Nitrates and beetroot juice for endurance; you could also use arginine…

Nitric oxide (NO as its NOwn) helps to open, or dilate, blood vessels. It appears that by increasing the availability of nitrates during exercise, more NO can be produced, and blood vessels are more readily relaxed and able to supply exercising muscle. So where can you get a concentrated source of nitrates without having to eat impractical quantities of vegetables and bacon before training? Beetroot juice!

The research:

Blood pressure during exercise and the “energy cost” of running, have been consistently shown to be lower in supplemented individuals after loading up on beetroot for a few days before exercise. However, research just released is far more relevant to the high-intensity work in racket–sports. 6 days of beetroot juice supplementation improved time-trial performance in trained cyclists. Supplementation improved performance in a 10-km, maximal effort time trial compared to when the same 12 cyclists took a placebo. Over the 10km trial, average times were reduced by 12 seconds – no mean feat!

Is it worth it?

For endurance; definitely. However, this was a maximum effort trial, meaning that these results apply to many disciplines.

Our own GH releaser is full of nitrogen-containing aminos shown to work in the same way as beetroot juice to aid vasodilation and nutrient delivery!

http://www.yoursportsnutrition.com/hormonal-support/growth-hormone.html

Cermak, et al., (2012); Nitrate Supplementation’s Improvement of 10-km Time-Trial Performance in Trained Cyclists IJSNEM Volume 22, Issue 1, 2, 64 – 71