Chafing in Places the Sun Doesn’t Shine: A Runner’s Guide to Staying Smooth

Last update December 19, 2025 by Etienne Durocher

Every runner loves to talk about pace, shoes, VO₂ max, races, medals, GPS watches, gels… but almost no one talks about the real menace of distance running. Not hills. Not dehydration. Not even that one friend who always says “easy run” and then takes off like they’re escaping a bear.

The true villain? Chafing.

Chafing appears silently, shows no mercy, and usually chooses the most inconvenient body parts possible. If you’ve ever finished a run walking like a penguin on vacation, you know exactly what I mean. And yes, sometimes it shows up in places where the sun doesn’t shine, blink, or dare to imagine going.

We’re going to keep things light today — because the subject is serious, the pain is real, but the explanations do not have to be. Let’s talk about what chafing is, why it happens to runners of all levels, how to prevent it, how to treat it, and how to avoid ever doing that painful sideways walk again.

What You Need to Know First

Chafing is simply irritation caused by friction. When skin rubs against skin, fabric rubs against skin, or moisture gets trapped in the wrong area, the skin barrier breaks down. This leads to redness, burning, stinging, or in dramatic cases, bleeding. If you’ve never had bleeding nipples after a long run, consider yourself blessed by the running gods.

Chafing can happen in many places: inner thighs, underarms, sports bra lines, under waistbands, nipples, feet, and yes — the mysterious folds and shadows of the groin and backside. The body is creative.

Before diving deeper, here is the one and only bullet-point section for this part:

• Chafing happens when friction, sweat, and salt crystals combine to irritate the skin, especially in areas with repetitive movement or trapped moisture.

In short: your body moves, your clothes shift, your sweat dries, salt crystals scrape, and suddenly you feel like someone sandpapered your thighs. That’s the science.

Why Chafing Happens (The Uncomfortable Truth)

Runners live in motion. That constant motion means certain areas are under repeated stress. Add moisture from sweat, rain, humidity, or long hours on the trail, and the skin becomes even more vulnerable. Heat softens the skin, cold adds layers that rub, and salt creates tiny irritants that stick to your skin like miniature knives.

For many runners, chafing shows up during longer distances, hot days, wet days, or anytime new gear hasn’t been tested properly. But even short runs can create problems if clothing fits badly or moisture stays trapped.

In other words, chafing is not a fitness failure. It’s a mechanical issue — and a very fixable one.

How to Prevent Chafing (With Humor, But Serious Results)

Let’s talk prevention. Because once you understand how chafing happens, avoiding it becomes a lot easier. The key is to think about two main elements: what touches your skin and how well you protect your skin before the run.

Clothing Choices

If you’ve been running in cotton, I’m going to gently suggest that you stop. Cotton absorbs sweat, holds it, and turns into wet sandpaper. Instead, reach for moisture-wicking fabrics designed for running. The more technical and seamless the clothing, the better your skin will feel.

Sports bras, underwear, shorts, and shirts should fit snugly but not tightly. Too tight causes rubbing. Too loose causes flapping. Either way, your skin loses.

Lubrication: The MVP

If there is a superhero in the fight against chafing, it is lubricant. And not just any lubricant. Runners have two old reliable friends: Body Glide and Squirrel’s Nut Butter. These products create a smooth barrier that keeps skin from rubbing itself raw. Apply a generous layer on inner thighs, underarms, sports bra lines, nipples, and anywhere you already know tends to get sensitive.

Lubrication is not something to be shy about. During long races, many ultrarunners reapply halfway. Consider it preventive maintenance.

Moisture Management

Sweat happens. But lingering sweat creates problems. Changing out of wet clothes quickly, choosing dry socks, and washing dried salt off the skin makes a big difference. Even a quick rinse after a run helps prevent next-day irritation.

Weather Awareness

Hot days increase sweat production. Wet days make clothing heavier and more abrasive. Cold days add layers that rub against each other. Knowing the conditions allows you to prepare with better clothing and more lubrication.

Preventing chafing is mostly about respecting friction. Once you respect friction, friction respects you.

If these tips are already saving your skin, you’ll enjoy exploring more expert guidance on the blog. Try these helpful reads:

• How to Recover Faster After a Marathon

• The Process of Carb Loading Before a Race

• Why Runners Need Strength Training More Than They Think

You can also browse everything at philotimorunningcoach.ca/blog. And if you want help building a comfortable, confident training plan, I’m always here.

Read the following blog about injury prevention:

How to Treat Chafing When It’s Too Late to Prevent It

Let’s imagine you ignored the warning signs. You wore the cotton shorts. You skipped the Body Glide. You said, “I’ll be fine,” with the confidence of someone who definitely would not be fine.

Now it hurts. A lot. Here’s how to fix it.

Start by cleaning the area gently with lukewarm water. Avoid hot water — this is not the moment to add drama. Pat the area dry, then apply a soothing product like petroleum jelly, zinc cream, aloe vera, or Aquaphor. The goal is to reduce friction, protect the skin, and keep the area clean.

Loose clothing is your new best friend while healing. Avoid running until the irritation fades. It’s better to take a day off than make a small problem much worse. Once healed, return to your prevention routine with renewed dedication.

Practical Tips for Runners

Chafing may not be glamorous, but staying comfortable on long runs makes a huge difference in performance and consistency. Prevention leads to confidence, and confidence leads to better training.

Here is your one bullet-point section for the second half:

• For smooth, pain-free running, choose moisture-wicking clothing, apply Body Glide or Squirrel’s Nut Butter on friction zones, rinse sweat and salt quickly after runs, and give irritated skin time to heal before jumping back into training.

Those simple habits will save you from many uncomfortable miles.

Final Thoughts

Chafing is one of those running problems no one likes to mention but almost everyone has experienced. It shows up unexpectedly, leaves a mark, and turns ordinary runs into unforgettable lessons.

The good news is that chafing is almost entirely preventable with the right gear, smart preparation, and consistent skin care. A little humor helps us talk about it, but proper prevention keeps it from happening again. And once you’ve dealt with it once, you’ll become a lifelong believer in Squirrel’s Nut Butter, Body Glide, and moisture-wicking clothing.

Running should feel smooth, strong, and enjoyable. With the right approach, your skin will feel the same.

Have you ever had chafing in an unexpected or funny place? Share your story or question if you’re comfortable — your experience might help another runner feel less alone.

If you want a personalized, chafe-free strategy for your marathon, half-marathon, or ultra training, I’m always happy to help.