Good news! You're likely burning more calories than you thought when you're walking

March 15, 2016 by Margaret Allen, Southern Methodist University
Jennifer Nollkamper and Dr. Lindsay Ludlow assist Dr. Takeshi Fujii in a treadmill test that captures volume of oxygen, volume of expired air and the levels of oxygen and carbon dioxide, all variables that help measure energy expenditure during walking. Credit: Hillsman Jackson, SMU

Walking is the most common exercise, and many walkers like to count how many calories are burned.

Little known, however, is that the leading standardized equations used to predict or estimate walking —the number of burned—assume that one size fits all. The equations have been in place for close to half a century and were based on data from a limited number of people.

A new study at Southern Methodist University, Dallas, found that under firm, level ground conditions, the leading standards are relatively inaccurate and have significant bias. The standards predicted too few calories burned in 97 percent of the cases researchers examined, said SMU physiologist Lindsay Ludlow.

A new standardized equation developed by SMU scientists is about four times more accurate for adults and kids together, and about two to three times more accurate for adults only, Ludlow said.

"Our new equation is formulated to apply regardless of the height, weight and speed of the walker," said Ludlow, a researcher in the SMU Locomotor Performance Laboratory of biomechanics expert Peter Weyand. "And it's appreciably more accurate."

Ludlow and her colleagues report the new equation in the Journal of Applied Physiology, "Energy expenditure during level human walking: seeking a simple and accurate predictive solution." The article is published in the March 1, 2016 issue, and available online at this link.

"The economy of level walking is a lot like shipping packages – there is an economy of scale," said Weyand, a co-author on the paper. "Big people get better gas mileage when fuel economy is expressed on a per-pound basis."

The SMU equation predicts the calories burned as a person walks on a firm, level surface. Ongoing research is expanding the algorithm to predict the calories burned while walking up- and downhill, and while carrying loads, Ludlow said.

SMU's research is funded by the U.S. Department of Defense Medical Research and Materiel Command. The grant is part of a larger DOD effort to develop load-carriage decision-aid tools to assist foot soldiers.

The research comes at a time when greater accuracy combined with mobile technology, such as wearable sensors like Fitbit, is increasingly being used in real time to monitor the body's status. The researchers note that some devices use the old standardized equations, while others use a different method to estimate the calories burned.

New equation considers different-sized people

To provide a comprehensive test of the leading standards, SMU researchers compiled a database using the extensive walking metabolism data available in the existing scientific literature to evaluate the leading equations for walking on level ground.

"The SMU approach improves upon the existing standards by including different-sized individuals and drawing on a larger database for equation formulation," Weyand said.

The new equation achieves greater accuracy by better incorporating the influence of body size, and by specifically incorporating the influence of height on gait mechanics. Specifically:

  • Bigger people burn fewer calories on a per pound basis of their body weight to walk at a given speed or to cover a fixed distance;
  • The older standardized equations don't account for size differences well, assuming roughly that one size fits all.

Accuracy of standardized equations had not previously undergone comprehensive evaluation

The exact dates are a bit murky, but the leading standardized equations, known by their shorthand as the "ACSM" and "Pandolf" equations, were developed about 40 years ago for the American College of Sports Medicine and for the military, Ludlow said.

The Pandolf method, for example, draws on walking metabolism data from six U.S. soldiers, she said. Both the Pandolf and ACSM equations were developed on a small number of adult males of average height.

The new more accurate equation will prove useful. Predicting energy expenditure is common in many fields, including those focused on health, weight loss, exercise, military and defense, and professional and amateur physical training.

"Burning calories is of major importance to health, fitness and the body's physiological status," Weyand said. "But it hasn't been really clear just how accurate the existing standards are under level conditions because previous assessments by other researchers were more limited in scope."

Energy expenditure estimates could assist with monitoring the body's physiological status

Accurate estimations of the rate at which calories are burned could potentially help predict a person's aerobic power and likelihood for executing a task, such as training for an athletic competition or carrying out a military objective.

In general, the new metabolic estimates can be combined with other physiological signals such as body heat, core temperature and heart rate to improve predictions of fatigue, overheating, dehydration, the aerobic power available, and whether a person can sustain a given intensity of exercise.

Military seeks solutions to overburdened soldier problem

The military has a major interest in more accurate techniques to help address their problem of over-burdened soldiers.

"These soldiers carry incredible loads—up to 150 pounds, but they often need to be mobile to successfully carry out their missions," said Weyand, a professor of Applied Physiology and Wellness in the SMU Simmons School of Education.

Accurately predicting how many calories a person expends while walking could supply information that can help soldiers avoid thermal stress and fatigue in the field, especially troops deployed to challenging environments.

"Soldiers incur a variety of physiological and musculoskeletal stresses in the field," Weyand said. "Our metabolic modeling work is part of a broader effort to provide the Department of Defense with quantitative tools to help soldiers."

Explore further: New equation calculates cost of walking for first time

More information: Lindsay W. Ludlow et al. Energy expenditure during level human walking: seeking a simple and accurate predictive solution, Journal of Applied Physiology (2016). DOI: 10.1152/japplphysiol.00864.2015

Related Stories

New equation calculates cost of walking for first time

November 12, 2010
Why do tall people burn less energy per kilogram when walking than shorter ones do, and how much energy does walking require? These are basic questions that doctors, trainers, fitness buffs and weight-watchers would all like ...

New study shows that varying walking pace burns more calories

October 8, 2015
Looking for a simple way to burn more calories while walking? Change up your pace.

Why you won't lose weight with exercise alone

January 28, 2016
Exercise by itself isn't always enough to take off the weight. Now, evidence reported in the Cell Press journal Current Biology on January 28 helps to explain why that is: our bodies adapt to higher activity levels, so that ...

'Hot' yoga yields fitness benefits according to researcher

July 14, 2014
Researchers at Colorado State University have produced some of the first scientific evidence that Bikram yoga, a type of "hot yoga," has beneficial effects on fitness.

Walking in place during commercials offers a good calorie burn

January 24, 2012
Fitness experts are always telling us that incorporating movement into our day is a good way to burn calories. But is it effective? A study finds that walking in place during commercials while watching TV actually provides ...

Army study improves ability to predict drinking water needs

July 8, 2009
When soldiers leave base for a 3-day mission, how much water should they bring? Military planners and others have long wrestled with that question, but new research from the Journal of Applied Physiology may now provide them ...

Recommended for you

A low-gluten, high-fiber diet may be healthier than gluten-free

November 16, 2018
When healthy people eat a low-gluten and fibre-rich diet compared with a high-gluten diet, they experience less intestinal discomfort including less bloating. Researchers at University of Copenhagen show that this is due ...

Youth dating violence shaped by parents' conflict-handling views, study finds

November 16, 2018
Parents who talk to their children about nonviolent ways of resolving conflict may reduce children's likelihood of physically or psychologically abusing their dating partners later—even when parents give contradictory messages ...

Why we shouldn't like coffee, but we do

November 15, 2018
Why do we like the bitter taste of coffee? Bitterness evolved as a natural warning system to protect the body from harmful substances. By evolutionary logic, we should want to spit it out.

Dietary fat is good? Dietary fat is bad? Coming to consensus

November 15, 2018
Which is better, a low-fat/high-carbohydrate diet or a high-fat/low-carbohydrate diet—or is it the type of fat that matters? In a new paper featured on the cover of Science magazine's special issue on nutrition, researchers ...

Low-carb diets cause people to burn more calories

November 14, 2018
Most people regain the weight they lose from dieting within one or two years, in part because the body adapts by slowing metabolism and burning fewer calories. A meticulous study led by Boston Children's Hospital, in partnership ...

Colder, darker climates increase alcohol consumption and liver disease

November 14, 2018
Where you live could influence how much you drink. According to new research from the University of Pittsburgh Division of Gastroenterology, people living in colder regions with less sunlight drink more alcohol than their ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.