I recieved a sample of Speed Xtreme. Let me tell you first hand it works. I only did cardio 30 minutes, but I could have gone another 30 with no problem. After my cardio I worked my shoulders and hamstrings. I kept adding weight my reps even increased. Great stuff. I want to try Oxy Eca next hint hint lol.. Then I will choose which one I will use for more energy for my workouts.