i googled this for you. there is no scientific proof that these have any impact that i can find. i've used this combo for multiple cycles - from nelson montan's suggestion - and the recovery with all of these compounds is great, almost like a transition rather than coming off. i use 4g trib/3g maca/3g avena sativa.
WHAT EXACTLY IS MACA ROOT?
Maca is a root that grows in the high mountains of Peru. Rich in nutritional content (potassium, and higher levels of calcium than in milk), maca is a natural hormonal balancer which provides great health benefits for both, men and women.
Due to its high nutritional value, maca is not only popular as a sexual libido enhancer and menopause symptoms savior, but also greatly affects energy, stamina, depression, memory, and more.
As Beth M. Ley, Ph.D. states on her book Maca Adaptogen & Hormonal Regulator: "Some researchers note than when the body is well-nourished and balanced (in homeostasis), overall health improves, libido rises and depression abates." pg. 15 (Handbook available here!)
WHAT WILL MACA DO FOR YOU?
Maca: Sex & Libido
Maca is recommended for fertility problems, sterility, and other sexual disorders. However, in Peru maca has long been known as a potent APHRODISIAC. Research has proven maca to act on certain areas of the body that produce hormones and energizing substances, which enhance libido and increase virility.
Maca is often compared to Viagra®; however, peruvian maca does not alter circulation. Maca's amazing libido booster is a result of completely natural hormonal balancing. Maca is a safe natural product that will improve your marriage, love and sexual life by boosting your libido and stamina, and by producing a general sense of well being!.
Claims regarding Avena Sativa
Promoters say avena sativa frees up bound testosterone to free testosterone in the blood, making it more active.