def vo2max
      # First check the event log for a vo2max reporting event.
      @events.each do |e|
        return e.vo2max if e.event == 'vo2max'
      end
      # Then check the user_data entries for a metmax entry. METmax * 3.5
      # is same value as VO2max.
      @user_data.each do |u|
        return u.metmax * 3.5 if u.metmax
      end

      nil
    end
def vo2max
      # First check the event log for a vo2max reporting event.
      @events.each do |e|
        return e.vo2max if e.event == 'vo2max'
      end
      # Then check the user_data entries for a metmax entry. METmax * 3.5
      # is same value as VO2max.
      @user_data.each do |u|
        return u.metmax * 3.5 if u.metmax
      end

      nil
    end
Returns the computed VO2max value. This value is computed by the device
 based on multiple previous activities.