Jacek K. Erbanek

Multi-day remote measurements of physical activity, mobility, diurnal patterns, and sleep in community-dwelling older adults: Part 1 of a series on the Johns Hopkins Accelerometry Resource Core

Image of physical activity

Part One of a two part series on the important role of accelerometry in aging science. The Accelerometry Resource Core (ARC) at COAH has been created to help wearable data become one of the pillars of modern medicine and epidemiology by increasing its accessibility to a wide range of health researchers. To learn more about the ARC, visit accelerometry.org or reach out to Dr. Urbanek directly: jurbane2@jhu.edu or at wearables@jhu.edu.

In recent years, small wearable devices that collect various biological signals have experienced rapid growth in popularity in research and consumer use. Among the many types of wearable sensors, accelerometers that measure the movement of individuals throughout the day and over multiple days are likely the most common. Devices like Fitbit, Apple Watch, and research-oriented Actigraphs have been implemented in various large observational studies, clinical trials, and interventions. These devices are small, waterproof, non-invasive and, in their recent iteration, can be worn like a watch without the need for removing for sleep or bathing.

Accelerometers, while most commonly associated with workout tracking and step counting, are capable of much more. Advances in mobile technology over the last decade, have led to smaller sensors with increased memory capacity and battery life, and more affordable prices. As a result, modern, research-grade wearable accelerometers can now collect and store three-dimensional, high-frequency data on human movement continuously over multiple days and nights. For the first time, researchers can gain detailed insight into physical activity, mobility, diurnal rhythms, and sleep characteristics in the context of health.

image of Jacek Urbanek and diurnal pattern

Click here to watch a quick video with Dr. Jacek Urbanek demonstrating just one example of data that a wearable device can pick up from simply clapping his hands, and begin to imagine the bench to bedside possibilities that accelerometry can add to research, clinical trials, and patient centered care.

In the aging population, activities of daily living, mobility, and gait speed are often considered as key measures that can predict various health and quality of life outcomes including functional independence, sensory loss, physical frailty, falls, and death. Advances in wearable technology have not only expanded the ability to effectively monitor and improve the understanding of these measures, but also provide for the remote, multi-day collection of data in free-living conditions that are the most natural to the patient. This results in observations that go beyond the in-clinic snapshot and reflect a more accurate spectrum of movement across a variety of contexts. The importance of the remote collection of clinically relevant data has been further emphasized by the recent COVID-19 pandemic that caused significant limitations to in-person healthcare, especially affecting older, at-risk populations.

Wearable accelerometers were brought into the research spotlight by high-impact, large observational studies focused on general populations. The National Health and Nutrition Examination Survey (NHANES) introduced hip-worn devices in 2003 for the assessment of free-living physical activity and continued this measurement though 2006. Further, NHANES resumed the assessment in 2013 with a new generation of wrist-worn Actigraphs. Similarly, the Study of Latinos (SOL) successfully used wearable accelerometers to monitor longitudinal changes of physical activity across study visits, which is now followed by the assessment with the state-of-the-art devices implemented as a part of Peripheral Artery Disease Study of SOL (PASOS). Internationally, in 2013, the UK Biobank introduced a large-scale cross-sectional collection of wrist-worn accelerometry data to characterize physical activity in the population of the United Kingdom. That success motivated more focused observational studies, clinical trials, and interventions to collect data using wearable devices. In aging research studies, the Baltimore Longitudinal Study of Aging (BLSA) pioneered large-scale monitoring of free-living physical activity and sleep characteristics in older adults, shortly followed by the National Health and Aging Trends Study (NHATS). Overall, the multi-day observation of movements of individuals in real-world settings has been found useful in all areas of health research where physical activity, mobility, or sleep may play an important role. In addition to aging, these areas include frailty, cardiovascular health, recovery after a surgery or clinical stressor, weight loss interventions and obesity, HIV/AIDS, chronic kidney disease, and Alzheimer’s disease, among others.

While wearable devices have been successfully implemented in many existing and new research studies, the technology is still novel and rapidly evolving. The Accelerometry Resource Core (ARC) at the Johns Hopkins Center on Aging and Health has been created to help wearable data become one of the pillars of modern medicine’s clinical practice and research, including epidemiology, by increasing its accessibility to a wide range of health researchers. The ARC offers a full range of collaborative services and provides the expertise, tools, and human resources required for the successful implementation of these measurements. The core is currently collaborating with multiple large-, mid-, and small-size studies by overseeing the collection and providing analytical support for wearable data. Among the most recognizable collaborators are the NHATS, Atherosclerosis Risk in Communities (ARIC), Aging, Cognition and Hearing Evaluation in Elders (ACHIEVE), BLSA, Study To Understand Fall Reduction and Vitamin D in You (STURDY), Characterizing Resiliencies to Physical Stressors in Older Adults (SPRING), PASOS, and Chronic Kidney Disease in Children (CKiD). Throughout these collaborations, members of the ARC have collected, processed, and analyzed cross-sectional and longitudinal data from over 5,000 participants, including over 4,000 older individuals, effectively becoming the largest repository of harmonized, sub-second level, wrist accelerometry data in older adults in the United States.


Stay tuned for Part Two of this article, coming soon!

image of David L. Roth

Dr. David L. Roth to Receive the 2021 M. Powell Lawton Award from the Gerontological Society of America

Dr. David L. Roth, Professor of Medicine in the Division of Geriatric Medicine and Gerontology and Director of the Johns Hopkins Center on Aging and Health (COAH), will receive the M. Powell Lawton Award at the Gerontological Society of America (GSA) Annual Scientific Meeting, which will be held online this year from November 10th to 13th.  The award presentation will be on Saturday, November 13, 2021 starting at 4pm, and it will be followed by a lecture from last year’s recipient, Dr. Sara Czaja, who leads the Center on Aging and Behavioral Research at Weill Cornell Medicine; following GSA tradition, Dr. Roth will deliver the M. Powell Lawton lecture next year.  To register for the GSA’s virtual Annual Scientific Meeting, click here.

According to Google Scholar, Dr. Roth’s research has been cited over 22,000 times and he has the most citations of any scholar in the field of Applied Gerontology.  He has led a strong program of research on family caregiving and well-known for his 2015 paper, “Informal caregiving and its impact on health: A reappraisal from population-based studies.” These and other papers have gained increasing attention, including: an interview with Dr. Roth in The New York Times.

When asked about what this award means to him, Dr. Roth expressed gratitude for the GSA’s leadership in having such awards as a way to draw public attention to key global aging matters. “I think, with the population around the world getting older, understanding the special needs of older adults as well as their accumulated wisdom is very important. The GSA is leading the way in supporting and rewarding successful researchers who are investigating key questions in aging research. I’m grateful to GSA for having awards like the Lawton Award to promote research and scientific discoveries around the globe,” Dr. Roth said.

“Like all awards, this is really a reflection of the larger teams I have been so fortunate to be on over the years.  I am grateful to have had so many outstanding colleagues and truly honored to be selected for this award,” Dr. Roth stated upon hearing that he had won the award. Known for his collaborative nature and statistical expertise, Dr. Roth has developed a reputation for bringing excellence in methodology, elegance in statistics, and vision in creative and innovative ideas to his many collaborations. Notably, Dr. Roth has collaborated on many papers over time with Dr. William Haley at the University of Southern Florida, Dr. Virginia Howard at the University of Alabama at Birmingham, and Dr. Mary Mittelman at New York University. Additionally, he has joined numerous research teams with many colleagues at Johns Hopkins University.

As an investigator, Dr. Roth has contributed at least one meaningful, original, peer-reviewed, data-based research publication across a diverse range of topics every year for the past 37 consecutive years.  Here is a sampling of some of the influential and highly cited papers by him and his colleagues:

As COAH’s director since 2012, and as a senior faculty member in the Division of Geriatric Medicine and Gerontology, Dr. Roth supports a diverse group of scholars engaged in aging-related research and public service.  This includes mentoring and supporting numerous postdoctoral fellows and junior faculty members.   Dr. Roth is proud that COAH can provide a comprehensive resource for specialized research, training, and community engagement. “COAH is a voice in the community and our work is having an impact on the world,” he said. Personally, he has provided expertise to the local community through his membership on the Baltimore, and Maryland State, Commissions on Aging. Also, Dr. Roth has served on the Editorial Boards of top journals in gerontology, including Psychology and Aging, Journal of Gerontology: Psychological Sciences, and Journal of Aging and Health.

In an announcement to the Division of Geriatric Medicine and Gerontology, Director Dr. Cynthia Boyd noted that “Dr. Roth bridges methodological rigor with expertise in content and theory in highly interdisciplinary applied interventional research. Cumulatively, the impact of his work on improving the quality of life of older adults and their family caregivers has reached large numbers of older adults.”

The COAH family salute Dr. Roth upon this remarkable achievement. Congratulations!

The M. Powell Lawton Award, sponsored by Abramson Senior Care’s Polisher Research Institute, recognizes outstanding contributions from applied gerontological research that have benefited older people and their care. The award was established to honor the memory of the late M. Powell Lawton, PhD, director emeritus of the Polisher Research Institute and a leading figure in aging research.  Recipients exemplify Dr. Lawton’s personal and professional qualities, and their contributions in gerontology have led to innovations in gerontological treatment, practice or service, prevention, or amelioration of symptoms or barriers. Individuals who have influenced public policy changes or demonstrated leadership in defining and implementing a creative program that led to improvement in the lives of older persons are also eligible.


Jennifer Schrack, PhD

Congratulations to Dr. Jennifer Schrack of COAH, named as new Co-PI of NHATS!

Associate Professor of Epidemiology, Jennifer A. Schrack, PhD, MS, with the Johns Hopkins Bloomberg School of Public Health, recently ascended to a Co-PI leadership role with the  National Health and Aging Trends Study (NHATS), which systematically gathers information over time from a nationally representative sample of Medicare beneficiaries ages 65 and older.

Regarding this significant research role, Dr. Schrack said, “I look forward to continuing what has been done so well by NHATS for the past decade, and to looking for ways to expand and advance our understanding of disability in late life.”  Annual NHATS interviews with participants are critically important to collect insightful information about the physical, social, and economic well-being of older and differently abled adults, such as: the physical, social, technological and service environment; tests and self-reports of physical and cognitive capacity; use of assistive devices and rehabilitation services; help received with daily activities (self-care, household, and medical); and participation in valued activities. Additionally, participants’ family members may be interviewed about the quality of end of life care that was received by NHATS participants who have died. Dr. Schrack is well-qualified for NHATS leadership. Her primary research focuses on the role of physiological factors in maintaining mobility and preventing disability with aging. She directs the Epidemiology of Aging Track and co-leads the Accelerometry Research Core at the Johns Hopkins Center on Aging and Health.  With a Masters in Exercise Physiology from the University of Michigan and a PhD in Epidemiology from the Johns Hopkins Bloomberg School of Public Health, Dr. Schrack has extensive clinical research as an exercise physiologist, with an emphasis on the assessment physical function, energy expenditure, and physical activity using accelerometers.

In addition to previously being an investigator with NHATS, Dr. Schrack is the PI of a U01 from the NIA to delineate associations among energy regulation, physical activity, and Alzheimer’s disease, and the Co-PI of a R01 from the NIA to investigate sensory and motor contributions to the development of preclinical Alzheimer’s disease. In addition, she is a co-investigator of the Baltimore Longitudinal Study of Aging (BLSA), the Study of Physical Resiliency iN Geriatrics (SPRING), the Study to Understand vitamin D and falls in You (STURDY), the Aging, Cognition, and Hearing Evaluation in Elders (ACHIEVE) Randomized Trial, and the Atherosclerosis Risk in Communities (ARIC) study.  Dr. David Roth, the Director of the Center on Aging and Health at Johns Hopkins, lauded the selection of Dr. Schrack for her new leadership role in NHATS.  Dr. Roth noted that “Dr. Schrack is an extremely talented, committed, and influential scholar who also has outstanding organizational and supervisory skills.  She will do a great job in leading NHATS in collaboration with the other exceptional researchers working on that very important project.”

The Johns Hopkins University Bloomberg School of Public Health and the University of Michigan’s Institute for Social Research lead NHATS with support from the National Institute on Aging, with data collection via Westat. Dr. Vicki Freedman from the Institute for Social Research at the University of Michigan is NHAT’s senior co-PI; Dr. Schrack steps into this role following the death of her friend and Bloomberg School of Public Health colleague, Dr. Judith Kasper, the former NHATS Co-PI from Johns Hopkins, who deceased on August 5, 2021 from a heart attack at her home in Bolton Hill, Baltimore; you may read Dr. Kasper’s obituary here.