• Declining testosterone is not a symptom of old age
• Cortisol suppresses the utilization of testosterone
• Men with high cortisol exhibit symptoms of Low T regardless of T level
• Men with high levels of cortisol and low T exhibited low leadership levels
• Psychology study: men in a sports contest who were offered a rematch would take it if they had low cortisol, but not if they had high cortisol
• TSR: testosterone suppression response

Listed references

(not an endorsement)

• http://www.ergo-log.com/hornygoatweedcortisol.html
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3669033/
• https://www.ncbi.nlm.nih.gov/pubmed/23439798
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2727271/
• https://www.sciencedaily.com/releases/2011/06/110607121129.htm
• https://news.utexas.edu/2010/09/27/stress-hormone-blocks-testosterones-effects-study-shows
• https://www.forbes.com/sites/susanadams/2015/08/26/do-your-testosterone-and-cortisol-levels-dictate-your-leadership-ability/#f1189f57dbb0
• http://buckeyepmreastland.com/chiropractic/columbus-chiropractor/harvard-study-on-testosterone-and-success/
• https://blogs.wsj.com/corporate-intelligence/2014/03/25/a-high-stakes-battle-over-testosterone/
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5128352/
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3880087/
• https://www.ncbi.nlm.nih.gov/pubmed/26302434
• https://www.nytimes.com/2008/04/19/business/19online.html
• https://itestosterone.com/longjack-testosterone/
• https://www.gentechnutrition.com/blogs/news/ashwagandha-vs-tribulus-terrestris-the-best-natural-testosterone-booster
• https://www.nytimes.com/2017/03/28/well/testosterone-therapy-is-popular-but-studies-are-mixed.html
• http://jaha.ahajournals.org/content/2/6/e000272.full
• http://newsroom.ucla.edu/releases/use-of-testosterone-therapy-and-249918
• https://www.sciencedaily.com/releases/2011/06/110607121129.htm
• https://www.ncbi.nlm.nih.gov/pubmed/25548978
• https://www.ncbi.nlm.nih.gov/pubmed/23723641
• https://www.ncbi.nlm.nih.gov/pubmed/18068966
• https://www.ncbi.nlm.nih.gov/pubmed/25849625
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3850326/
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4045980/
• https://www.ncbi.nlm.nih.gov/pubmed/21116018
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3551978/
• https://www.ncbi.nlm.nih.gov/pubmed/24310211
• https://www.ncbi.nlm.nih.gov/pubmed/15729618
• https://www.ncbi.nlm.nih.gov/pubmed/23243445
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4085925/
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3433727/
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4085925/