I did about 10 weeks of air alert and it did increase my vert a good 3-4 inches in that time, but it is extrememly hard on your body. The way air alert is set up you increase reps, not weight, and you never change excercises. The excercises are hard enough on your body with the low reps in the first week. By the time I hit week 10 the reps had gone up a ton and the excercises weren't any easier on my body. Anyways, it helps some but I'd be careful, I stopped because my knees were starting to bother me as well as my back. Weights are a good way to go unless you are naturally really strong with squats and stuff. I've seen just as much improvement (maybe more) from doing squats, leg curls, and calf raises as I did with air alert, and it isn't damaging my body.