Fitbits and other wearable fitness monitors often provide values for VO2max (“cardio fitness score” in the Fitbit app), a measure of how well the body transports and uses oxygen to produce energy needed for physical activity. Strong relationships exist between VO2max and the risks of cardiovascular disease, some cancers and even death.
Thus, the American Heart Association has recommended that it be regularly assessed as a clinical vital sign and used for personalized exercise prescription. Given that its measurement is time consuming and requires costly specialized equipment, accurately estimating VO2max at home with a relatively inexpensive wearable would allow more people to determine their cardiorespiratory fitness.
Investigators in this study had 60 adults, aged 18 to 45 years, wear a Fitbit Charge 2 for one week while completing at least three 15-minute runs on flat terrain and compared the resulting VO2max estimate to the value obtained from a lab VO2max test on a treadmill. The Fitbit predicted VO2max with less than 10% error, suggesting that wearable devices can provide relatively accurate estimates of cardiorespiratory fitness in people who can run longer than 10 minutes on flat terrain. Read the article