The machine could have been calibrated wrong. I had a test where I scored a 86 or something but in actuality it was more of a 79 . Its mmol O2/ KG of body mass I think, but I am probably wrong as I am NOT an exercise physiologist. It not really a good measure. Efficiency has more to do with your running. Also, I got a 58 on a bike test, I was fatter at that point of the test as well but still a lower score, because I was not trained as a cyclist. Also, the ski machine seems to favor a higher score more so than running I was told. I had comparable VO2 numbers to my teammates, but they were much more efficient and therefore much faster than me.