PLEASE NOTE: THIS COLLECTION OF HUMAN HEART RATE AND GAIT DATABASES
WAS CONSTRUCTED AS A TEACHING RESOURCE FOR THE NECSI INTENSIVE COURSE
(OCTOBER 1999): "THE MODERN SCIENCE OF HUMAN AGING"
(www.necsi.org). AS SUCH, THIS SPECIFIC "MINI-COLLECTION" IS NOT
INTENDED FOR BASIC RESEARCH/PUBLICATIONS. HOWEVER, IT MAY BE USEFUL IN
OTHER CLASSROOM OR TUTORIAL SETTINGS, AND FOR SELF-GUIDED EXPLORATIONS
INTO THE WORLD OF BIOLOGIC COMPLEXITY. FOR CURRENTLY AVAILABLE
RESEARCH DATABASES, PLEASE CONSULT THE WEBSITE OF THE RESEARCH
RESOURCE FOR COMPLEX PHYSIOLOGIC SIGNALS (www.physionet.org).

Walking stride interval time series included are from 15 subjects: 5
healthy young adults (23 - 29 yrs old), 5 healthy old adults (71 - 77
yrs old), and 5 older adults (60 to 77 yrs old) with Parkinson's
disease. The file name indicates old (o), young (y) or Parkinson's
disease (pd). For the old and young subjects, the age (years) is also
included in the filename.

For each subject, two columns of data are included. The first column
is time (in seconds) and the second is the stride interval aka the
stride time aka gait cycle duration aka  the time between successive
heel strikes of the same foot. 

Subjects walked continuously on level ground around an obstacle free,
path and the stride interval was measured using ultra-thin, force
sensitive resistors placed inside the shoe.  The analog force signal
was sampled at 300 Hz, converted to a digital signal using 12 bit A/D
converter using an ambulatory, ankle-worn micro-computer that also
recorded the data.  Subsequently, the time between foot-strikes was
automatically computed. The method for determining the stride interval
is a modification of a previously validated method that has been shown
to agree with force-platform measures, ``gold'' standard.

Data from the healthy subjects collected as subjects walked in roughly
circular path for 15 minutes. Data from the subjects with Parkinson's
disease collected as subjects walked for 6 minutes up and down a long
hallway.

For additional information, please see www.physionet.org.
The following references may also be of interest:

JM Hausdorff, PL Purdon, CK Peng, Z Ladin, JY Wei,
AL Goldberger. Fractal dynamics of human gait: stability of
long-range correlations in stride interval fluctuations.
J Appl Physiol 80:1448-1457, 1996.

JM Hausdorff, SL Mitchell, R Firtion, CK. Peng, ME Cudkowicz, JY Wei
and AL Goldberger.  Altered fractal dynamics of gait: reduced stride
interval correlations  with aging and Huntington's disease.
J Appl Physiol 82:262-269, 1997.

JM Hausdorff, ME Cudkowicz, R Firtion, JY Wei, AL Goldberger.  Gait
variability and basal ganglia disorders: stride-to-stride variations
of gait cycle timing in Parkinson's and Huntington's disease. Mov
Disord 13:428-437, 1998.