Physical Activity

What does your daily physical activity pattern say about your physical and cognitive health? We currently have two NIA-funded awards to better understand the links among physical activity , physical function, and cognitive health in older adults. Through collaborations with NIA investigators, we are seeking to understand how quantities and patterns of movement are associated with brain pathology in the Baltimore Longitudinal Study of Aging.


Energy Expenditure

Energy expenditure is about more than just fitness!  Energy is utilized at various levels of intensity - from resting to maximal exertion - throughout the day, and the way we utilize energy changes dramatically with aging. We are currently investigating the intersection of energy expenditure and fatigability with aging and its effects on physical and cognitive functioning with aging.



We oversee the data collection, processing, and analysis of accelerometry data in multiple studies, including: ACHIEVE, ARIC, BLSA, MACS, NHATS, PASOS/SOL, SPRING, and STURDY.

Published research on physical activity patterns


"Assessing the Physical Cliff"

One of our first papers detailing age related differences in physical activity quantities and patterns

Fragmented physical activity linked with mortality

We demonstrated that fragmented physical activity patterns in older adults are more predictive of mortality than total volume of daily activity

Fragmented physical activity linked with low physical functioning

We demonstrated that a simple fragmentation index was strongly linked with physical performance in older adults, suggesting it is a signal of physiological decline

Older cancer survivors demonstrated reduced and more fragmented daily physical activity

Older cancer survivors demonstrated lower and more fragmented levels of physical activity throughout the day compared to those with no history of cancer

Defining activity intensity thresholds for older adults

Relative exertion of physical activity varies widely among older adults. We demonstrated that "one size does not fit all" for defining physical activity intensity by examining minute-level heart rate response to daily activities

High fatigability alters physical activity patterns

We showed that high fatigability contributes to reduced daily physical activity and altered diurnal patterns in older adults

Published research on Energy Expenditure & Fatigability


The Energetic Pathway to Mobility Loss

Our first energetics paper, which provided a conceptual framework of how energy expenditure affects mobility with aging

Higher fatigability linked with body composition

Our analysis examined the underlying contribution of body composition to fatigability in older adults across multiple measures. Greater body fatness, especially visceral fat was linked with higher fatigability in older adults.

"Inflammaging" linked with fatigability

We demonstrated that elevated IL-6, a hallmark of "inflammaging," is a biomarker of physiological dysregulation associated with greater fatigability

Fatigability & Endurance Peformance Among Cancer Survivors

Our research found that a history of cancer was associated with greater fatigability and poor endurance performance in older adults, even among long-term survivors

Rising Energy Costs Linked with Gait Speed Decline

We demonstrated a direct link between energetic efficiency and physical functioning by linking a higher energetic cost of usual-paced walking with gait speed decline in late life

Lower Resting Metabolic Rate Linked with Healthier Aging

Older well functioning adults who were free of major medical conditions had lower RMR than those with disease and functional impairments, suggesting a direct link between efficiency of energy utilization and health status.

published research on accelerometry methods


Monitors, Measures & Methods

This review article discusses the use of wearable accelerometers in older adults, and highlights methodological considerations in their application to older populations

Age related bias in step measurement

This letter to the editors of JAMA Internal Medicine highlights how slower speed of movement and altered biomechanics may lead to an age-related bias in the measurement of daily step counts

"ADEPT," a method to detect walking from accelerometry data

This work introduces the concept of "ADEPT" a pattern recognition method to detect walking from accelerometry data. Application of this methodology will allow future studies to compare in-lab measure of gait with free-living measures of ambulation.

Using raw accelerometry data for research

In this paper, we discuss problems related to the collection and analysis of raw accelerometry data and refer to published solutions. In particular, we describe the size and complexity of the data, the within- and between-subject variability, and the effects of sensor location on the body. We also discuss challenges related to sampling frequency, device calibration, data labeling and multiple PA monitors synchronization. 

Accelerating accelerometry research in older adults

This invited commentary discusses opportunities and challenges for future accelerometry research in older populations

Understanding gait characteristic from raw accelerometry data

This research highlights differences between walking measured "in-the-lab" and using accelerometers. Features of accelerometry-derived walking were associated with measures of physical function, mobility, fatigability, and fitness.