Turkesterone is a naturally occurring ecdysteroid and the primary bioactive compound in the plant, Ajuga Turkestanica. Ecdysteroids are a class of compounds that are structurally similar to androgens. Ecdysteroids are well studied as plant & insect growth factors.
Although there is a lack of trials currently available for humans, promising evidence is available for in vitro studies on human muscle fibers as well as a multitude of animal models showing enhanced growth rates with ecdysteroid ingestion. In fact, ecdysterone, a compound chemically similar to Turkesterone, was suspected to be used by Russian Olympic athletes in the 1980's (The "Russian Secret") which led to an explosion of scientific research on the application of ecdysteroids in athletic performance.
One particular study found that "[Ecdysteroids] exhibited a strong hypertrophic effect on the fiber size of rat soleus muscle that was found even stronger compared to the test compounds metandienone (dianabol), estradienedione (trenbolox), and SARM S 1, all administered in the same dose (5 mg/kg body weight, for 21 days)."
Some researchers describe ecdysteroids as "behaving similar to anabolic steroids putatively without the androgenic effect". The lack of androgenic action leads ecdysteroids to have a favorable safety profile compared to hormonal supplements.
Of the most commonly studied ecdysteroids, Turkesterone appears to be the most anabolic. More human research is needed to confirm the effects Turkesterone on athletic performance, but initial studies have been encouraging for athletes.
Turkesterone+ also includes added Ashwagandha & Black Pepper extract.
Ashwagandha has been used for centuries in ayurveda, and has been found to reduce serum cortisol levels in humans. Cortisol is the "stress hormone" in humans, and has been shown to have catabolic (muscle depleting) effects. Initial studies also indicate a positive effect on strength performance & testosterone, although more human studies are needed to confirm effects and form a consensus on proper dosage.
Black Pepper is a source of piperine, a molecule that does not do much on its own but can inhibit enzymes that would attack other molecules. Due to this, it is ingested alongside some supplements to increase their absorption rates
REPP Sports Turkesterone+ formula contains doses similar to those found in clinical studies with positive outcomes.