In one sentence, describe what the following article is about:

When used properly, a menstrual cup may be the best option for exercising during your period. These cups are reusable, and they can stay in place for up to twelve hours. Menstrual cups are ideal if you are doing endurance training, running a marathon, or hiking. Menstrual cups may move around during yoga, however. Once a menstrual cup is in, you should feel no discomfort, but some people may struggle with placing the cup. If you don't have a menstrual cup, buy a box of tampons instead. Tampons are not comfortable for everyone during exercise, however. If you find that you can't exercise with a tampon in, try another method instead. "Sport" tampons are designed for workouts. You can try using these if normal tampons are uncomfortable while you exercise. If you have a heavy flow, you may need more protection. Use a pantyliner in addition to a menstrual cup or tampon. Put a new one in your undies just before exercising. Pads may cause uncomfortable chafing as you exercise. They can also scrunch up as you exercise, giving you less protection than you may need. If tampons and menstrual cups don't work for you, however, pads may be your only option. The underwear should be made out of a breathable fabric such as cotton. Underwear with more coverage will be more comfortable and prevent more leaks than a thinner type, such as a thong. You can even invest in a pair of period-proof underwear, such as Thinx. These can be worn in addition to or instead of a tampon or menstrual cup. Pants and shirts that are too tight might cause discomfort, especially if you're experiencing cramps, constipation, or bloating. Instead, choose looser clothing. Make sure that your pants are dark, just in case there's a leak! For example, instead of tight leggings, wear loose sweatpants to the gym. A cotton t-shirt or tank top is perfect, especially if you don't tolerate heat well on your period.
Try using a menstrual cup. Insert a new tampon just before exercising. Apply a pantyliner if you're prone to leaks. Use pads if you can't use tampons or menstrual cups. Choose boy shorts or hipster underwear. Wear dark, loose-fitting clothing.