VO2 max. is the maximum volume of oxygen (in milliliters) you can consume per minute per kilogram of body weight at your maximum performance. In simple terms, VO2 max. is an indication of athletic performance and should increase as your level of fitness improves. VO2 max. estimates are provided and supported by Firstbeat^® Technologies Ltd. You can use your Garmin^® device paired with a compatible heart rate monitor to display your running VO2 max. estimate.