Background/Purpose:
One challenge for weight loss intervention programs is to accurately assess caloric expenditure. Waist-worn, piezoelectric pedometers are accurate for measuring steps, but much less accurate for assessing caloric expenditure (Crouter et al, 2003). Newly designed, wrist-worn triaxial accelerometers claim to accurately assess caloric expenditure. This study examined the accuracy of the Nike FuelBand (NFB) and the Fitbit Force (FBF) in assessing caloric expenditure during motor-driven treadmill walking and running in obese adults (M BMI= 35.43, SD= 3.22).
Method:
Nineteen participants (M age= 21.16 years, SD= 3.59) were tested on one day in three consecutive but separate sessions: 1) resting supine for 10 minutes, 2) walking on a treadmill at self-selected speed for 10 minutes, and 3) running on a treadmill at self-selected speed for 10 minutes. During treadmill sessions, participants wore a NFB and FBF on the non-dominant wrist. Estimated caloric expenditure from the NFB and FBF was recorded for the last five minutes of each testing session. Metabolic data was measured using a TrueOne 2400 Metabolic Measurement System and energy expenditure in kcals was calculated based on the amount of oxygen consumed during the last five minutes of steady-state walking and running.
Analysis/Results:
The mean self-selected speed was 80.36 m/min (SD= 5.33) for walking and 136.21 m/min (SD= 26.11) for running.
Correlation coefficients between actual and estimated caloric expenditure for walking were -0.11 (NFB) and 0.28 (FBF); and for running were 0.64 (NFB) and 0.62 (FBF).
A repeated measures ANOVA determined caloric expenditure while walking differed significantly (F(2, 36)= 4.08, p= .025). Post hoc tests using Bonferroni correction revealed that actual caloric expenditure did not differ significantly (p= 1.0) from estimated caloric expenditure for the NFB (31.84 ± 14.51 vs. 32.0 ± 9.92) but did differ significantly (p= .048) for the FBF (31.84 ± 14.51 vs. 41.32 ± 10.99).
A repeated measures ANOVA determined caloric expenditure while running did not differ significantly (F(2, 36)= .018, p= .982). Post hoc tests using the Bonferroni correction revealed that actual caloric expenditure did not differ significantly from estimated caloric expenditure for either the NFB (73.53 ± 16.87 vs. 73.42 ± 12.65) or the FBF (73.53 ± 16.87 vs. 73.00 ± 10.66).
Conclusions:
Both the NFB and FBF accurately assessed caloric expenditure in obese adults during the running session. The results lend support to findings (Dondzila et al, 2012; Swartz et al, 2009) in which speed of locomotion was an impactful variable.