FIRSTLY, I don't claim to really know what I'm talking about here, I am not a professional athlete or trainer by any means. I am simply sharing what I've learned from experience!
The fantastic woman who teaches the spin class I go to is a true athlete. She is the fittest and fastest cyclist. Unlike some spin class instructors she actually races with a team outside of the gym so she really knows her stuff. She had us doing these bursts and claimed it helps increase our VO2 max. Through laboured breathing and heavy sweating nobody asked what the heck she was talking about. Naturally I did some research into the type of training we were doing and what exactly VO2 max is.
Essentially it means "maximum oxygen uptake" The point where oxygen consumption plateaus. This definition is direct from good ol' Wikipedia: VO2 max is the maximum capacity of an individuals body to transport and use oxygen during incremental exercise, which reflects the physical fitness of the individual. VO2 max is reached when oxygen consumption remains at steady state despite an increase in workload.
Basically it is the determination of how efficient your lungs are.
The best way to increase your VO2 max is by interval training. In spin class she would have us gradually increase until we were at our maximum capacity and hold it there for a short 2 or 3 minutes with a 2 minute recovery in between before starting it again. We did this for the entire duration of the class. After researching it a bit more I began to understand the value of interval training for running or cycling. I am lucky to live near the escarpment in Hamilton and right near my house is a set of 330 stairs. When I was climbing the stairs once a week my running improved 10-fold! I found myself running faster and longer and with less effort. The stairs take about 4 minutes up and 3 minutes down. The first 2 minutes up my heart rate slowly increases and the second 2 minutes up I'm at peak capacity then a 3 minute recovery all the way back down. I do about 8-10reps of the stairs at a time. It can be a bit monotonous and time consuming, 10 reps last night took me 70 minutes. The nice thing about it is that its free, close to home and with lovely scenery. The picture doesn't do it justice, I took it half way up.
I find it benefits my blood sugar a lot also because its fairly constant exercise. Its demanding though and requires a very tiny temp basal. I enjoy it because I don't have to haul everything with me. I leave my glucose tabs, water and meter at the bottom and check every 2 or 3 reps. It is also good when I'm not feeling very ambitious to go far as I keep returning to the same spot. If I feel pooped or my BG isn't cooperating I'm not stuck with a 5km walk. Everytime I do the stairs I value where I live and that I have this great resource at my disposal anytime I like.
Anyway, it has benefited my performance greatly. I just wanted to share what I learned with anybody who is interested in the value of interval training!