VALIDATION OF THE GARMIN FORERUNNER 265 TO ESTIMATE VO2MAX ANDPREDICT HALF-MARATHON RACE PERFORMANCE

PURPOSE: Advances in fitness tracker technology have led to increased measurements and predictions of physiological variables that allow devices to provide increasingly sophisticated information to users such as VO2max and race prediction times. These data can help develop personalized exercise programs and race strategies. Validity evidence of wrist based fitness trackers to estimate VO2max has been mixed due to changes in technology and heartrate measurements, and studies have not yet investigated race performance prediction. It was hypothesized that Garmin watches would provide valid estimates of VO2max and race prediction times with validity improving with 12 weeks of continuous use. METHODS: Twenty subjects participated in 12 weeks of half marathon training, wore a Garmin watch for the duration of the training program, and ran a half marathon race. Before the training program, subjects completed a VO2max test on a treadmill and two 10 minute outdoor runs while wearing a Garmin Forerunner 265. Upon completion of the training program, subjects competed in a half marathon and, 7-14 days later, completed a second VO2max test. Garmin watch estimates of VO2max and race performance predictions were compared to criterion measures using paired samples t-test and by calculating mean absolute percent error (MAPE). Significance was set at p < 0.05. RESULTS: The initial mean VO2max estimate from Garmin (43.95 ± 7.99 ml/kg/min) was significantly higher compared to the criterion max test (41.10 ± 8.02 ml/kg/min), t = 2.92 p = .009. After 12 weeks of training, estimated VO2max from Garmin (45 ± 7.21 ml/kg/min) was also significantly higher than the criterion (42.43 ± 8.54 ml/kg/min), t = 3.05 p = .007. Garmin's race prediction for the half marathon (129.97 ± 18.29 min) was significantly faster than the official race completion time (137.55 ± 21.03 min), t = -3.55 p = .003. Despite this, MAPE of VO2max and race prediction were below 10%, an acceptable threshold set by the Consumer Technology Association (CTA). CONCLUSION: The Garmin Forerunner 265 significantly overestimated VO2max after 1 exercise session and after 12 weeks of use. It also predicted a race time that was significantly faster than the actual race time. However, from a consumer perspective based on CTA standards, the device may be considered an adequate tool for runners. Supported by: Dr. David R Martin Research Fund supported this project