What Are Running Splits? Here's How to Use Yours for Better, Faster Runs

Do you find yourself sprinting the first mile of your long, "slow" runs? Or maybe you're training to hit a certain race time? Either way, tracking your running splits is the key to better pacing and stronger finishes.

A running split is the amount of time it takes you to run a certain distance or section of a race. For example, if you run a 5K, you could break the run up into mile- or kilometer-long splits.

By keeping an eye on your split times, you can see how you're pacing, explains Ellie Somers, DPT, a physical therapist, running coach and owner of Sisu Performance and Physical Therapy in Seattle.

Do you need to pick things up? Or slow your roll? Trying to run consistent split times (or negative splits, which we'll explain below) can help you run your best.

Splits can be seconds or minutes in length, and they generally measure how fast you run a certain number of miles or kilometers.

For instance, if you run a lap around the track, you could break it into 100-meter splits, and each split time will be a matter of seconds. If you run a 5K, however many minutes it took you to run a mile — or kilometer — can be a split.

For U.S. women, the average 5K time per mile is about 13 minutes, 21 seconds. Here's how this could break down into consistent mile splits:

Want another running split example? According to running statistics, the average marathon pace is 6 minutes, 43 seconds per kilometer for men. A marathon is 42.2 kilometers long, so here's what consistent 5K splits would look like at this pace:

In most cases, runners track their splits with running watches or apps. Most any running watch with GPS will automatically track your splits. If yours doesn't, it likely has a split button you can press at the end of each lap on the track or mile marker on the trail.

What's more, different run trackers like FitBit and MapMyRun have buttons or functions to let you "make" the split, and most devices can synch to your phone to give you more info. On screen, you can typically see how your splits vary from one another.

Also, when you're running, many smart watches display your current mile time as well as your average mile time for the whole period you've been running. That way, if you see your current mile is pacing to be a lot faster or slower than your previous miles, you know you need to adjust your running speed. You can set many watches and apps to alert you with your split time at the end of each mile.

Tracking your running splits can be a helpful way to keep tabs on your pacing and even see how it improves over time, Somers says. Split times in running can also reveal areas for improvement — like sprinting (and tuckering yourself out) right out the gate.

A negative split is when, during a specific run or workout, each split time is shorter than the one before. So, during that marathon, you're running each mile faster than than the last. In a positive split, you run each mile or kilometer at a slower pace.

Coaches usually encourage runners to aim for negative splits.

"When someone can execute negative splits well, it's a great sign that they're homing in on good pacing and pace control," Somers says. "When you know enough about your body to be able to save a little bit for the end while still moving on tired legs, that's proof of hard work."

The idea negative split depends on your goals, experience and the run you're doing. But, generally, with negative splits, each time should be about 5 to 30 seconds shorter than the last, she says. While a marathoner might try to take 5 or 10 seconds off their pace each mile to get down to their ultimate goal finishing pace, a 10K racer might try to shave off 20 or 30 seconds from each mile.

Large negative running splits generally are part of aggressive racing strategies, and most common in shorter distances. Again, every athlete (and race or effort) has a different strategy.

To achieve negative splits, think of your effort in terms of rate of perceived exertion, or RPE, recommend Somers. Start your run at a lower RPE and increase it gradually with each split.

"Perceived exertion is one of the most important variables when working a program," she says. "You have to trust your feelings and your training. Usually by the time you're finishing with a negative split, your perceived exertion will be much higher than when you started and were getting your body warm."

So what about positive splits? These happen when each mile is slower than the last and are very common in new runners who are new to pacing or start off their runs too fast and tire out quickly.

And sometimes, splits can be all over the place. That could be part of getting used to running or simply doing a less-structured workout. For example if you're running to the next tree and then walking for a while, your split times could all be radically different. That's OK!

It's normal to wonder what a "good" split time is for something like a mile, 5K, half-marathon or marathon distance.

"It's going to be different for each runner," Somers says. While one marathoner may hit their goal striding along like rhythmic metronome, another may lean into a different strategy.

In the end, the best running split is the one that feels right for you.