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Experimental Physiology


LGD-4033, a selective androgen receptor modulator, and MK-677, a growth hormone secretagogue, are becoming increasingly used amongst recreationally-active demographics. However, limited data exist describing their effects on health- and androgen-related biomarkers. The purpose of this case study is to report changes in body composition and biomarkers during and after continued co-administration of LGD-4033 and MK-677. We additionally aimed to examine muscular strength and intramuscular androgen-associated biomarkers relative to non-users. A 25-year-old male ingested LGD-4033 [10 mg] and MK-677 [15 mg] daily for 5 weeks. Blood and body composition metrics were obtained pre-, on-, and post-cycle. One repetition maximum (1RM) leg and bench press, as well as intramuscular androgens, and androgen receptor (AR) content were analyzed on-cycle. We observed pre- to on-cycle changes in body composition [BM:Δ+6.0%; LBMtotal:Δ+3.1%; LBMtrunk:Δ+6.6%; LBMappendicular:Δ+4.3%; FMtotal:Δ+15.4%; FMtrunk:Δ+2.8%; FMappendicular:Δ+14.8%], bone [BMC:Δ-3.60%; area:Δ-1.1%; BMD:Δ-2.1%], serum lipid- [cholesterol:Δ+14.8%; triglycerides:Δ+39.2%; LDL-C:Δ+40.0%; HDL-C:Δ-36.4%], liver- [AST:Δ+95.8%; ALT:Δ+205.0%], and androgen- [free testosterone:Δ-85.7%; total testosterone:Δ-62.3%; SHBG:Δ-79.6%] associated biomarkers; however, all variables returned to pre-cycle values post-cycle, aside from FMtotal, FMappendicular, bone area, total cholesterol, and LDL-C. Follicle stimulating hormone (FSH) was below clinical reference values on- [1.2IU/L] and post-cycle [1.3IU/L]. Intramuscular AR [-44.6%], testosterone [+47.8%], and dihydrotestosterone [+34.4%] in addition to 1RM leg press and bench press [+39.2%; +32.0%] were different in the case subject compared to non-users. These data demonstrate LGD-4033 and MK-677 increased several body composition parameters, whilst negatively impacting bone and several serum biomarkers. Given the sparsity of data in recreationally-using demographics, further research is warranted to elucidate the acute and chronic physiological effects of these anabolic agents.


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