Which supplement works better to improve cycling performance: arginine or tryptophan?

Ratings at a Glance

Supplement	Effectiveness Rating	Confidence Rating
Arginine
Tryptophan

Effectiveness Rating: Arginine vs Tryptophan

The effectiveness rating is a measure of the supplements' ability to improve cycling performance. This rating answers the question of whether or not a supplement does what it claims. The evidence backing up tryptophan is great, while the evidence backing up arginine is good. Tryptophan should be able to improve cycling performance more effectively, however both supplements should provide positive results.

Confidence Rating: Arginine vs Tryptophan

Another factor to take into account when comparing supplements is the confidence rating. This rating is a measure of how valid each supplement's effectiveness rating is. Remember, the confidence rating is a measure of how much you can trust the effectiveness rating. This rating is based on how many studies are included in the database on a supplement's claims. Ideally, you want a high effectiveness AND confidence rating.

Both arginine and tryptophan have low confidence ratings. This means neither supplement has an adequate amount of research to back up this claim. A low confidence rating questions the validity of the effectiveness rating.