John Davis

Written by John Davis


How to Stop Chafing, Blisters, and GI Stress Ruining Your Race Day

Blisters, chafing, and stomach upsets (GI Issues) can quickly turn a great race into a death march. Learn about the latest research to prevent them, to make sure your race goes smoothly (if you run smart!).You know the feeling.

You were ready to run fast, you started the race (or workout) feeling great, and you knew in your heart that this was going to be the race you have been waiting for.

Suddenly, disaster strikes. You get that sinking feeling in the pit of your stomach that things are about to turn from bad to worse. You prepared so well. You got in all the training you needed, and now its all going to come crashing down because of a minor body issue.

We have all been there.

Blisters. Chafing. Gastrointestinal Issues. Fluke race day injuries.

They can stop anyone in their tracks, and make dropping out seem very tempting (or inevitable!).

In this post, we are going to focus on avoiding the miscellaneous annoyances and bothers that can come up at just the wrong time and turn a great race into a miserable death march within a matter of minutes.

While there’s a host of folk remedies on how to avoid issues like chafing, blisters, GI problems, and race-day injuries, recently some doctors and researchers have turned their attention to these issues as well.

The surge in recreational marathoning has brought about renewed attention from the scientific community on everything from “jogger’s nipple” to bloody stool after races.

In this article, we’re going to examine some of that science to provide you with the most “scientifically proven” solutions.

The Science of Blisters and Chafing

One of the first revelations we’ll see is that “minor” issues like blisters and chafing can be anything but mild annoyances.

A study conducted by William Roberts, the medical director for the Twin Cities Marathon, reviewed and classified the reasons for runners visited the medical tent at the TCM during the twelve races between 1983 and 1994.1

On average, 25 out of every 1000 finishers had to visit the medical tent post-race. Of these “medical encounters,” 21% were skin conditions like blistering and chafing!

The majority of visits, 59%, were exercise-induced collapse, while a comparatively small 17% were what we would actually term “running injuries”—musculoskeletal problems.

A more recent review of runners in need of medical attention at a large Wisconsin road race series was published in 2008 by Richard Nguyen and colleagues.2  Their research, which examined a multi-day event which included a 5k, a marathon, and a four-person marathon relay, found a lower incidence of skin injuries (11%) but nearly the same incidence of musculoskeletal problems (18%).

I would wager that the lower incidence of skin problems was due to many of the runners—the 5k and marathon relay participants—running much shorter than the participants in Roberts’ study, all of whom finished a full marathon

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Cause and treatment of blisters and chafing

Skin issues in marathoners were tackled head-on in a review paper authored in 2012 by Matthew Helm et al. at SUNY-Buffalo, which took an in-depth look at the cause and treatment of the various skin ailments that can send runners to the medical tent.3

Here’s the deal:

Broadly, their findings highlight the importance of well-fitting shoes (that have been worn at least a few times before race day, but are not too old either!) and controlling moisture: the authors report that wet conditions and “non-technical” clothing (i.e. cotton shirts and socks) are associated with developing blisters and chafing.

When water gets trapped between your skin and your clothing or footwear, it can dramatically increase friction.  This can be not only painful, but also leads to infection.

Though technical shirt/singlets and ultra-thin synthetic running socks are usually associated with being a “serious runner,” sponsorship isn’t the only reason elite athletes are wearing polyester, nylon, and spandex running gear.

As most runners know, Helm writes that areas prone to blistering and chafing (under your arms, for example) can be protected with petroleum jelly or “blister patches.”

[bctt tweet=”I HATE blisters & chafing. If you do too, use this guide to make sure it never happens again!”]

Race Day Injuries

Blistering and chafing aren’t the only things that can wreck your race or send you to the medical tent.

A 2006 study published by Leon Sanchez and his coworkers at Beth Israel Deaconess Medical Center in Boston examined race-day musculoskeletal injuries and gastrointestinal tract (GI) issues in marathon runners.4

Reviewing several other papers which examine race-day running injuries (including Roberts’ TCM study), Sanchez et al. present some important findings.

First, more participants in a marathon suffer injuries than in shorter races.  This should come as no surprise, given the extreme length of the marathon.

Second, knee injuries are the most common race day issue in road racing (interestingly, ankle injuries are dominant at track meets).

Finally, and perhaps most relevant to our interests, there is an inverse relationship between miles run in training and propensity to suffer an injury on race day.

The better-prepared you are for the race, the less likely it is that you’ll become injured during the race. This makes intuitive sense, but stands out against other research that shows that higher mileage runners suffer more injuries in training.

The Science of GI Issues

With respect to GI problems, Sanchez et al. report that the bowel issues all too familiar to long distance runners are a result of decreased blood flow to the gut during an intense effort.

The proportion of runners who have bloody stool after races varies wildly among different studies, but the trend is upwards with increased race distance, presumably due to the increased stress associated with longer races.

Check this out:

For unknown reasons, GI issues are more common in women than men.

Unfortunately, Sanchez et al. don’t comment on any possible causes.  They do, however, recommend runners avoid anti-inflammatory drugs like Advil and Aleve before races, as they are associated with lower intestinal bleeding.

A much older study by Emmett Keeffe et al. suggests that dietary factors may play a role in GI irritation,5 but there aren’t any clear answers—this is an under-explored area in need of future research.  Until we know more, experiment and find out what works best for you.

Our Recommendations

Preparing for your target race is only half the battle.

Even once you’ve gotten to the starting line fit and healthy, you also need to ensure that you’re ready to cover the distance without being slowed by blisters, chafing, race-day injuries, or GI trouble.

Fortunately, keeping in mind some basic principles, this shouldn’t be too hard.

  • Avoid skin irritation by wearing shoes in good condition that you’ve tested out on a few long runs prior to the race, wear “technical” clothing and snug-fitting socks made from synthetic fabric, and protect chafe- or blister-prone areas with petroleum jelly, a band-aid, or blister patch.
  • Make sure you prepare in the weeks and months before the race to lower your risk of a race-day injury (keeping in mind the course: don’t neglect hills in training if you’re running the Boston Marathon!), and experiment with what you eat and when to dodge GI irritation.

While there’s always an element of chance on race day, and you’ll never be able to guarantee a trouble-free race, good preparation often seems to bring good luck!

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1. Roberts, W. O., A 12-yr profile of medical injury and illness for the Twin Cities Marathon. Medicine & Science in Sports & Exercise 2000, 32 (9), 1549-1555.
2. Nguyen, R. B.; Milsten, A. M.; Cushman, J. T., Injury Patterns and Levels of Care at a Marathon. Prehospital and Disaster Medicine 2008, 23 (6), 519-525.
3. Helm, M. F.; Helm, T. N.; Bergfeld, W. F., Skin problems in the long-distance runner 2500 years after the Battle of Marathon. International Journal of Dermatology 2012, 51, 263-270.
4. Sanchez, L. D.; Corwell, B.; Berkoff, D., Medical problems of marathon runners. The American Journal of Emergency Medicine 2006, 24 (5), 608-615.
5. Keeffe, E. B.; Lowe, D. K.; Goss, R.; Wayne, R., Gastrointestinal symptoms of marathon runners. The Western Journal of Medicine 1984, 141, 481-484.

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3 Responses on “How to Stop Chafing, Blisters, and GI Stress Ruining Your Race Day

  1. For the love of country leave the cotton socks at home when you run. When it comes to socks go with synthetic blends. I prefer Belaga and Drymax brands.
    If extra protection is needed opt for one of the newer generation anti chaffing and blister products available. Vaseline is awful. My favorite is Skin Strong products, especially Slather. Popular with triathletes I have found it excellent for both trail and road running to prevent blisters.
    The undisputed King of Feet is John Vonhof. His book, “Fixing Your Feet” is the runner’s bible for all things about keeping your feet healthy and happy. Check out the website for more info:
    Good fitting shoes, quality socks and keeping hydrated will go a very long way in preventing blisters.

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