Hi, I'm also a paitent of Dr. P. I've had 2 VO2 Max tests... Both were low. The first was 17% and the second was 19%. It was explained to me (whether I fully understand it is the question) that it was a form of mitochondrial myopathy-or lack of metabolizing oxygen as we can all relate. I was also not able to reach my max heart rate either time. My lung compacity was there, but the rest of my body failed. I recognize the burn feelings in my legs from my more fit days...The lactic acid burn. I also find it interesting that with my second test (both tests he also had my NK cells checked), and although I was 'feeling better' than the first test and my VO2 went up, my NK lytic activity was decreased.) I know they can vary quite a bit, but I still thought it was interesting Yes, I agree that deconditioning is a factor, and he also agreed when I asked that very question. But, I don't think it accounts for the amount that puts us in this category. I've never had a VO2 done a day or two after the initial test, but I can guarantee you my results would be much lower. There is definitely a crash and burn cycle. What has really helped me is to know my anaerobic threshold. By knowing this, I am able to watch my heart rate so that I don't enter the aerobic stage and reduce my flares and crashes.