Whether you’re a beginner or an experienced runner, after you’ve been training for a race for weeks or even months, and the day is finally here, you are pumped.

But if you start your race even a minute faster than your training runs, you may be setting yourself up for disaster, according to Jeff Horowitz, a Washington running, cycling and triathlon coach.

By starting out too fast, you risk burning through your fuel stores too rapidly, leading to bonking, or hitting a wall, later on, said Horowitz, who has finished more than 175 marathons and ultramarathons.

This is most obvious in a marathon, where energy conservation is crucial, but applies even in a shorter race. When you start out too fast, you may also risk injury if you’re not already warmed up sufficiently, he said. “It’s easy to lose track of how fast you’re going.”

So how do you know how fast you’re running?

You incorporate timed runs into your training. In a timed run, you try to cover a certain distance in a given amount of time rather than simply running the distance without regard to speed.

Even if most of your training is focused on adding mileage to your runs, timed runs are an important way to optimize your conditioning, Horowitz said.

In a distance run, the goal is to hit a certain number of miles, and it doesn’t matter how long it takes you to get there.

Timed runs can be mentally easier than distance runs because you know how long you’re going to be out there and can relax and settle in, Horowitz said. “For athletes who tend to get injured, timed runs are great because you’re not beating yourself up more than you have to.”

They’re also good for first-time marathoners who want to get acclimated to running four or more hours.

But timed runs are also critical in helping you improve as a runner overall by incorporating speed work and heightening your sense of speed so that you are better able to monitor your speed during your race.

“Time is crucial in speed work,” Horowitz said. “People who have a timed goal naturally get faster, and as you get more conditioned you become more efficient in how you process oxygen, and your muscles get stronger.”

Basically, you improve as a runner, making running all the more enjoyable.

For Hugo Rodriguez, a U.S. Foreign Service officer serving in Mexico City, timed runs are an essential part of training.“My favorite timed run is 9 minutes hard, 1 minute easy, then 8 hard, 1 easy, 7 hard, 1 easy, etc., down to 1 hard and 1 easy. The 9, 8, and 7 are at marathon pace; 6, 5, and 4 minutes are at my half marathon pace; and 3, 2, and 1 are all at a sprint pace,” he said.

“Timed runs are brutal, and when I see them on my schedule, I know it’s going to hurt,” said Rodriguez, who’s been running marathons and ultras for 25 years. “But I love the variability and feel great after the workout.” Rodriguez recently finished the NYC Marathon, his third marathon this year.

Horowitz likes to incorporate timed runs, especially repeats, into his runners’ schedules, because they give you a sense of what it feels like to run at different speeds.

“When you’re driving a car, you don’t always stare at your speedometer, but since you have experience driving at different speeds, you use cues, such as how fast the trees are going by, to know how fast you’re going,” Horowitz said.

In running, you can use your breathing or your sense of burn as cues to know how fast you’re going.

If you’re doing 800-meter repeats at an 8-minute-mile pace, you get a sense of what an 8-minute pace feels like and can begin to develop different gears as you run. Elite runners use these “gears” to calibrate their runs, Horowitz said.

From your timed runs, you will have built up a library of speed sensation. For example, as you run, you can tell yourself, “In my experience this is probably a 7-minute mile pace.”

There are multiple ways to do repeats — running a certain distance in repeat sets. A beginner runner can do eight 400-meter repeats at a 2:15 pace with a two-minute recovery period between them. The idea is that repeated high-intensity sessions of training with short recovery periods trigger an adaptation response to train the body to run at higher speeds.

Everyone has to do speed work to improve, Horowitz said.

“It’s not that you shouldn’t run faster in a race than usual,” Horowitz said. “You can take a calculated risk as long as it’s purposeful. If you know what it feels like to run at a particular pace, you can say to yourself, ‘I’m going to take a risk because I feel good today.’ ”

And timed runs teach you how to surge, Rodriguez said. “I’m good at holding my marathon pace at the beginning of the race, but as I get deeper, I tend to slow down.”

During the NYC Marathon, Rodriguez used a two-minute surge to get himself back to his marathon pace as he slowed down around mile 18.

“The timed workouts help me get comfortable with pushing myself hard and with that feeling where you push your pace beyond your normal capacity. The timed runs get me to use different muscles, too, which seems to minimize cramping.”

And while timed runs physiologically improve the explosiveness of muscle fibers without all the damage of running as far as you can as fast as you can, Horowitz said, they also keep running interesting.

Rodriguez looks for every opportunity to improve as a runner so that he can continue to do marathons.

“It would get boring doing the same workouts, and my timed runs change it up,” he said.

Carolee Belkin Walker is a federal bureaucrat, blogger and freelancer. She shares her fitness adventures on her blog, www.bethedog.ninja. The views expressed here are those of Walker and not those of the U.S. government.