Comparing Sustained Energy and Perpetuem
•Sustained Energy is neutrally (a.k.a. "plain") flavored. Perpetuem is available in three options: an orange-vanilla "Dreamsicle" flavor, a caffeinated caffe latte flavor (12.5 mg of caffeine per scoop), and in an unflavored/plain version.
•Perpetuem contains lyso-lecithin fat, whereas Sustained Energy does not.
•Perpetuem contains tribasic sodium phosphate, which is a tremendous lactic acid buffer. Sustained Energy does not contain this nutrient.
•Both fuels contain l-carnosine (an antioxidant that also buffers lactic acid), l-carnitine (to promote fatty acid utilization), and chromium polynicotinate (to stabilize blood sugar levels).
Bottom line: With Sustained Energy and Perpetuem, you have two great long distance fuel choices. When exercise goes beyond about two hours, you can use either product as your primary or sole fuel, in any combination with each other or any other Hammer Nutrition fuel.
That said, we have noted that Sustained Energy may be the ideal fuel choice when endurance exercise intensity is at a higher level (approximately 70-85% MHR), whereas Perpetuem may be a more attractive choice the longer the athlete goes and when exercise intensity is at a more aerobic pace (under 70% MHR). Additionally, over the years we have noted that Sustained Energy may be the ideal choice for very lean athletes (the "high metabolizer/hyper-metabolic" types), while Perpetuem - with its added healthy fat component - may be the ideal choice for athletes with a naturally higher body fat percentage. The rationale for this suggestion is that athletes with a higher body fat percentage have a greater volume of calories available from body fat stores, which the lyso-lecithin component of Perpetuem may effectively assist in accessing for use as energy.
Again though, because the applications for Sustained Energy and Perpetuem are identical, either fuel can be used as the primary-to-sole fuel during prolonged bouts of exercise. Test each product in your long-duration workouts, under a variety of conditions, to find which product works best for you!