Why can't I run??? I just did the comprehensive fitness test at my gym. According to them I have a 54 VO2 Max, my sitting heart rate is 55bpm, which they say is pretty darn good for a 24 your old male. I weigh 197 with approx. 14.5% BF. Now, the problem is that back in the day, I could run 3m in under 21 minutes. My PR was 20:20, and at the time I was 205lbs. Now, even though my cardiovascular health is pretty good, I'd be lucky to run 3m in 27 min. What could be my limiting factor here? Flexibility? maybe leg strength? This is getting kinda frustrating, so any advice would be greatly appreciated.