Taking L-arginine while doing heart rehab after a heart attack might help you feel stronger and move better, no matter how old you are, your gender, how fit you were before, or other health problems you have.

Taking a specific amino acid supplement called L-arginine every day for three weeks might make people feel less tired when they exercise, after having a heart attack and while doing heart rehab — compared to taking a sugar pill.

Taking a specific amino acid supplement called L-arginine every day for three weeks helps people who’ve had a heart attack and are in rehab walk farther in six minutes than those who take a sugar pill.

Taking L-arginine pills can raise the level of arginine in your blood, but that doesn’t always mean you’ll produce more nitric oxide or get better at exercising—sometimes it helps, sometimes it doesn’t.

Taking 6 grams of L-arginine might help young men exercise harder for longer before getting tired, by about a quarter more time than usual.

Taking 6 grams of L-arginine might help young men use less oxygen when they exercise at a steady pace, which could mean their body works more efficiently.