Picking out good and comfortable clothes to workout in are as essential as finding the right workout style which works for you.
Clothes can provide you with the right kind of motivation and help you burn calories faster. Hence, there is a reason we are saying it is important you stop working out in those sloppy clothes. This also extends to the basics- including the underwear you wear.
Why is this crucial?
When you workout, it is important that you are comfortable in what you wear. Your underwear is stopping you from achieving ultimate comfort and this also risks your health. This is common to both men and women.
Workout generates sweat
Think about it. When you workout, you tend to sweat it out. What follows is a build up of sweat and friction (and germs) which sticks to your body and your clothes, especially if you are not wearing the breathable type of basics. If the friction and sweat sticks between layers, it can lead to nasty bacterial infections and even UTIs.
For men, if you tend to wear your sweaty gear post workout, it can lead to excessive itching in your genitals caused by moisture trap. This condition is actually known as intertrigo. Hence, keep your ill-fitting and fancy material underwear away from the gym bag.

Always remember this:

Whether you are running, doing yoga or sweating it out at the gym, always keep your clothing diffferent from what you wear at home and what you wear at the gym. Wear something breathable and always make sure to shower after you workout.

It is also important to choose a fabric which suits your needs. Cotton is the most preferred fabric for general purpose, it is also acceptable when you indulge in light yoga exercises. But wearing fabrics like polyester or nylon to workout is good because it is actually designed to get rid of any moisture.

The same criteria extends to underwear. Try to wear something that is not too baggy and definitely not lacey, which can add too much friction down there. Classic cuts are the safest option to go for. Men should wear synthetic fabric specially made of antimicrobial quality.

Source: indiatimes.com