VO2 max test

Last February I took a EKG stress test to get a baseline of my heart for future. It used the Bruce Protocol as part of the assesment, which extrapolated to a VO2 max number of 48.5.
Yesterday I went and took a proper VO2 max test at Bridgetown PT. The test consisted of running on treadmill with a mask and hose strapped to your face and a heart rate monitor. The test itself took ~15 minutes, starting at 4mph ramping up to 10mph. I ended up with a peak VO2 of 52.6 ml/kg/min.
Besides the VO2 number, I also got my Aerobic and Anaerobic numbers. My Anaerobic Threshold is only 157, so there is more work to be done.
Zone Low Moderate High Peak
HR 104-146 146-157 157-168 168-172
C/hr 245-943 943-1113 1113-1384 1384-1474