I was working out on my treadmill yesterday and usually try to vary the speed,intensity etc... well anyway I did 7mph at a 1%incline for 5straight minutes,then 8mph for 2 min, and then 9mph for 1 minute. I was surprised I was able to do that considering at 7mph made a 8:30pace per mile,9mph made 71/2pace per mile and 9mph made a 61/2pace per minute. too bad I cant do this outdoors and maintain that for my 5k races. I also jumped rope 5minutes 2x. That burns alot of calories in 10minutes according to sparkpeople.com. Anyway I think my endurance is finally getting better.I hope it continues to do so.