positive associations between physical activity and telomere length. Cherkas et al. reported that increased physical activity was associated with increased telomere length equating to a 10-year decrease in biological age between active and inactive subjects.11 These differences are more pronounced in some studies; for example, ultramarathon runners compared with sedentary individuals have telomeres that suggest a 16-year difference in biological age.12 Telomere studies have, by and large, been retrospective and so they reveal associations, not cause and effect. The data from these studies might be interpreted to mean not that exercise makes us younger, but that sitting makes us older, or even that people who feel older sit more and don't run marathons.
Studies that compare athletes with sedentary individuals assume that the exercise is responsible for perceived benefits. Perhaps it is the other way around, that being sedentary is what causes the problem; exercise may be beneficial only because the individual sits less.
Back in naturopathic school, we spoke often of the concept of "vital force," or what in Chinese medicine is called jing, or "kidney essence": that different people are born with or possess varying levels of some inner vitality. Perhaps we were only referring to telomere length.
Does running ultramarathons lengthen telomeres; or are only people with long telomeres, or a great deal of vital force, interested in or capable of running such distances? Our goal may be less to achieve high-intensity exercise levels than to mimic the nonsedentary behavior of our chairless active ancestors.13,14
Several studies report an inverted-U relationship between physical activity and telomere length, wherein moderately active individuals exhibit longer telomeres compared with both sedentary and extremely active people. Those who exercised the least or the most had shorter telomeres than individuals in the "middle of the pack" where it comes to energy expenditure, even when effects of age, gender, and body weight were factored out.15 Moderate but steady activity perhaps should be the goal.
In 2012, van del Ploeg et al. reported an association of "sitting time" with all-cause mortality in a cohort of 222,497 Australians. Sitting for 11 or more hours per day, increased risk of dying by 40%.16
Sedentary behavior is also associated with increased cancer risk. An August 2014 meta-analysis, which combined data from 17 prospective studies to include a total of 857,581 participants, reported that sedentary behavior was significantly associated with a 20% increased overall risk of cancer (RR = 1.20, 95% CI = 1.12–1.28). This effect varied between cancer types with endometrial and lung having the largest significant increases in relative risk (RR 1.28 and 1.27 respectively).17
In a 2010 meta-analysis, sedentary behavior appeared as a significant etiologic factor for breast cancer. In 73 studies, physically active women had a 25% reduction in breast cancer risk when compared with the least active women. The strongest protection was found for moderate-intensity exercise, both recreational and household activities, sustained over a lifetime.18
This author spends a good portion of his workday sitting with patients and then compounds the situation by spending free time reading journals. This is a problem. This current study suggests that exercise, while it may keep us fit, does little to counter the overall effect of such a sedentary life. That quick workout at the gym that we were feeling so proud of may only make things worse.
Thus we need to find ways to not only reduce our own sedentary behaviors but also model this approach for our patients. The lack of an association between daily steps and telomere length is disheartening. Modern American men now average about 5000 steps per day, while men living in Amish farming communities take about 3.5 times that, nearly 18,400 steps per day.19,20 The measure of possible benefit might not be the energy expenditure as the limited time spent sitting that we should be counting.
It would have been easy to clip a pedometer to each patient accompanied with a daily step goal. This is still not a bad idea, but if our aim is to reduce time spent sitting, it isn't what we need.
The easiest approach may be to simply stand up while at work. This article was written while I was standing up at my new work desk. Actually I've created three stand-up work-stations for myself: a fancy one purchased online in my home office, a kitchen counter at home, and a pair of cardboard boxes propped on top of my office desk to elevate my computer to a comfortable height. It took a little getting used to, but it has been an easy enough habit to form.
1. The ganoderma history [online article].Ganoderma lucidum. http://www.ganodermalucidum-reishi.com/ganoderma-lucidum/the-ganoderma-history.html.
2. Sjögren P, Fisher R, Kallings L, Svenson U, Roos G, Hellénius ML. Stand up for health – avoiding sedentary behaviour might lengthen your telomeres: secondary outcomes from a physical activity RCT in older people. Br J Sports Med. 2014 Oct;48(19):1407–1409.
3. Alschuler L. Optimal longevity hinges on telomeres. Nat Med J. June 2013;5(6). Available at http://naturalmedicinejournal.com/journal/2013-06/optimal-longevity-hinges-telomeres.
4. López-Otín C, Blasco MA, Partridge L, et al. The hallmarks of aging. Cell. 2013;153(6):1194–1217.
5. Haycock PC, Heydon EE, Kaptoge S, Butterworth AS, Thompson A, Willeit P. Leucocyte telomere length and risk of cardiovascular disease: systematic review and meta-analysis. BMJ. 2014 Jul 8;349:g4227. doi:10.1136/bmj.g4227.
6. Sjögren et al. Op cit.
7. Hayes M, Chustek M, Heshka S, Wang Z, Pietrobelli A, Heymsfield SB. Low physical activity levels of modern Homo sapiens among free-ranging mammals. Int J Obes Relat Metab Disord. 2005;29:151–156.
8. Ludlow AT, Ludlow LW, Roth SM. Do telomeres adapt to physiological stress? Exploring the effect of exercise on telomere length and telomere-related proteins. Biomed Res Int. 2013;2013:601368. doi:10.1155/2013/601368. Epub 2013 Dec 24. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3884693/pdf/BMRI2013-601368.pdf.
9. Ludlow AT, Roth SM. Physical activity and telomere biology: exploring the link with aging-related disease prevention. J Aging Res. 2011;2011790378.
10. Ludlow AT, Ludlow LW, Roth SM. Do telomeres adapt to physiological stress? Exploring the effect of exercise on telomere length and telomere-related proteins. Biomed Res Int. 2013;2013:601368. doi: 10.1155/2013/601368. Epub 2013 Dec 24. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3884693/pdf/BMRI2013-601368.pdf.
11. Cherkas LF, Hunkin JL, Kato BS, et al. The association between physical activity in leisure time and leukocyte telomere length. Arch Int Med. 2008;168(2):154–158.
12. Denham J, Nelson CP, B. J. O'Brien et al. Longer leukocyte telomeres are associated with ultra-endurance exercise independent of cardiovascular risk factors. PLoS ONE, vol. 8, no. 7, 2013.
13. Du M, Prescott J, Kraft P, et al. Physical activity, sedentary behavior, and leukocyte telomere length women. Am J Epidemiol. 2012;175(5):414–422.
14. Kim JH, Ko JH, Lee DC, et al. Habitual physical exercise has beneficial effects on telomere length in postmenopausal women. Menopause. 2012;19(10):1109–1115.
15. Ludlow AT, Zimmerman JB, Witkowski S, Hearn JW, Hatfield BD, Roth SM. Relationship between physical activity level, telomere length, and telomerase activity. Med Sci Sports Exerc. 2008;40(10):1764–1771.
16. Van der Ploeg HP1, Chey T, Korda RJ, Banks E, Bauman A. Sitting time and all-cause mortality risk in 222 497 Australian adults. Arch Intern Med. 2012 Mar 26;172(6):494–500. doi:10.1001/archinternmed.2011.2174.
17. Shen D, Mao W, Liu T, et al. Sedentary behavior and incident cancer: a meta-analysis of prospective studies. PLoS One. 2014 Aug 25;9(8):e105709. doi:10.1371/journal.pone.0105709. eCollection 2014.
18. Friedenreich CM. The role of physical activity in breast cancer etiology. Semin Oncol. 2010 Jun;37(3):297-302. doi: 10.1053/j.seminoncol.2010.05.008.
19. Bassett DR, Schneider PL, Huntington GE. Physical activity in an Old Order Amish community. Med Sci Sports Exerc. 2004;36:79–85.
20. Bassett DR, Jr, Wyatt HR, Thompson H, Peters JC, Hill JO. Pedometer-measured physical activity and health behaviors in United States adults. Med Sci Sports Exerc. Epub 16 March 2010.
Jacob Schor, ND, FABNO, has practiced as a naturopathic physician in Denver, Colorado, with his wife, Rena Bloom, ND, since they graduated from National College of Naturopathic Medicine in 1991. He was humbled in 2008 when presented with the Vis Award by the American Association of Naturopathic Physicians (AANP). He has had the honor of serving the members of the Oncology Association of Naturopathic Physicians as a board member and currently as president. Dr. Schor began a term on the AANP's board of directors in January 2012. He is a frequent contributor to, and associate editor of, the Natural Medicine Journal.