just completed a few miles jogging on the treadmill. It was after doing the ab crunches that the light headedness happened. Age has a little to do with it I'm sure but didn't eat breakfast or lunch except for one of those nutrition bars. Over the years I have occassionally experienced this but this experience was on the fringe of passing out. Another was while doing DIPS. It seems to happen with non cardio exercises.(hasen't happened when inverted- such as PLLP) I'm not trying to talk myself out of them since I think the weight training is extremely important.