PROJECTS
Physical Activity
What do your daily physical activity patterns say about your physical and cognitive health? We currently have two NIA-funded awards to better understand the links between physical activity, as measured using wearable technology, and cognitive health in older adults.
Energy Expenditure
Energy is expended at various intensities - from resting to maximal exertion - throughout the day, and the way we utilize energy changes dramatically with aging. We are investigating the intersection of energy expenditure and fatigability with aging and its effects on physical and cognitive functioning.
Accelerometry
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
Physical patterns and cognitive diagnosis
We demonstrate differences in the timing and patterns of physical activity throughout the day that are linked to MCI/AD diagnoses
"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
Physical activity volumes and patterns linked with brain volumes
Lower brain volumes in mid-to-late life are linked with lower amounts of daily physical activity and more fragmented patterns 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
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
Fatigability, Fatigue, and Mortality
Fatigue is an established prognostic indicator of mortality risk. This paper explored whether fatigability anchored to a physical task is a more sensitive than traditional measures of fatigue and whether sensitivity differs by prevalent chronic conditions.
Higher Energetic Cost of Walking Linked with Greater Brain Atrophy
This study examined the cross-sectional and longitudinal associations of the energetic cost of walking with brain volume in cognitively unimpaired adults from the Baltimore Longitudinal Study of Aging.
"Inflammaging" linked with fatigability
We demonstrated that elevated IL-6, a hallmark of "inflammaging," is a biomarker of physiological dysregulation associated with greater fatigability
Walking Energetics and Beta Amyloid Status
Adverse brain pathology is a known risk factor for Alzheimer's disease and related dementias. We investigated the cross-sectional association between the energetic cost of walking, gait speed, and amyloid beta (Aβ) status (+/-) in older adults.
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
Published research on accelerometry methods
Counts, MIMS, MAD or AI? What's the difference?
This study examined and compared summary measures of accelerometry-based physical activity data.
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
Validation of accelerometer placement to capture energy expenditure using doubly labeled water
This study compared accelerometer-measured physical activity by body placement to daily total energy expenditure (TEE) and activity energy expenditure (AEE) measured using doubly labeled water (DLW)
Comparing sleep parameters from Actigraph and Actiwatch
ActiGraph and the Actiwatch provide comparable absolute and relative estimates of total sleep time, but not other parameters. The discrepancies could result from device differences in movement collection and/or sleep scoring algorithms.
A Review of Wrist Accelerometry
Wrist-worn accelerometers have become especially popular because of low participant burden. However, the validity and reliability of wrist-worn devices for adults have yet to be summarized. This paper summarizes what is known about wrist accelerometry use in adult study populations.
Accelerating accelerometry research in older adults
This invited commentary discusses opportunities and challenges for future accelerometry research in 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