Training for a Marathon

Mar 20, 2014

Fitness Handout

Whether you want to run a marathon for the thrill of it, to cross it off your bucket list or to qualify for the prestigious Boston Marathon, it all starts with a single step. When you put together enough steps to cover 26.2 miles, you become a marathoner!

So how do you run a marathon? Jason Karp, PhD, the 2011 IDEA Personal Trainer of the Year and author of Running a Marathon for Dummies, gives you strategies below.


Training for a marathon isn’t just about one long run each week—it’s about the total amount of running you do. To finish a marathon, you need to become as aerobically developed as possible.

Many novice runners don’t run enough miles during the week to support a long run on the weekend. You don’t want to run 4 or 5 miles on 2 or 3 week days and then shock your legs with a 15-miler on Sunday. You may be able to get away with that once, but if you do that every week, you’re setting yourself up for injury.

Long Runs

To avoid injury, the long run shouldn’t be more than about a third of the total weekly mileage. So, if you’re planning a 20-mile long run, you should be running at least 60 miles per week. Most people training for a marathon don’t run that much, so circumvent the problem of making the long run a large percentage of the weekly total by trying a midweek, medium-long run that is about 65%–75% of the length of your long run.

Lengthen the long run a mile at a time for 3 or 4 weeks (even running the same distance a few times) before backing off for a recovery week. Keep adding miles until you reach 20–22 (or 31⁄2 hours, whichever comes first), and do your longest run 2–3 weeks before the marathon. The amount of time you spend on your feet is more important than the number of miles you run.

If you have run a marathon before and are training to improve your finish times, you need a different strategy: Alternate long runs with a medium-long run (12–16 miles) that combines long-slow-distance (LSD) running with segments at acidosis threshold (AT) pace (Karp 2012). AT pace is a comfortably hard aerobic pace, about 15–20 seconds per mile slower than your current 5K race pace or near your current 10K race pace. These LSD/AT combo runs simulate the physiological and psychological fatigue of the marathon.


After months of training, you’re ready to taper your training so you are fresh for race day. To maintain fitness during the taper, maintain intensity with AT runs and VO2max intervals while reducing the running volume. (Interval training near the speed that triggers VO2max can help you run faster.) If you taper for 2 weeks (best for beginner runners), reduce your peak weekly mileage by 30% the first week and 60% the second week. For a 3-week taper (best for intermediate and advanced runners who have been running more than 50 miles per week), reduce your peak weekly mileage by 30% the first week, 50% the second week and 65% the third week (Karp 2012).


Karp, J.R. 2012. Running a Marathon for Dummies. Hoboken, NJ: Wiley.

IDEA Fitness Journal, Volume 11, Issue 4

© 2014 by IDEA Health & Fitness Inc. All rights reserved. Reproduction without permission is strictly prohibited.


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