How to Prevent Chafing During Long Runs

Few things derail an otherwise perfect long run quite like chafing. That innocent friction that starts as mild discomfort can escalate into raw, bleeding skin that makes every remaining kilometre miserable. For marathon and ultra runners, chafing prevention isn't a minor comfort consideration—it's essential race preparation.

The good news is that chafing is almost entirely preventable with the right strategies. This guide covers why chafing occurs, which areas are most vulnerable, and proven methods to keep your skin intact through even the longest efforts.

Understanding Chafing

Chafing occurs when repeated friction damages the outer layer of skin. This happens when skin rubs against skin (inner thighs, underarms), when clothing rubs against skin (bra straps, waistbands, vest straps), or when equipment rubs against clothing or skin (running vest, hydration pack).

Three factors combine to create chafing:

• Friction: Repetitive rubbing motion, which increases with distance and time
• Moisture: Sweat and humidity soften skin, making it more vulnerable to damage
• Salt: As sweat evaporates, salt crystals remain and act like sandpaper

This is why chafing often appears in the later stages of long runs—the cumulative friction combined with salt buildup and softened skin creates perfect conditions for damage.

Common Chafing Zones

Understanding where chafing typically occurs helps you target prevention efforts effectively. While individual anatomy affects specific problem areas, these zones are vulnerable for most runners:

Inner Thighs

The inner thigh is perhaps the most common chafing zone, especially for runners whose thighs touch during the running gait. This skin-on-skin friction can become severely painful during long distances.

Nipples

Particularly problematic for male runners and women in ill-fitting sports bras. The constant rubbing of shirt fabric can cause bleeding that's visible through clothing—an unpleasant sight at race finish lines.

Underarms

Arm swing means constant friction in the underarm area. Seams and tags in this zone exacerbate the problem.

Sports Bra Areas

Band areas, strap edges, and anywhere elastic contacts skin are prime chafing zones for female runners.

Waistband

Where shorts or tights meet your torso, especially if clothing shifts during running.

Anti-Chafe Products

A variety of products create a protective barrier between skin surfaces or between skin and fabric. Finding what works for you may require some experimentation.

Petroleum-Based Products

Classic petroleum jelly (Vaseline) has been preventing chafing for generations. It's inexpensive, widely available, and effective. Apply a thick layer to vulnerable areas before running. The main drawback is messiness and potential to stain clothing.

Purpose-Made Anti-Chafe Balms

Products like Body Glide, Squirrel's Nut Butter, and 2Toms SportShield are specifically designed for athletic use. They typically:

• Apply more cleanly than petroleum jelly
• Come in convenient stick or roll-on formats
• Are less likely to stain technical fabrics
• May include additional skin-beneficial ingredients

These products work by creating a dry, friction-reducing layer on the skin. Most need reapplication for events longer than about three hours.

Nipple Covers and Tape

For nipple chafing, adhesive covers or simple tape (medical tape, sports tape, or purpose-made products like NipEaze) create a barrier between skin and fabric. This is often more reliable than balms alone for this sensitive area.

Clothing Strategies

What you wear significantly affects chafing risk. Smart clothing choices can eliminate or reduce the need for anti-chafe products.

Fabric Choice

Technical moisture-wicking fabrics help keep skin drier than cotton, reducing one of the three chafing factors. Look for polyester blends, merino wool, or purpose-designed running fabrics. Avoid 100% cotton, which absorbs sweat and stays wet against your skin.

Seam Construction

Flatlock seams lie flat against the skin rather than creating raised ridges. Many running-specific garments feature flatlock construction in high-friction areas. Avoid shirts with prominent seams across the chest or under the arms.

Fit Matters

Clothing that's too loose shifts around and creates friction. Clothing that's too tight can dig in and rub. The ideal fit is snug enough to stay in place but not restrictively tight. Compression shorts, for example, prevent thigh chafing by eliminating skin-on-skin contact.

Compression Wear

For inner thigh chafing, compression shorts or half-tights are often the most effective solution. The fabric acts as a barrier between thighs, and the compression keeps everything in place. Many runners wear compression shorts under their regular running shorts.

Running Vest Considerations

Running vests introduce additional chafing risks from straps, buckles, and the back panel. To minimise vest-related chafing:

• Ensure proper fit—a vest that moves independently of your body creates friction
• Apply anti-chafe products under straps and along contact edges
• Check for rough seams or strap edges that could irritate
• Adjust strap tension to be secure but not overtight
• Consider wearing a close-fitting base layer under your vest

As your vest gets wet from sweat, friction can increase. Some runners apply extra anti-chafe product to shoulder strap areas during long runs or at aid stations during races.

Application Tips

How you apply anti-chafe products matters as much as what you use:

• Apply before dressing: Put on anti-chafe products before clothing, allowing them to create a proper barrier
• Be generous: A thin smear is less effective than a proper layer. Don't skimp.
• Cover the whole zone: Chafing occurs at the edges of protected areas, so extend coverage beyond the obvious friction point
• Carry extra for ultras: Pack a small container of your preferred product for reapplication during very long events
• Test in training: Find what works for you before race day

Mid-Run Remedies

Despite best efforts, chafing sometimes develops during a run. If you feel irritation starting:

• Address it immediately—early intervention prevents escalation
• Apply more anti-chafe product if you're carrying some
• Adjust clothing to eliminate or reduce the friction point
• At aid stations (races) or your car (training), apply additional lubricant
• If bleeding, cover with a bandage or tape to prevent further damage

If chafing becomes severe during a race, most medical tents can provide petroleum jelly, bandages, or other remedies. Don't suffer silently—these minor interventions can save your race.

Treating Chafed Skin

If chafing does occur, proper treatment promotes faster healing and prevents infection:

1. Clean gently: Wash the area with mild soap and lukewarm water. This will sting but is necessary.
2. Pat dry: Don't rub—gently pat the area dry with a clean towel.
3. Apply healing ointment: A barrier cream like Bepanthen, or antiseptic like Savlon, protects healing skin.
4. Let it breathe: When possible, leave chafed areas exposed to air rather than covered by clothing.
5. Avoid friction: Don't run again until the area has healed enough that further friction won't cause damage.

Building Chafe Resistance

Interestingly, regular running can toughen skin in common chafing zones. Many experienced runners find they're less prone to chafing than when they started. This doesn't mean you should deliberately chafe to "toughen up"—that's counterproductive—but it does explain why problems often decrease with consistent training.

Gradual increases in long run distance allow your body to adapt. If you're training for your first marathon, your skin (like your muscles and cardiovascular system) needs time to adapt to the demands you're placing on it.

Chafing is a solved problem for most runners who take prevention seriously. Identify your vulnerable areas, experiment with anti-chafe products and clothing solutions during training, and arrive at race start lines confident that discomfort won't derail your goals. Your skin will thank you.