KU Medical Center researcher co-leads development of 2024 Compendium of Physical Activities

It’s a new year and for many people, that means trying to get more exercise. And after each two-hour hike, 10-mile bike ride or hour-long Pilates class, many of us will be consulting our trusty smartwatches and fitness-tracking apps to see how many calories we burned.

When we do, the numbers those devices give us likely will be based on data pulled from the Compendium of Physical Activities, a standardized resource for classifying and quantifying the energy expended for a wide variety of activities. The compendium includes not only activities we do for the purpose of exercise, but also such everyday activities as riding in the car, playing the piano, mowing the yard, attending a church service and laughing.

The first compendium, the development of which was overseen by Barbara Ainsworth, Ph.D., an exercise physiologist then at Arizona State University, was released in 1993. Updated versions were released in 2000 and 2011. The compendium is widely used around the world by researchers, health professionals and consumer-health technology companies. It has also been used to create guidelines for physical activity issued by the World Health Organization, the U.S. Department of Health and Human Services and other public health organizations.

On January 17, the 2024 Compendium of Physical Activities was released by an international group of researchers co-led by Steve Herrmann, Ph.D., research assistant professor in the Division of Physical Activity and Weight Management at the University of Kansas Medical Center. Herrmann had worked with Ainsworth on the 2011 update to the compendium when he was earning his doctorate at Arizona State.

“The Compendium of Physical Activities has long been a cornerstone resource for measuring physical-activity intensity levels and understanding their health implications,” said Herrmann. “The 2024 update reaffirms our commitment to providing the most current and practical information for effective physical activity assessment.”

The compendium was originally developed to standardize the way energy expenditures were measured in research studies looking at the association between physical activity and health, particularly for people with cardiovascular disease. At the time, there were numerous physical activity assessment tools used across studies, and they used different metrics. “The idea was that we needed to consolidate and use one consistent metric so we could do better at comparing,” said Herrmann, who co-led the project with Erik Willis, Ph.D., a research scientist at the University of North Carolina Center for Health Promotion and Disease Prevention, and Scott Conger, Ph.D., an exercise physiologist at Boise State University.

That standard metric is a MET, which stands for metabolic equivalent of task. One MET equates to the amount of energy the average person burns while resting. Calories expended can then be calculated from the number of METs for a given activity. To create the first version of the compendium, the researchers compiled a list of activities listed on physical-activity assessment questionnaires and converted the energy costs associated with them into METs. In the 2000 and 2011 updates, more activities were added, and the MET values were adjusted using additional available data.

The 2024 compendium includes more than 300 new activities and a new section on video games, as well as further refinements to the MET values. “We have so much data on walking and running, that now it’s not just walking at three miles an hour; now it's walking at three miles an hour uphill at a 5%, 10% or 15% incline, or walking downhill, or walking three miles an hour with a backpack weighing 12 pounds,” said Herrmann.

The researchers have also added a separate Compendium for Older Adults, which contains MET values adjusted according to the lower metabolic rate in people aged 60 and over. “This tailored addition acknowledges the distinct needs of older individuals, offering a valuable resource to enhance comprehension of activity intensity levels and their implications for health in this population,” said Willis, who led its development.

They have also updated a separate compendium for adult wheelchair users that contains adjusted MET values for activities specific to this population. “Providing a comprehensive list of activities for wheelchair users is an important step in promoting inclusive physical activity and recognizing the unique differences in metabolism and activities,” said Conger, who oversaw the update for the wheelchair compendium.

These additions and updates expand and improve the data that can be used by researchers and health professionals and be incorporated into fitness apps and wearable technology such as smartwatches.

The researchers are also talking about creating other separate compendia specific to different populations. “We are working with another group right now that's very interested in women during pregnancy and postpartum, and there also have been people asking about MET values for individuals with Down syndrome,” said Herrmann. “I think as we move into the future, there will probably be some additional, specific subgroups for whom we can collect and report data.”