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Jennifer A. Schrack, PhD

  • Assistant Professor

Departmental Affiliations

  • Epidemiology (Primary)
    • Division: Epidemiology of Aging
  • Krieger School of Arts and Sciences (Joint)

Center & Institute Affiliations

Contact Information

615 N. Wolfe Street
Room E7144
Baltimore, Maryland 21205


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PhD, BSPH, 2011
MS, University of Michigan, 2002


Dr. Schrack's primary area of research is the epidemiological assessment of physical activity and its associations with health and longevity in older populations.

Physical activity is a modifiable risk factor for functional decline, disease development, and disability in older populations. The advent of accelerometers presents an unprecedented opportunity to better understand daily physical activity quantities, patterns, and trends, and the subsequent effects on health outcomes. These technologically advanced monitors have the potential to ultimately transform physical activity research and to be widely used as preventative therapy tools. 

In collaboration with the SMART group ( from the JHSPH department of biostatistics, Dr. Schrack is working to establish methods to analyze and translate heart rate and accelerometry data into accurate and reliable measures of physical activity in older populations.  This work is crucial to understanding changes in energy expenditure and physical function with age and for managing and treating chronic conditions in older adults.

Honors and Awards

2017 Johns Hopkins University Catalyst Award

2014 - 2017 K01 Career Development Award, National Institute on Aging

2014 - 2015 Johns Hopkins Roybal Center Faculty Pilot Award

2013 - 2015 Johns Hopkins Center for AIDS Research Faculty Development Award

2011 - 2012 National Institute on Aging Intramural Postdoctoral Fellowship

2007 – 2011 National Institute on Aging Epidemiology and Biostatistics of Aging Training Grant Fellow, Johns Hopkins Bloomberg School of Public Health

Selected publications

  • Schrack JA, Cooper R, Koster A, Shiroma EJ, Murabito JM, Rejeski WJ, Ferrucci L, Harris TB. Assessing Daily Physical Activity in Older Adults: Unraveling the Complexity of Monitors, Measures, and Methods. J Gerontol A Biol Sci Med Sci. 2016 Aug;71(8):1039-48. doi: 10.1093/gerona/glw026. Review.PMID: 26967472
  • Schrack JA, Zipunnikov V, Goldsmith AJ, Crainiceanu CM, Simonsick EM, Ferrucci L.  Assessing the “Physical Cliff”: Detailed Quantification of Physical Activity and Aging. J Gerontol A Biol Sci Med Sci. 2014 Aug;69(8):973-9. PMID: 24336819.
  • Schrack JA, Zipunnikov V, Crainiceanu C. Electronic devices and applications to track physical activity. JAMA. 2015 May 26;313(20):2079-80. PMID:26010643
  • Schrack JA, Zipunnikov V, Simonsick EM, Studenski S, Ferrucci L. Rising Energetic Cost of Walking Predicts Gait Speed Decline with Aging. J Gerontol A Biol Sci Med Sci. 2016 Jul;71(7):947-53. doi: 10.1093/gerona/glw002. PMID: 26850913
  • Schrack JA, Jacobson LP, Althoff KN, Erlandson KM, Jamieson BD, Koletar SL, Phair J, Brown TT, Margolick JB; for the Multicenter AIDS Cohort Study. Effect of HIV-infection and cumulative viral load on age-related decline in grip strength. AIDS. 2016 Nov 13;30(17):2645-2652. PMID: 27603294
  • Baltimore Longitudinal Study of Aging
  • MACS Energy Expenditure Study