Fitbit Activity Monitor Results Correlate with Subjects’ K-level


Researchers at the Rehabilitation Institute of Chicago (RIC), Illinois, used the Fitbit® One, a consumer-oriented activity monitor, to assess the mobility of people with transfemoral amputations. The results indicate that the amount of movement time a study participant spent above the "fairly active" level had a predictable relationship to his or her designated K-level. The study was published online on June 19 in PM&R, the journal of the American Academy of Physical Medicine and Rehabilitation.

Four women and five men between the ages of 21-64 with transfemoral amputations participated in the feasibility study. Seven were classified at a K3 functional level, one at K2, and one at K4. The researchers monitored each participant's physical activity using the Fitbit One for one week, tracking daily estimates of step counts, distance walked, floors/stairs climbed, calories burned, and proprietary Fitbit activity scores. For each day, the amount of time spent in sedentary, lightly active, fairly active, and highly active behaviors were also reported.

The researchers found decreased levels of activity for subjects with obesity, and that estimated step counts could predict estimated miles walked without setting individual stride lengths. Calorie estimates were found to be highly dependent on each participant's age, height, and weight, but that the proprietary activity score was independent of those factors. The researchers concluded that the Fitbit can estimate the activity level of people with transfemoral amputations and produce results that correlate with their K-level functional activity classifications. Consequently, this type of tool may provide information about a prosthetic user's activity level in his or her home setting.