Stop the escalators: using the built environment to increase usual daily activity

Abstract

Background

Obesity is an epidemic in the United States. Two-thirds of the population is overweight and does not get enough exercise. Eastern cities are full of escalators that transport obese Americans to and from the subway. Walking stairs is a moderate activity requiring 3–6 metabolic equivalent tasks (METS) and burning 3.5–7 kcal/min. We determined the caloric expenditure and potential weight change of the population of one eastern city if all the subway riders walked the stairs rather than ride the escalators.

Methods

There are 5,000,000 daily journeys made on the New York City Subway. Subway entrances include a stairway or escalator of approximately 25 steps. Each step up requires 0.11–0.15 kcals; each step down requires 0.05 kcals. To lose one pound requires burning 3500 kcals. We assumed each rider made a round trip so about 2.5 million individual people ride the subway each day.

Results

By walking stairs rather than riding escalators, the riders of the New York Subway would lose more than 2.6 million pounds per year.

Discussion

The average subway rider would lose about one pound per year. While this may sound insignificant, in one decade the average subway rider would lose 10 pounds, effectively reversing the trend in the United States of gaining 10 pounds per decade. This conservative estimate of the number of stairs ascended daily means that subway riders might lose even more weight. We believe that this novel approach might lead to other public and private efforts to increase physical activity such as elevators that only stop on even numbered floors, making stairwells more attractive and well lit, and stopping moving sidewalks. The built environment may support small, incremental changes in usual daily physical activity that can have significant impact on populations and individuals.

Background

Obesity is an epidemic in the United States. Increasing steadily over the past quarter century, 32%–35% of the US population are now obese, and two-thirds are overweight.¹ The prevalence of obesity in young people has more than doubled.² Obesity rates are higher among non-Hispanic Blacks and Mexican Americans.² Additionally, over half of the US population does not get enough exercise.³ Physical activity has been shown to have a positive impact on health and longevity.⁴ Diez Roux et al⁵ and Cohen et al⁶ found that the availability of common recreational spaces such as parks and sports facilities were related to increased activity. The built environment can incorporate “usual daily activities” as a potential source for increased exercise and energy expenditure.

While traveling on the East Coast we were struck by the number of escalators that transport overweight Americans up and down from the street level to the subway system. Walking up and down stairs is reported as a moderate activity requiring 3–6 METS and burning 3.5–7 kcal/min.⁷ We determined to measure the impact of stopping the subway escalators on caloric expenditure and weight of the population of one eastern metropolitan area.

Methods

We obtained the number of daily subway riders in New York City. There are 5,000,000 riders on the New York City Transit Subway system each day.⁸ (Approximately 1.5 billion per year.) Each rider must enter and exit the subway via the stairs or escalator. There are 169 escalators on the NYC subway system.⁹ Based on our observations, we estimated that each entrance includes a stairway escalator of approximately 25 steps, with many escalators moving 50–75 steps. Therefore each rider descends and ascends approximately 25 steps. Each step up requires 0.11–0.15 kcals, and each step down requires 0.05 kcals.^10,11 To lose one pound requires burning 3500 kcals.¹² We calculated the number of calories burned and the subsequent pounds lost if the New York City Subway stopped their escalators. We assumed each rider weighed the standard 70 kg.¹³ And we assumed each rider made a round trip (2 entrances and 2 exits) so about 2–2.5 million individual people ride the subway each day.

Results

By walking the stairs rather than riding the escalators, the riders of the New York City Transit Subway would lose more than 2.6 million pounds per year.

$$\begin{array}{l}(5,000,000\text{riders}\times 25\text{stairs}up\times 0.15\text{kcal}/\text{stair})+(5,000,000\text{riders}\times 25\text{stairs}down\times 0.05\text{kcal}/\text{stair})\\ =25,000,000\text{kcal}/\text{day}÷3500\text{kcal}\\ =7142\text{lb}/\text{day}\times 365\text{days}\\ =2,607,142\text{pounds per year}.\end{array}$$ (1)

The population of subway rides would lose over 2.6 million pounds per year. The subway includes approximately 2–2.5 million riders so each individual rider will lose approximately 1 pound each year.

Discussion

The average subway rider would lose about one pound per year. While this may sound insignificant, in one decade the average subway rider would lose 10 pounds, effectively reversing the trend in the United States of gaining 10 pounds per decade. This conservative estimate of the number of stairs ascended daily and the conservative estimate of caloric cost per step means that it is likely that subway riders would lose even more weight. Other cities with subways may enjoy similar results. The Washington DC subway system includes 86 subway stations with 588 escalators.¹⁴

We believe that this novel approach might lead to other public and private efforts to increase physical activity such as elevators that only stop on even numbered floors, making stairwells more attractive and well lit, and stopping moving sidewalks. While it may not be feasible to stop the escalators in New York City, this short analysis points out how even small changes in the built environment may change usual daily activity leading to increased exercise, and improved fitness. The built environment provides important access to physical activity and recreational facilities and may be one component of our national efforts to positively impact population health with respect to increasing physical activity. Reichert et al found that lack of money and lack of time were major barriers to physical activity.¹⁵ Because obesity is particularly prevalent in low-income communities the local built environment may be an important component of programs to increase physical activity among low-income communities.¹⁶

Our calculations include several limitations. Not all subway stations include an escalator and not all riders use the escalator. Many riders may have physical limitations that require use of an escalator or elevator. However, our intent is not to precisely measure the energy expenditure related to walking stairs. Rather, our intent is to point out the impact the built environment may have on our usual daily activities.

It is important to consider the built environment to support increasing usual daily activities as a target for the increasing physical activity. In this study we show that even small, incremental changes in physical activity may have significant impact on populations and individuals.