Understood. I do some HIIT training on my off days, mostly sprints. I will up the intensity. I guess I should have reworded my post. I was not looking for a magic pill that instantly ups endurance but rather a PH that lends itself to lean muscle gains. With the exception of sports like footbal (lineman) the leaner the better. In hockey you wear about 20 lbs of gear, any extra BF is just dead weight. More weight wears you down faster and slows your sprints and explosive speed. I was not sure if any of the PH's had an affect on endurance. Thanks for the explanation.