From DNS to DNF, we’ve all heard (or experienced) some marathon horror stories. Injuries, a missing contact lens, heat exhaustion, blisters, crying in a porta-potty; you name it, this coach has heard or lived it. Most of these hazardous tales could have been avoided if woebegone marathoners had followed just two simple rules: Prepare, and nothing new on race day.

Say it with me, folks: nothing new on race day.

If a running coach set out to write a handbook on “how to suffer unnecessarily,” it would look a lot like the list below. Let’s walk through six ways you could ruin your marathon experience—and, of course, some practical tips for those aiming to run a strong, successful race.

Don’t Train!

This is a striking example of self-sabotage in marathon form, with a bold simplicity that is almost admirable.

Skipping training but still showing up on race day is like attempting surgery after watching a single video titled “organs explained in 7 minutes.” You are technically there, but in practice, everything quickly falls into chaos.

Running coaches often say a marathon is not simply 42.195 km on race day—it is the result of everything you’ve done beforehand. If that accumulated preparation is close to nothing, the race turns into a simple arithmetic problem with an unpleasant outcome.

To truly “respect the distance,” as experienced marathoners like to say, you need to invest time in proper training. This gives you the chance to build strength and understand your own needs for race day. Without preparing your body and systems for 26.2 miles, you significantly increase the risk of injury and serious physical breakdown, including conditions like rhabdomyolysis (often called “rhabdo”).

Run the Full Race Distance a Week Out

This one is especially popular among athletes who suddenly discover “confidence” in the final week.

The logic feels comforting: “If I can run 42 km now, I can do it on race day.” Unfortunately, the body disagrees loudly.

Sports science literature on tapering shows that performance improves when training load is reduced before endurance events. A widely cited review in the Journal of Sports Sciences notes that proper tapering can improve performance by 2 to 3 percent, largely due to muscle glycogen restoration, neuromuscular recovery, and reduced fatigue markers.

Now contrast that with running a full marathon a week before the actual marathon.

What happens instead:

Muscle damage is still repairing on race day Glycogen replenishment is incomplete Inflammatory markers are elevated your legs feel like they are borrowing energy from a future life

A running coach would describe this as “arriving at the start line already halfway through a bad day.”

There is also a psychological trap. You finish your practice marathon thinking you are prepared, but what you actually trained was exhaustion, not performance.

Wear the Wrong Gear

When race day comes, you might choose to wear that adorable crop top at the expo, or show support for your friend’s new landscaping business with the cotton T-shirt he gave you. If your aim is to make the race as uncomfortable as possible, prioritizing style over practicality is definitely the way to go.

By the way, check the forecast. If it’s warm, dress as if it’s 20 degrees warmer than the predicted high for race day. If it’s going to be chilly, bring gloves, ear warmers, and some throw-away gear to the start line (most races collect discarded clothing and donate it locally). Sunny? Don’t forget your hat, visor, or sunglasses.

If you wear contact lenses and are traveling to a race, pack a spare pair just in case. If you’re someone who tends to get blisters or chafing, apply anti-chafing balm generously—think of it as frosting a full-sized human cupcake—and make sure your socks are in good condition.

Choosing the right shoes and socks can make the difference between finishing strong or ending up in the medical tent with painful blisters. Opt for technical, moisture-wicking socks like merino blends, or for extra comfort, try toe socks to maximize foot support and reduce friction. Also, make sure to trim and file your toenails—but don’t cut them too short.

You also don’t want to run in either too old or brand new shoes. Get a few runs in them (and your race day socks!) before the big day to note any potential hotspots and give your feet a chance to acclimate to the new environment.

Go Out Way Too Fast

This is where optimism meets physics and loses badly.

At the start line, adrenaline is abundant, pacing discipline is fragile, and everyone suddenly believes they are in peak condition. The first 5 to 10 kilometers become a festival of unsustainable enthusiasm.

But human energy systems are brutally honest. The body relies on a mix of glycogen and fat oxidation, and when you exceed sustainable threshold early, glycogen depletion accelerates. Once glycogen runs low, fatigue arrives not as a suggestion but as a takeover.

Elite coaches often reference the concept of “positive splits prevention.” Even pacing is strongly correlated with better marathon performance. Studies analyzing major marathon datasets show that runners who maintain stable pacing are significantly more likely to achieve personal bests compared to those who start too fast and fade.

One practical way to support this pacing discipline is by using real-time physiological feedback rather than relying on excitement or perceived effort alone. This is where a heart rate monitor can be especially helpful during the early stages of the race. By tracking heart rate zones, runners can stay within a sustainable aerobic range, avoid unnecessary surges, and reduce the risk of burning through glycogen too quickly.

Devices like the Coospo heart rate monitor provide continuous and accurate heart rate data, helping runners maintain controlled effort from the very first kilometer to the final stretch. In a race where adrenaline often overrides judgment, objective data can help bring discipline back into the equation.

Don’t Eat or Drink

You feel nervous on race morning, so you drink your coffee and figure it’s too early to eat. Hydration? You skip it—no interest in dealing with porta-potty lines. As for gels, gummies, or electrolytes?

To be clear, “the wall” isn’t a literal wall of bricks and mortar—it’s the result of skipped hydration stops and that extra gel you decided not to pack because you were sure you wouldn’t need it. That heavy, slogging feeling—like running through mud with cinder blocks for feet—kicks in when your body runs out of glycogen, its primary fuel source for high-intensity exercise.

Proper fueling and hydration involve both drinking enough fluids and loading up on carbohydrates in the days leading up to the race, as well as maintaining sufficient carb intake throughout the marathon. While running, target approximately 60–90 grams of carbohydrates per hour through options like energy gels, chews, or sports drinks. It may seem like a high amount, but current research supports this approach.