Best Underwear for the Gym: Men's Guide
It is the layer nobody sees and everybody feels. Bad gym underwear means chafing on leg day, adjusting yourself between sets, and swampy discomfort by the time you hit cardio. Good gym underwear disappears. You forget it exists, which is exactly the point.
Why Regular Underwear Fails at the Gym
Your everyday cotton boxers or briefs were designed for sitting at a desk, not for deep squats. Cotton absorbs sweat and holds it against your skin. The loose fit bunches under compression gear. The seams rub in all the wrong places once you start moving.
Gym underwear is built for a different job: stay put, stay dry, and get out of the way. Once you switch, going back feels like training in jeans.
The Three Styles That Work
Boxer briefs are the default for most guys, and for good reason. They cover the thigh enough to prevent skin-on-skin chafing, they stay in place under joggers or shorts, and the longer leg does not ride up the way regular boxers do. If you only buy one style, make it this.
Trunks are the shorter version. Same support, less leg coverage. They work well if you run hot or prefer less fabric, but on heavy leg days the shorter leg can ride up. Fine for upper body days.
Compression shorts or jock-style performance briefs are for guys who want maximum lockdown. They keep everything firmly in place during explosive movements, sprints, and heavy lifts. Some guys wear them as the only layer under joggers. If chafing has ever ruined your week, this is your answer.
What does not work: loose boxers (they bunch and ride), regular cotton briefs (swampy by set three), and going commando in gym shorts without a liner (do not be that guy).
Fabric: The Real Decision
This matters more than the style. Look for moisture-wicking synthetics: polyester, nylon, or micromodal blends with elastane. These pull sweat off your skin and dry fast.
Merino wool blends are the premium option. Naturally odor-resistant, temperature-regulating, and soft. They cost more but last well and you can get away with fewer pairs.
Avoid 100 percent cotton for training. It is fine for the couch. In the gym it turns into a wet rag that causes exactly the chafing you are trying to prevent.
A good blend is something like 85 to 90 percent performance fabric with 10 to 15 percent elastane or spandex. That gives you the stretch to move and the recovery to keep shape.
Fit Details That Matter
The waistband should be wide, flat, and stay put without digging. A rolling waistband during squats is miserable. Look for a covered elastic band at least an inch wide.
Flat seams or seamless construction around the inner thigh prevents the rubbing that turns into raw skin on high-rep leg days. Run your finger along the seams before you buy. If you can feel a ridge, your thighs will feel it more.
The pouch should be supportive without being compressive to the point of discomfort. Contoured pouches beat flat fronts. You want separation and support, not squashing.
Leg length on boxer briefs: long enough to prevent thigh chafing, short enough not to bunch at the bottom of your joggers. For most guys that is a 5 to 7 inch inseam.
Chafing: Prevention and Fixes
Chafing happens where skin rubs skin or fabric rubs skin repeatedly, made worse by sweat and salt. The inner thighs are ground zero on leg day.
Prevention starts with the right underwear: moisture-wicking boxer briefs with enough leg coverage. If you are still getting it, anti-chafe balm on the inner thighs before training works. It is not just for marathon runners.
If you are already raw, give it a day or two, keep the area clean and dry, and do not train through broken skin in sweaty gear. That is how you get an infection.
How Many Pairs and When to Replace
Five to seven pairs if you train regularly. Never rewear gym underwear. The bacteria and odor buildup is real, and elastane does not recover fully without a wash and rest.
Replace when the elastic goes, the fabric thins, or they have a smell that survives the wash. For regular trainers, expect six to twelve months per pair depending on quality.
Wash and Care
Wash cold with your other gym clothes. Skip fabric softener, it coats the fibers and kills moisture-wicking. Hang dry or tumble low. Heat is the enemy of elastic, and dead elastic means underwear that sags by noon.
Wash them inside out to protect the outer surface and any printed waistband logos.
What About Liner Shorts?
Many training shorts come with a built-in liner. On days you wear those, the liner IS your underwear. Doubling up with underwear underneath defeats the purpose and adds bulk and heat. Trust the liner, or wear joggers with your boxer briefs. Pick one system per workout.
The Bottom Line
Gym underwear is not exciting, but it is one of those things that quietly makes every session better. Moisture-wicking boxer briefs, flat seams, a waistband that stays put. Get the fabric right and the rest follows. Your thighs will thank you on leg day.
Shop the look: KYNOS Performance Joggers | KYNOS Performance Tee