Those huge locker room mouthwash dispensers should be banished, a U.K. study, published in Free Radical Biology and Medicine, finds. That minty swish hinders fitness gains. It has to do with nitric oxide, a naturally occurring substance in blood vessels, which increases during exercise to bring more oxygen to muscles. The vessels use nitric oxide as a signal, like sounding a bullhorn to the soft muscle tissue of the body, ordering it to loosen up and enable bloodflow—which makes nitric oxide irreplaceable when it comes to endurance training, hourlong runs, or any other long form of exercise. The more nitric oxide in your system, the less fatigued you’ll feel. So rinsing with mouthwash before you exercise is doing yourself a huge microvascular disservice.
Mouthwash before exercise could even lead to post-exercise hypotension. PEH is a phenomenon that isn’t fully understood yet, but this study illuminates a very important part of the puzzle.
In the study, salivary samples from runners showed that antibacterial mouthwash reduced nitric oxide’s effectiveness between 60 percent and 100 percent. So when it comes to keeping fresh breath at the gym, have a Tic Tac instead.
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