If you’re a guy who loves running, chances are you’ve noticed something unique about your shorts: that built-in liner. Maybe you’ve wondered, “Why not just wear normal shorts and underwear?” Or maybe you’ve felt the difference on a long run and realized liners actually do serve a purpose.
For recreational runners, weekend warriors, and even first-time joggers, understanding why men’s running shorts have liners can change how comfortable—and effective—your workouts feel.
The Real Reason Running Shorts Have Liners
Running is different from other workouts. Unlike lifting weights or shooting hoops, every stride in running creates constant friction between your legs, waistband, and underwear. That’s where liners step in:
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Reduce Chafing – Liners act as a barrier, preventing painful thigh and groin irritation.
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Moisture Control – Most liners are made of sweat-wicking fabric that keeps you dry when things heat up.
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Support & Stability – Liners hold everything in place, offering light compression so you’re not adjusting mid-run.
Think of them as the running version of built-in armor—lightweight, supportive, and designed for the specific demands of logging miles.
Why Not Just Wear Underwear?
A lot of new runners try wearing boxers or briefs under running shorts, only to regret it after a few sweaty miles. Here’s why liners beat underwear every time:
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Boxers bunch up and cause friction.
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Cotton briefs trap sweat, leading to discomfort and even rashes.
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Extra layers feel heavy, especially on long runs or humid days.
Liners are designed for movement. They’re seamless, breathable, and built into the shorts for a reason.
Different Types of Liners in Men’s Running Shorts
Not all liners are the same. Choosing the right one depends on your comfort and running style:
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Brief Liners – Snug and supportive, these are the most common. Perfect for guys who want a “minimal” feel.
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Boxer-Brief Liners – Offer more coverage and compression, great for trail running or long distances.
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2-in-1 Shorts – Feature a built-in liner with a looser outer layer, giving you the look of gym shorts but the support of running gear.
Benefits Beyond Running
Even if you’re not training for a marathon, liners make sense for active guys. Whether you’re:
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Doing HIIT workouts at the gym
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Playing weekend basketball
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Or hiking in the summer heat
…the liner keeps you comfortable, supported, and free from distractions.
Tips for Choosing the Right Running Shorts
When shopping for your next pair, keep these in mind:
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Material Matters – Look for moisture-wicking fabrics like polyester blends.
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Length – Shorter inseams (3–5 inches) are common among serious runners for mobility, while longer lengths (7–9 inches) provide more coverage.
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Liner Type – Try different liner styles until you find the one that feels best for your body.
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Try Before You Buy – What feels supportive to one runner may feel restrictive to another.
Caring for Running Shorts with Liners
Since liners are built-in, proper care keeps them fresh and long-lasting:
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Wash in cold water to preserve fabric elasticity.
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Skip fabric softener—it clogs moisture-wicking fibers.
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Hang dry whenever possible to prevent wear.
Conclusion & Call-to-Action
Men’s running shorts have liners for one reason: performance. They’re designed to keep you comfortable, dry, and supported while you run. So next time you’re tempted to throw on old gym shorts, remember—liners aren’t just an extra feature, they’re your secret weapon for a smoother, more enjoyable run.
Ready to upgrade your gear? Test out different liner styles and see how they change your running experience. Your miles—and your skin—will thank you.