Ostarine (MK-2866) (Enobosarm)
Ostarine is the most well-known SARM, and it is also the most research backed. This selective androgen receptor modulator (SARM) has been studied and proven to improve lean body mass and physical function. It also increases tendon strength, ligament health, bone density and encourages collagen turn-over. It is one of the least suppressive and minimally androgenic, making it a prime candidate for therapeutic purposes moving forward, and assisting in muscle retention/growth without the ramifications of severe androgen related side effects.
Studies involving Ostarine have been positive. Merck presented the results of a phase 2 clinical trial evaluating Ostarine (MK-2866) in patients with cancer induced muscle loss (cancer cachexia) at the Endocrine Society Annual Meeting in Washington in 2009. 159 cancer patients were randomized and received placebo, 1mg or 3mg Ostarine daily for 16 weeks. Ostarine treatment led to significant increases in lean body mass (LBM) and improvement in muscle performance measured by stair climbing in patients. Another study showed significant improvement in the ability of healthy, elderly men and women to climb stairs in a phase2A study. Elderly men and women improved climbing stairs in speed and power, accompanied by significant increases in LBM and decreases in fat mass after only 86 days. Enobasarm is the most well characterized clinically and has consistently demonstrated increases in LBM and better physical function across several populations, along with a lower hazard ratio for survival in cancer patients.
Ostarine (MK-2866) is mainly used for cutting (dropping body fat) with muscle and strength preservation but also for re-composition (gaining muscle and losing body fat simultaneously). Muscle preservation is the goal while cutting, not building muscle and strength. Often times when we are at a calorie deficit for weight loss we also lose some muscle mass. Ostarine helps prevent this from happening while at the same time helping prevent water retention. During re-composition, calories should be adequate for weight maintenance, not weight loss.
Most SARM cycles are done for 6-8 weeks. Suppression of natural testosterone can occur with both SARMS. Low-Testosterone related sexual dysfunction and other androgen deficiency related side effects are less likely to occur with Ostarine, they are reported more often from Ligandrol users. If you are already on testosterone therapy, you would simply continue that treatment at the same time. Completing a PCT (post cycle therapy) protocol is recommended in both cases after completing the 6-8 weeks of treatment.