To my knowledge, there has yet to be a single independant study supporting the effacacy of tribulus as a muscle building supplement. In the one study of which I am aware, the conclusion was that the supplement does not assist in the development of muscular tissue (although that study has been criticized by some on this board based on the dosage involved in the test group).
In my opinion, absent scientific validation, such as exists with creatine, there are probably better places/supplements for your money to be spent.
I'm sure others will disagree.
I hear you. I love scientific facts, but at the same time, I try to remember that every case study has it's flaws, i.e. biases, omitted information, discrepancies in testing patterns, etc.
There is even still some controversy over whether or not Testosterone helps build muscle.
Several of my friends compete at national and pro levels, and not one of them has ever said that increased Test has proven useless for their goals. Those injections only helped!
Researching is smart, but don’t forget to look outside the confines of the lab.
REAL WORLD RESULTS are important, too. Never dismiss information merely because it is anecdotal.
Here are some Tribulus facts and how it has been used over the years:
http://www.nutros.com/nsr-02016.html