Arginine is an amino acid that increases your body's production of nitric oxide, which is thought to increase blood flow to the muscles for a greater exchange of nutrients. It's a popular addition to many supplements thought to increase performance. "Even though there's a tiny bit of supportive research for arginine's increasing performance, it's not overwhelmingly positive," says Chad M. Kerksick, ., assistant professor of exercise physiology at the University of Oklahoma. He took part in a study at Baylor University, in Texas, that found a small increase in bench-press strength with arginine. But a 2006 study published in the Journal of the American Medical Association found that taking a daily supplement with 9 grams of arginine may cause heart attack or even death in men with known—and unknown—heart disease. That study was forced to end early.
If a young man's low testosterone is a problem for a couple trying to get pregnant , gonadotropin injections may be an option in some cases. These are hormones that signal the body to produce more testosterone. This may increase the sperm count. Hedges also describes implantable testosterone pellets, a relatively new form of treatment in which several pellets are placed under the skin of the buttocks, where they release testosterone over the course of about three to four months. Injections and nasal gels may be other options for some men.