What goes under gym shorts depends on the shorts and the support or coverage you prefer. Unlined shorts leave the underlayer choice to you. A built-in liner may replace separate underwear when it fits comfortably and is intended to be worn that way. A longer fitted layer, athletic supporter and protective cup are different products.
Identify what you are buying
| Item | Main clothing job | Check |
|---|---|---|
| Athletic briefs or boxer briefs | Separate everyday training underlayer | Pouch, leg opening, seams and waistband with your outer short |
| Built-in brief liner | Integrated underlayer with relatively little leg coverage | Edge pressure and coverage while moving |
| Longer fitted liner | Integrated support/coverage down the thigh | Hem riding, seam position and separate liner size |
| Compression-style shorts or tights | A separate close-fitting layer | Comfort and coverage; a marketing label is not a medical benefit |
| Athletic supporter | Pouch held by a waistband and straps | Correct product sizing and whether it is designed to hold a cup |
Should you wear underwear with lined shorts?
Many integrated liners are intended to act as the underlayer. Adding underwear is not automatically wrong, but it introduces another waistband and set of seams. Try the arrangement at home: sit, squat comfortably and move the leg. If the liner does not suit you, an unlined short with underwear you already like may be easier than adding layers to compensate.
Check the exact product description. “Lined” can mean a brief, a longer fitted liner or something else. The label does not tell you how it will feel around your thigh or whether its phone pocket accommodates your device.
If the legs keep riding up
Inspect the point where the liner hem meets your thigh. A too-tight opening, insufficient rise or friction between layers can feel similar. Try another cut rather than assuming the entire garment needs a larger waist. Longer is not always better; a long liner with an uncomfortable seam can be less useful than a shorter one that stays where you want it.
Check seated comfort too. The outfit you use on a bicycle or rowing machine spends time folded at the hips; standing in a changing room does not reveal every pressure point.
How an athletic supporter differs
A supporter generally uses a pouch, waistband and rear straps instead of the full seat of ordinary briefs. Follow its manufacturer’s measurements and fit directions; do not apply a universal instruction to place every waistband at the same point. The pouch should feel comfortable and the straps should lie without twisting or painful pressure.
Some supporters and compression shorts are designed with a pocket for a protective cup. A plain liner or ordinary compression short is not the same as impact protection. For a sport that calls for a cup, follow the sport’s requirements and the specific cup/carrier instructions. Do not put an incompatible cup into a garment that was not designed to hold it.
Medical compression is a separate decision
Do not assume a close-fitting training short provides a prescribed level of compression or treats circulation problems. If a clinician has recommended medical compression, use the actual product and directions they specify. For normal shopping, judge the underlayer by fit, seams, cleaning and the job it needs to do.
Cleaning and trying on
Underwear, liners and supporters contact skin closely; use a clean underlayer for training and wash used items according to the label. Dry fully before storing. Check hygiene-related return restrictions before ordering several sizes, and follow the retailer’s instructions during a try-on. Avoid trimming a liner unless you have decided to keep the short and accept how the change may affect its fit.
Common questions
Do I need a supporter for ordinary gym training?
It is not a universal requirement. Choose the support arrangement that feels comfortable, and follow any activity-specific protective-equipment rule.
Can a liner prevent all chafing?
No. Seam placement, fit, sweat and repeated contact still matter. Persistent irritation is a reason to stop and address the cause.
Which shorts should I compare?
Compare the exact lined and unlined versions. Our gym-shorts guide distinguishes those choices, and my Ten Thousand review gives a personal reference point.
Keep reading
Sources and review notes
Sources reviewed November 2, 2026.
