This Workout Predicts Whether You’re on Track to Meet Your Marathon Goal. Here’s How (and When) to Try It Before Race Day.

As a marathoner with a specific goal finish time in mind, you have to walk the line between going out too fast on race day and maintaining a pace that’s fast enough to achieve your goal time. In the weeks leading up to race day, it helps to have a prediction of whether or not you’re on track to handle your marathon pace so you know you’re capable of leaving your best effort on the course.Many runners turn to Yasso 800s in hopes of predicting their marathon time. Bart Yasso and Amby Burfoot, former Runner’s World editors, believed the time of your 800-meter repeats in minutes and seconds equates to the time in hours and minutes of your marathon. (For example, running 800 meters in 3:30 meant you could run a marathon in 3:30:00.)While it’s a solid speed workout, and can give you some insight into your pace, there’s a better workout option one run coach swears by for his clients, helping them predict how fast (or slow) they should go on marathon day.You can perform this workout about three weeks before race day to get the data and have the confidence you need to set and run a realistic goal time. Here’s what to know.The Best Workout to Predict Marathon TimeThe best way to know if you’re going to be able to run your marathon race pace for 26.2 miles is to actually test your marathon pace in a long run, explains Brant Stachel, USATF-certified endurance coach at Fast and Free Performance Coaching. Doing this right after peak week of marathon training gives you an idea of whether you can hold the pace or if you need to reassess.The goal with doing this workout just a few weeks before marathon race day, Stachel says, is to finish feeling like you could manage that pace for a few more hours. If you feel that way, you’re probably in the right effort range for your marathon, especially because you have performed this run on tired, untapered legs, he says.A good rule of thumb for keeping steady at marathon effort is to stick to about a 5 or 6 on a scale of 1 to 10 for rate of perceived exertion (RPE), with 10 being all-out effort. That means you should be able to say a sentence or two for most of the effort, but not hold a whole conversation.The most important aspect of this workout is to focus on effort, not necessarily pace, Stachel emphasizes. Oftentimes, runners feel tempted to try and run a specific pace and see a perfect goal time for each mile, but in reality, your times vary based on factors like terrain, weather, and late-race fatigue. That’s why this workout is time-based rather than distance-based, so all runners can apply it to their training regardless of fitness level or pace.Why it works: This workout is long enough that you get to test pacing control and fueling, but it’s not so long that you can’t recover from it before you hit the starting line, Stachel says. “So I find that it’s a sweet spot,” he adds.How to do it:1. Warm up for 20 to 30 minutes at an easy pace2. 90 to 100 minutes at marathon effort (about 5 RPE)3. Cool down for 20 to 30 minutes at an easy paceYou can also add a slightly shorter version of this workout to the very beginning of your marathon build, Stachel adds, so you get an idea of where your current fitness level is at the start and end of training.For example, you can do 60 to 70 minutes at marathon effort about two to four weeks into your build as part of your weekend long run. “We want to know where you’re at in the beginning so we get a tentative training range,” he says. “Then we’re dialing that in ahead of time.”You don’t have to go into your marathon leaving your performance all up to chance. Stay focused on what you’re capable of doing, and let the excitement of race day and the energy of the crowds help carry you through to the finish line.Kristine Kearns, a writer and avid runner, joined Runner’s World and Bicycling in July 2024. She previously coached high school girls cross country and currently competes in seasonal races, with more than six years of distance training and an affinity for weightlifting. You can find her wearing purple, baking cupcakes, and visiting her local farmers market.