How Much Harder Is It to Run a 15K vs. a 10K?

You can complete a 15K with a little more time and training.
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So, you've successfully completed a 6.2-mile, or 10K, race and now you're wondering whether you should tackle the next logical increment -- the 15K. A 15K race is 9.3 miles long, a respectable distance for any runner to undertake. Training for a 15K is definitely harder than training for a 10K; you are subjecting your body to even more impact and demanding that your lungs and tissues work hard for a longer period of time and over a greater distance. But, with a little more time and training than you needed for the 10K, you can work 15K training into your busy schedule and finish the race injury free.

Increased Impact and Training

    Longer distances are harder to run, and take more time to train for as you add distance slowly, week by week, to avoid overuse and injury. During a run, whether it's for training or during a race, you subject your body to repeated forces of impact. During a 15K, you can expect to subject your body 50 percent more impact, so you are stressing your joints for longer. This additional impact requires additional conditioning, so be prepared to go above and beyond what you did to prep for your 10K. Your cardiovascular system and your connective tissues will thank you on race day.

Longer Race, Slower Pace

    Predicting your 15K race pace isn't quite as easy as multiplying the pace you ran 10K by one and a half. The 15K should be run at a slightly slower pace than your last 10K was. For example, according to the McMillan running calculator, if you were able to finish a 10K in 58:05, a 9:21 minute per mile pace, your goal time for the 15K should be 1:30:00, a 9:39 minute per mile pace.

Train for 15K

    Remember the rule of specificity: You get what you train for. Don't just repeat your 10K training program and expect to tack on three extra miles on race day and get a satisfying finish. Adopt a training plan specific to 15K training, which is going to incorporate some longer runs than you got used to while you were training for your 10K. Hal Higdon recommends following a 10-week, 10-mile training program, since a 15K is only slightly shorter than that. With this program, expect to cross train and complete a long run of eight miles during the last training week before the week of the race.

Avoid injury

    You are undertaking a race that is 50 percent longer than a 10K. Remember to add distance slowly, or risk big time injury, says Dr. Joan Ullyot, author of "Women's Running." The 10 percent rule says that you should not increase your mileage by more than 10 percent in any given week, but with an overall distance increase of just about three miles, it shouldn't take you long to build up your mileage until you're ready for race day. A three mile increase to your current fitness level is easily and quickly achievable, with a little bit of 15K focused training.

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