Published on in Vol 7 , No 5 (2019) :May
Preprints (earlier versions) of this paper are
available at
https://preprints.jmir.org/preprint/13547, first published
.

1 Department of Kinesiology, University of Wisconsin - Madison, Madison, WI, United States
2 Department of Population Health Sciences, University of Wisconsin - Madison, Madison, WI, United States