Assessing the ability of the Fitbit Charge 2 to accurately predict VO2max

• Published in: mHealth 2019-09, Vol.5, p.39-39
• Main Authors: Freeberg, Kaitlin A., Baughman, Brett R., Vickey, Ted, Sullivan, Jeff A., Sawyer, Brandon J.
• Format: Article
• Language: English
• Subjects: Original
• ISSN: 2306-9740; 2306-9740
• DOI: 10.21037/mhealth.2019.09.07

BACKGROUNDThe aim of this study was to assess the ability of the Fitbit Charge 2 (FBC2) to accurately estimate VO2max in comparison to both the gold standard VO2max test and a non-exercise VO2max prediction equation. METHODSThirty healthy subjects (17 men, 13 women) between the ages of 18 and 35 (age =21.7±3.1 years) were given a FBC2 to wear for seven days and followed instructions on how to obtain a cardio fitness score (CFS). VO2max was measured with an incremental test on the treadmill followed by a verification phase. VO2max was predicted via a non-exercise prediction model (N-Ex) using self-reported physical activity level. RESULTSMeasured VO2max was significantly lower than FBC2 predicted CFS (VO2max =49.91±6.83; CFS =52.53±8.43, P=0.03). N-Ex prediction was significantly lower than CFS but not significantly lower than measured VO2max (N-Ex =48.79±6.32; CFS vs. N-Ex: P=0.01; VO2max vs. N-Ex: P=0.54). Relationships between both VO2max vs. CFS and VO2max vs. N-Ex were good (ICC: VO2max vs. CFS=0.87, VO2max vs. N-Ex =0.87); Bland-Altman analysis indicated consistency of CFS measurement and lack of bias. The coefficient of variation (CV) and mean absolute percent error (MAPE) were greater with CFS than N-Ex (CV: CFS =6.5%±4.1%, N-Ex =5.6%±3.6%; MAPE: CFS =10.2%±6.7%, N-Ex =7.8%±5.0%). Heart rate (HR) estimated by the FBC2 was lower than estimated (Est) HR for pace based on HR extrapolation (FBC2 =155±18 bpm, Est =183±15 bpm, P