Best Underwear for the Gym: What to Look For (And What to Avoid)
by Chelsea Guy
Let’s be honest: most people spend more time choosing their gym shoes than thinking about their underwear.
That is a mistake.
When you are training, your underwear is doing serious work. It is dealing with sweat, movement, heat, friction, and repeated stretching. If the wrong pair is underneath it all, you will feel it fast, riding up, clinging, overheating, bunching, or creating a chafing situation you did not ask for. ThunderWear’s Sports Quick Dry range is built specifically around moisture-wicking, cooling fabric, no-chafing comfort, and a softer jacquard waistband that “hugs, not squeezes,” which is exactly the kind of feature set gym underwear needs.
So if you are wondering what makes the best underwear for the gym, here is the real checklist.
1. Look for moisture-wicking fabric
At the gym, sweat itself is not the problem. Trapped sweat is.
The best gym underwear should help move moisture away from the skin, dry quickly, and stay comfortable when the session gets hot. ThunderWear’s Sports Quick Dry fabric is described on the site as moisture-wicking, cooling microfiber with spandex, and the men’s Sport Quick Dry trunks repeatedly highlight “smooth buttery soft and cooling quick dry fabric” plus moisture wicking. That makes the sports range the clearest fit for training sessions, cardio, strength work, and high-sweat days.
2. Look for support without squeeze
Good gym underwear should feel secure, but not restrictive.
If it is too loose, it shifts. If it is too tight, it digs in, traps heat, and becomes annoying halfway through your session. ThunderWear’s men’s trunks are designed with the brand’s Ballroom™ concept for extra space and breathability, while the waistband is described as soft and supportive rather than harsh or compressive. That balance matters in the gym because you want support that works with movement, not against it.
3. Look for anti-chafing comfort
This is the bit people often skip, until leg day, treadmill work, or a humid walk home makes it impossible to ignore.
The best underwear for the gym should reduce friction, stay in place, and move cleanly with your body. ThunderWear’s Sport Quick Dry trunks explicitly call out “no chafing” on product pages, which is exactly the kind of wording you want to see for training underwear.
This is also where fabric and fit work together. A good gym pair should not bunch, rub, or turn into a distraction halfway through your workout. It should quietly do its job so you can focus on training, not on adjusting yourself between sets. ThunderWear’s product positioning leans heavily into that “zero fuss care, maximum all-day comfort” space, which fits this point well.
4. For women, look for breathable comfort that still feels great to wear
Women’s gym underwear needs a slightly different conversation, but the same basic rule applies: comfort first, friction second, and no nonsense.
ThunderWear’s women’s range is built around modal boy shorts rather than a dedicated women’s sports quick-dry line. That makes the women’s modal range a strong fit for impact training, studio sessions, walking, recovery days, and all-day comfort around workouts.
What to avoid
If you are buying underwear for the gym, avoid anything that creates extra friction, heat, or distraction.
That usually means:
- underwear that is not moisture-wicking for high-sweat sessions
- waistbands that squeeze too hard
- pairs that shift around too much
- rough seams or poor fit
- old pairs that have lost shape and support
ThunderWear’s own fabric guide makes the distinction clearly: Sports Quick Dry is the moisture-wicking, cooling performance option, while Modal is the softer, breathable comfort option. That is useful because not every pair needs to do the same job. Hard training days usually call for the sports fabric. Softer sessions and everyday comfort can lean modal.
The ThunderWear take
If you are training hard, the best underwear for the gym is the pair you forget you are wearing.
It should wick sweat, breathe well, reduce chafing, support movement, and stay comfortable when the workout gets messy. That is why ThunderWear’s Sports Quick Dry men’s range is such a strong gym fit, and why the breathable women’s modal range works well when comfort is the priority.
Because once your base layer is right, you can get on with the actual workout.
Final thoughts
Gym underwear should not be an afterthought.
The right pair can make training more comfortable, less distracting, and a lot less sweaty in all the wrong ways. So if you are upgrading your gym kit, start with the first layer.
The goal is simple: better comfort, better support, better training.