Effects of magnesium supplementation on testosterone levels of athletes and sedentary subjects at rest and after exhaustion.

Plain-language summary

This study looked at whether magnesium supplements raise testosterone in athletes and in sedentary men, at rest and after exercising to exhaustion. Thirty healthy men aged 18 to 22 were split into three groups of ten for four weeks: sedentary men taking magnesium, tae kwon do athletes taking magnesium, and tae kwon do athletes taking none. At rest, free testosterone in the sedentary men taking magnesium went from 17.2 to 17.5 pg/ml, a rise of about 1 percent, and total testosterone from 620 to 632 ng/dl, about 2 percent. In the athletes taking magnesium, free testosterone went from 17.8 to 22.2 pg/ml, about 25 percent, and total from 624 to 667 ng/dl, about 7 percent. In the athletes taking no magnesium, free testosterone went from 16.3 to 18.8 pg/ml, about 15 percent, and total from 642 to 699 ng/dl, about 9 percent. The authors conclude that both exercise and magnesium raised testosterone, and that the rise was larger in men who trained. The figures come from the paper's tables, not its abstract.

Key findings

• At rest, magnesium on its own moved testosterone very little: about 1 percent for free and 2 percent for total in the sedentary men who took it.
• The athletes who took magnesium had the largest rise in free testosterone, about 25 percent at rest.
• The athletes who took no magnesium also rose, about 15 percent free and 9 percent total, more than the sedentary men who did take it.
• The authors conclude that both exercise and magnesium raised free and total testosterone, with the bigger rise in men who trained.