Our purpose in this study was to document the criterion validity of the Fitbit Zip for measuring steps taken by youth with visual impairments (VI). A secondary purpose was to determine whether walking pace, mounting position, or relative position to the user’s mobility device impacted the criterion validity of the device. Fourteen adolescent-aged individuals (M age = 15.4; 13 male and 1 female) with VI participated in this study. Participants wore four Fitbit Zips at different mounting positions and completed two, 2-min walking trials while the lead investigator hand tallied steps. Measurement validity was analyzed using absolute percent error (APE), intraclass correlation coefficients estimated level of conformity, and paired samples t tests and Cohen’s d effect sizes assessed APE relative to mounting positions. Results supported the use of the Fitbit Zip during regular-paced walking; however, caution must be used during activities exceeding regular walking speeds, as devices consistently underestimated steps.
Justin A. Haegele, Ali S. Brian and Donna Wolf
Stacy A. Clemes, Sarah L. Hamilton and Paula L. Griffiths
This study investigated whether pedometer-determined activity varies between summer and winter in normal-weight and overweight adults.
Forty-five normal-weight (58% female, age = 39.1 ± 12.4 years, BMI = 22.2 ± 2.1 kg/m2) and 51 overweight (49% female, age = 42.1 ± 12.5 years, BMI = 29.3 ± 4.5 kg/m2) participants completed a within-subject biseasonal pedometer study. All participants completed 2 4-week monitoring periods; 1 period in the summer and 1 period the following winter. Changes in step counts across seasons were calculated and compared for the 2 BMI groups.
Both BMI groups reported significant summer to winter reductions in step counts, with the magnitude of change being significantly greater in the normal-weight group (−1737 ± 2201 versus −781 ± 1673 steps/day, P = .02). Winter step counts did not differ significantly between the 2 groups (9250 ± 2845 versus 8974 ± 2709 steps/day, P = .63), whereas the normal-weight group reported a significantly higher mean daily step count in the summer (10986 ± 2858 versus 9755 ± 2874 steps/day, P = .04).
Both normal-weight and overweight individuals experienced a reduction in step counts between summer and winter; however, normal-weight individuals appear more susceptible to winter decreases in ambulatory activity, with the greatest seasonal change occurring on Sundays. Effective physical activity policies should be seasonally tailored to provide opportunities to encourage individuals to be more active during the winter, particularly on weekends.
Xihe Zhu and Justin A. Haegele
.1123/apaq.30.2.127 Clemes , S. A. , Matchett , N. , & Wane , S. L. ( 2008 ). Reactivity: An issue for short-term pedometer studies? British Journal of Sports Medicine, 42 ( 1 ), 68 – 70 . PubMed ID: 18178685 doi:10.1136/bjsm.2007.038521 10.1136/bjsm.2007.038521 Dössegger , A. , Ruch , N
Miguel Ángel de la Cámara, Sara Higueras-Fresnillo, David Martinez-Gomez and Óscar L. Veiga
.A. , Matchett , N. , & Wane , S.L. ( 2007 ). Reactivity: An issue for short-term pedometer studies? British Journal of Sports Medicine, 42 ( 1 ), 68 – 70 . doi:10.1136/bjsm.2007.038521 10.1136/bjsm.2007.038521 Cust , A.E. , Smith , B.J. , Chau , J. , van der Ploeg , H.P. , Friedenreich , C