1 minute walk/run intervals f/1hr ok?

Question
Hi. I just started running (more like jogging) again after several years' absence. I'm 38, maybe 130 pds, sort of ok shape but figure I could improve cardio, etc. I did a running room program a few years ago, 2 10k, one 5 k, used to do a lot of cycling. But the most I've done this past year is walk to and from work every day, about 45-50 minutes each way, plus cycling in the summer. I started jogging again recently with a 1-minute walk, 1-minute jog cycle. For about an hour. Don't know where I got the idea, but anyway, is there any validity/worth to this type of interval, or should I stick to the 4 minute walk work up to 4 minute jog cycle (as you suggested to another questioner)? I generally feel ok with it, and figured I'd work up to 1 minute walk, 2 minute jog, eventually jog/run for 20, then 30 minutes, and just see where I go with that. I also do about 20 minutes of stretching afterward. That said, I also feel I will probably cross-train and maybe switch it up with swimming once a wk and/or cycle, when the weather gets nicer. Thanks.
Caroline

Answer
You can increase your walk/run times for intervals. I think 20-30 minutes is about all you really need for a quality interval workout.  Intervals aren't supposed to be done over long periods of time, the point of them is to do more work in less time, hence, the shorter durations of those workouts.  

Rick Karboviak