Best Underwear for Running (Men's 2026 Guide)

You've got the shoes dialed. You know your splits. You've put in the kilometres. So why is the layer closest to your skin still the one you haven't thought about?

For most runners, underwear is the last thing to get upgraded and the first thing to quietly cost them a run. Chafing a few kilometers in. Leg openings that creep. A seam you suddenly notice with every stride. The wrong pair will cost you minutes you trained months to find. 

The fix isn't toughness. It's better gear.

Five Things to Look For

These are the criteria worth holding any pair of running underwear against. We've covered the why behind a few of these in more detail in our guides on chafing and ride-up.

1. Moisture-wicking fabric. Cotton holds water against the skin. Performance fabric moves it away and dries fast. It's the difference between gear that disappears and gear you can't stop thinking about.

2. Anti-chafe construction. Flatlock seams, smooth panels, minimal internal stitching. Seam placement matters more than the logo on the waistband.

3. A true 5″ inseam. Enough fabric on the thigh to anchor the leg opening and resist ride-up, without veering into compression-short territory. 

4. Real breathability. Heat builds moisture, moisture builds friction, friction builds problems. Breathable design breaks the chain at the start.

5. Stable leg openings. They keep the trunk anchored to your thigh stride after stride. Skimp here and the inseam length stops mattering. 

How the Major Brands Perform on a Run

This is where the choice actually gets made. Most performance underwear is "fine" for running. The differences only show up once you're working.

Nike Pro (365 / Elite / Pro Shorts)

Strengths: Built for high-intensity, multi-sport movement. Strong moisture management, snug fit, durable construction.

Worth knowing: A true 5″ inseam isn't standard across the line, and seam placement is tuned for general training rather than a running-specific fit.

Best for: Tempo days, intervals, and gym sessions.

Under Armour Boxerjock / Tech

Strengths: True compression-style support that resists bunching, with strong sweat control and a durable synthetic blend.

Worth knowing: Compression fabric is dense by design, which traps heat and can feel restrictive on harder efforts.

Best for: High-intensity workouts and short running.

Lululemon Always In Motion

Strengths: Premium feel, soft modal blend, excellent for everyday wear and lighter sessions.

Worth knowing: Modal retains more moisture than technical mesh and dries slower, which makes it less suited to anything where sweat management is the priority.

Best for: Everyday use and occasional runs.

ruhn Agility 5″ Trunk

Strengths: Built for the mechanics of an actual run. True 5″ inseam, technical wicking fabric that dries fast, breathable panels, flatlock anti-chafe construction, reinforced leg openings, and balanced support without the heat trap of heavy compression. Close-fitting enough to stay anchored, breathable enough to run long in.

Worth knowing: Engineered for runners first, but the design - light, dry, anchored, breathable - is why a lot of customers end up wearing them for cross-training and everyday too.

Best for: Anyone who runs regularly, in any conditions.

Direct Comparison

Where ruhn Fits In

Most athletic underwear is designed to be acceptable across a wide range of activities. ruhn was designed with runners in mind. The priorities are the runner's priorities: breathability, stability, heat regulation, freedom of movement, zero chafe.

Built for the long haul, when most gear starts giving up.

The Bottom Line

The best running underwear earns its place by disappearing. It moves moisture, holds its position, doesn't chafe, doesn't overheat, and stays out of your head. If you've already invested in the shoes, the watch, the plan, and the kilometres, the layer underneath shouldn't be the weak link.

FAQ

What is the best inseam length for men's running underwear?

A 5-inch inseam tends to be the sweet spot - long enough to anchor against the thigh and resist ride-up, short enough to avoid feeling like a compression short.

Is cotton underwear okay for running?

Not for anything past a short, easy effort. Cotton absorbs sweat, holds it against the skin, and increases friction once it's wet. Moisture-wicking fabric stays lighter, drier, and more stable.

Does compression underwear prevent chafing?

Sometimes, but it isn't a complete fix. Compression can resist bunching, but it often traps heat, and heat builds the moisture that causes chafing in the first place. Stability comes from construction, not tightness alone.

Is running-specific underwear actually different from general athletic underwear?

Yes. Multi-sport underwear is engineered for a wide range of movements. Running-specific underwear is built around one: the repeated forward stride. That changes inseam length, seam placement, and fabric weight in ways that matter.

How often should I replace my running underwear?

When you start noticing it. Weaker elasticity, more bunching, fabric that feels thinner - those are signs the recovery is gone. Even good underwear has a shelf life, and no amount of design survives fabric fatigue.