NO supplements = the biggest scam in sports nutrition since GH boosters, and irony of all irony, the same main ingredient (arg) used in both scams! I love this business! 
Take home: from this review:
"In this regard, training status of the subjects seems to be an important factor linked to the ergogenic effect of NO supplementation. Studies involving untrained or moderately trained healthy subjects showed that NO donors could improve tolerance to aerobic and anaerobic exercise. However, when highly trained subjects were supplemented, no positive effect on performa...nce was indicated."
The Effect of Nitric-Oxide-Related Supplements on Human Performance
Sports Medicine:
1 February 2012 - Volume 42 - Issue 2 - pp 99-117
doi: 10.2165/11596860-000000000-00000
Review Abstract:
The Effect of Nitric-Oxide-Related Supplements on Human Perf... : Sports Medicine
Take home: from this review:
"In this regard, training status of the subjects seems to be an important factor linked to the ergogenic effect of NO supplementation. Studies involving untrained or moderately trained healthy subjects showed that NO donors could improve tolerance to aerobic and anaerobic exercise. However, when highly trained subjects were supplemented, no positive effect on performa...nce was indicated."
The Effect of Nitric-Oxide-Related Supplements on Human Performance
Sports Medicine:
1 February 2012 - Volume 42 - Issue 2 - pp 99-117
doi: 10.2165/11596860-000000000-00000
Review Abstract:
The Effect of Nitric-Oxide-Related Supplements on Human Perf... : Sports Medicine
