The accuracy of the FitSense FS-1 speedometer for estimating distance, speed, and energy expenditure

The purpose of this study was to examine the accuracy of the FitSense FS-1 Speedometer for estimating distance, speed, and energy expenditure while walking and running at different speeds and grades. The study was divided into three experiments. Experiment I investigated the accuracy of the FitSense for estimating distance while walking and running at self-selected speeds during repeated 1600 m tests. Experiment II investigated the accuracy of the FitSense for estimating speed (vs. a handheld digital tachometer) and energy expenditure (vs. indirect calorimetry) during treadmill walking (3.0, 4.0, and 5.0 miles • hr^-1) and running (5.0, 6.0, and 7.0 miles • hr^-1) on a level grade. Experiment III investigated the accuracy of the FitSense for estimating energy expenditure (vs. indirect calorimetry) during treadmill walking with an increasing grade (0.0, 2.5, 5.0, 7.5, and 10.0%). Twenty-four subjects (15 male, 9 female) volunteered for Experiment I. A subset of 12 subjects (7 male, 5 female) also volunteered for Experiments II and III. For Experiment I, one-sample t-tests revealed no significant difference between actual distance and the distance estimated by the FitSense during the walking tests. A significant difference was found for distance while running (p = 0.016). During Experiment II, a significant difference was found for speed while walking on a level grade. Post-hoc pairwise comparisons found significant stage differences between 3.0 and 5.0 miles • hr^-1 and 4.0 and 5.0 miles • hr^-1. Paired t-tests found no significant differences between the estimated and measured speed for walking speeds of 3.0 and 4.0 miles • hr^-1 or for running speeds of 5.0, 6.0, and 7.0 miles • hr^-1. A significant difference between measured and estimated speed was found while walking at 5.0 miles • hr^-1 (p < 0.001). A repeated measures ANOVA demonstrated significant differences for energy expenditure while walking on a level grade. Post-hoc pairwise comparisons revealed significant differences between each stage while walking. Paired t-tests also found significant differences between measured and estimated energy expenditure while walking at 4.0 and 5.0 miles • hr^{-1,/sup>. No significant differences were found for energy expenditure while running. In Experiment III, a significant difference was found for energy expenditure while walking with an increasing grade. Post-hoc pairwise comparisons revealed significant differences between each grade. Paired t-tests also found significant differences between measured and estimated energy expenditure for each grade. In conclusion, the FitSense FS-1 Speedometer is an accurate tool for estimating distance while walking and running and for estimating speed while walking at 3.0 and 4.0 miles • hr-1 and running at 6.0 and 7.0 miles • hr-1 on a level grade. However, the FitSense underestimates energy expenditure while walking and running on a level grade and with an increasing grade.}