Plyometrics, good or bad?

Based on what I've learned and seen I would use weight training before
plymometrics in my training. Studies by the University of Texas show only a slight increase in running economy using plyometrics training in a 6 week study by average distance runners. The study showed no increase by highly trained distancse runners and no increase in speed. The famous selling plyometric boots showed no increase in running economy or speed as claimed. Most of these speed claims are by companies promoting plyometric products for sale. Weight training has shown to be just as effective to increase running economy as plyometric without the high risk of injury. Speed training using fartlek, tempo, intervals , and especially hills builds muscular fitness beyond that which you get with weight or plyometrics training since it strengthens muscles to meet the specific demands of sprinting or running. In my opinion plyometric routines are best left for college-aged runners under the guidance of experienced coaches, since injuries may result if the exercises aren't performed properly.r