Walking 2019

Jacob Schor ND, FABNO

Back when I was 16 years old, I had a friend named Margie who lived in Berkeley, California; and because of this and a rather intriguing personality, she acquired a special place in my mind and heart. Once while riding the Long Island Railroad toward the city, she quoted the opening stanza of a poem by W. H. Davies to me. It is a measure of how blank the palette my youthful mind was, perhaps, my wish to emulate her perceptive grasp on life, or a craving for a similarly strong view on how to lead life that I still remember that quote to this day:

“Now shall I walk or shall I ride?

‘Ride,’ Pleasure said;

‘Walk,’ Joy replied.”¹

These lines have risen from memory ever since when I’ve faced with a choice of transportation. If I can, I walk. A half century later, I still find the same answer surfaces in my mind.

These days everybody knows that walking is good for you. Fitbit’s are everywhere, and it seems to be the rarity to find a person who isn’t trying to reach their 10,000 steps per day.

A new study from Harvard, while it confirms that walking is good for our overall health, has brought into question this distance goal. I-Min Lee and colleagues at the T.H. Chan School of Public Health conducted a prospective cohort study testing the association between exercise, measured as steps per day, with all-cause mortality. Their results were published in JAMA (May 28, 2019).

Their study cohort started with 18,289 women who are part of the Women’s Health Study. The women were asked to wear an accelerometer during waking hours for seven days during 2011 and 2015. Basically, an accelerometer is the modern version of a pedometer. Only women who wore the device for 10 hours per day or more on four or more days, without malfunction, were included. As a result, only 16,741women were included in the final data analysis. The mean age of these women was 72.²

The only outcome measure that Lee et al looked at was death; that is, they calculated risk of mortality. Deaths were ascertained through either family members or public records. They compared risk of dying and sought associations with how many steps the women took during the week they wore their accelerometers.

During an average follow-up of 4.3 years, 504 women in the cohort died. The risk of dying was inversely associated with number of steps taken per day. Risk of death significantly decreased with increasing number of daily steps. The women were divided into 4 quartiles by number of steps and intensity of exertion interpreted from frequency of steps. Those in the first quartile took an average of 2,718 steps per day, in the second quartile, 4,363 steps/day, in the third, 5,905 and the fourth quartile 8,442 steps/day.

If the relative risk of dying for those women in the lowest quartile of steps per day is set to 1.0, the risk decreased significantly for each quartile; risk decreased to 0.51 for those in the second quartile, and 0.44 for the third, and 0.33 for fourth (P < .01) (adjusted for age and wear time). Further adjustment for potential confounders weakened the associations only slightly, to 1.00, 0.59, 0.54, and 0.42, respectively (P < .01).

The absolute rate reduction comparing those women in the fourth quartile to those in the first quartile was 9.3 deaths per 1000 person-years. For every additional 1000 steps/day, the hazard ratio declined by 15%. Additional adjustment for BMI, hypertension, high cholesterol, and diabetes shifted quartile HRs to become more similar to those adjusted for age and wear time only (1.00, 0.54, 0.47, 0.34; P < .01). When adjusting for stepping intensity in addition to confounders, associations were attenuated but all remained significant (HRs per quartile: 1.00, 0.68, 0.68, 0.58; P < .01).

The largest impact was the 41% reduction in mortality rates between women in the first and second quartile, that is women who walked only 2,700 steps per day compared to 4,400 steps. Mortality rates continued to decrease with increasing steps up to approximately 7500 steps/day at which point benefit levels off. Stepping intensity, basically how fast one walked, had relatively little impact. Number of steps mattered more than intensity.

This is kind of a big thing, that simply walking could have such a big impact. People shouldn’t sit around all day; they should get up and go for a walk. At this point this is a no-brainer and everyone kind of knows this.

Many of our patients have gotten a bit obsessed with step counting. It’s beyond fashionable. Fitbit sold 14 million devices between 2010 and 2018.³ Everyone who owns a Fitbit or uses any other step tracker device or application is certain that their goal is to walk 10,000 steps per day. It is time to erase this 10,000-step goal. It’s not based on evidence.

The whole 10,000-step target apparently originated with Yamasa, a Japanese company, that designed a pedometer in 1965 that they called the ‘manpokei,’ a name that translates as 10,000 steps meter.⁴ At the time there was some thought that 10,000 steps per day was necessary to decrease risk of coronary heart disease. This was more of a marketing idea than a medical finding.

There is nothing new about step counting. It has been used as a method to measure distances since ancient times. The word mile is Latin in origin, from milia passuum, or one thousand paces.⁵ If one knew how to count, one could create accurate maps and know where they were. The idea of using mechanical aids to count steps goes back to DaVinci. Thomas Jefferson had a pedometer custom made for him while he lived in Paris and noted that he took fewer steps to walk a mile in cold weather than warm.⁶ He sent a pedometer to James Madison as a gift in 1788.⁷

There is scant evidence that informs us how many steps are actually needed to improve health. A 2018 meta-analysis by Oja et al that examined walking intervention trials reported improvements in cardiovascular risk factors with increasing steps. Yet they were not certain that the results they examined were significant.⁸ Kelly et al’s 2014 meta-analysis of observational studies reported amounts of walking and bicycling were inversely related to mortality rates but reported their conclusions in MET hours per week.⁹ In 2017 Stamatakis et al reported that faster paced walking was also inversely related to mortality rates.¹⁰

There have been a number of specific mortality studies worth noting. In 2015 Dwyer et al reported number of steps and all-cause mortality on a cohort in Tasmanians and reported a linear relationship between increasing daily steps and reduced mortality risk (n = 2,576). Compared to those described as sedentary, those taking 10,000 steps per day had a 46% lower risk of mortality in the decade of follow up. Those who increased their daily steps over the course of the study also experienced substantial reduction in mortality risk. A 1000-step/day increment was associated with 6% risk reduction.¹¹ In a 2018 British study by Jeffries et al, (n= 1,655) on older men, each 1000-step/day increment was associated with a 14% reduction in mortality risk.¹²

Other step-counting studies have reported lower risk of dysglycemia, decreases in adiposity, and improved insulin sensitivity with increasing steps.¹³ Shifts in mortality risk generally outweigh these sorts of improvements in patients’ minds.

This current study by Lee et al was substantially larger than prior research trials, and pedometer technology has only become more sophisticated over time. Based on these findings, the evidence suggests health benefits, at least in terms of mortality, level off at about 7,500 steps per day.

This may pose a problem as the 10,000-step goal is now so cemented in public belief, suggesting anything less to patients may only lead to your patients to question your expertise. The longer I think about this, the less sure I am that this is the right battle to have. Let them continue to think their goal is 10,000; and if they confess that they only reach 7,500 steps, then explain the truth to them.

Where the real pay-off will be is in getting the couch-potatoes, the lowest quartile of daily steppers, those who walked 2,700 steps or less per day to get up and move more. Moving them from sedentary to moderate activity will have the greatest effect on health. We should put our effort where it will make the most difference.

References

1. The rest of the poem: Now what shall I — / Stay home or roam? / “Roam”, Pleasure said;/

And Joy — “stay home.”/Now shall I dance, / Or sit for dreams? / “Sit,” answers Joy; / “Dance,” Pleasure screams./ Which of ye two/ Will kindest be? / Pleasure laughed sweet, / But Joy kissed me.

2. Lee IM, et al. Association of Step Volume and Intensity With All-Cause Mortality in Older Women. JAMA Intern Med. 2019 May 29.

3. Statista. Number of Fitbit devices sold worldwide from 2010 to 2015. 2016. http://www.statista.com/statistics/472591/fitbit-devices-sold/. Accessed 15 July 2016

4. Hatano Y. Pedometer-assessed physical activity: Measurement and motivations. In: Presented at 48th annual meeting of the American College of Sports Medicine (May 30–June 3), 2001, Baltimore, MD; 2001.

5. Bassett DR, et al. Walking and measurement. Med Sci Sports Exerc. 2008;40(7 Suppl):S529–S536

6. Dumbauld E. Thomas Jefferson: American tourist. Norman: University of Oklahoma Press; 1946.

7. Wilson DL, Stanton L, editors. Jefferson Abroad. New York: Modern Library; 1999.

8. Oja P, et al. Effects of frequency, intensity, duration and volume of walking interventions on CVD risk factors: a systematic review and meta-regression analysis of randomised controlled trials among inactive healthy adults. Br J Sports Med. 2018;52 (12):769-775.

9. Kelly P, et al. Systematic review and meta-analysis of reduction in all-cause mortality from walking and cycling and shape of dose response relationship. Int J Behav Nutr Phys Act. 2014;11:132.

10. Stamatakis E, et al. Self-rated walking pace and all-cause, cardiovascular disease and cancer mortality: individual participant pooled analysis of 50 225 walkers from 11 population British cohorts. Br J Sports Med. 2018;52(12):761-768.

11. Dwyer T, Pezic A ,Sun C, etal. Objectively measured daily steps and subsequent long term all-cause mortality: the Tasped Prospective Cohort Study. PLoS One. 2015;10(11):e0141274.

12. Jefferis BJ, et al. Objectively measured physical activity, sedentary behaviour and all-cause mortality in older men: does volume of activity matter more than pattern of accumulation? Br J Sports Med. 2018; bjsports-2017-098733.

13. Dwyer T, et al. Association of change in daily step count over five years with insulin sensitivity and adiposity: population based cohort study. BMJ. 2011;342:c7249.