Validity of energy expenditure for the Garmin Vivofit during a week of physical activity

Purpose To determine the accuracy of energy expenditure measured by the Garmin Vivofit during a 7 day period of daily living in comparison to a research grade accelerometer, Actigraph. Methods Participants wore a research grade accelerometer (Actigraph GT3X+) and a Garmin Vivofit device for 7 straight days, 24 hours a day. Paired t-tests were used to examine mean differences in 7-day mean energy expenditure and step values obtained between the devices, as well as the mean energy expenditure values for each day. Pearson correlation was used to assess the relationship of energy expenditure between the devices. Statistical significance was set a priori at p \u3c 0.05. Results There was no significant difference between the Actigraph and the Vivofit for mean total daily energy expenditure. The Vivofit reported a significantly lower mean daily active energy expenditure (271.13 vs 513.02 kcals, for Vivofit vs. Actigraph, respectively, p \u3c 0.001). The Vivofit reported significantly higher mean daily step averages (13,412.00 vs. 11,307.58, for Vivofit vs. Actigraph, respectively, p = 0.01). Paired t-test analysis of mean active kilocalories concluded a significance difference on all 7 days between the devices. There was no significant difference between the devices for mean total kilocalories for any day. Pearson correlations were highly significant between the devices for both total and active kilocalories (r = 0.99, p \u3c 0.001). Conclusion The Vivofit total energy expenditure results matched expected results of having no significant difference between the devices. Active energy expenditure and step results were unexpected with the Vivofit underestimating daily active energy expenditure and overestimating daily step averages as compared to the Actigraph. Keywords: Actigraph, Garmin Vivofit, energy expenditur