I’m Training For My 13th Marathon And This Is My Favorite Marathon Workout

Woman running next to fence
(Image credit: JGI/Tom Grill / Getty Images)

The most important bit of any marathon training block is consistency. No single workout is going to make the difference to whether you achieve your goal time on race day—it’s the cumulative effect of months of regular running that makes the difference. 

That said, once you’ve run a few marathons, certain workouts stick in the mind as having proved great markers of your fitness as you approach the event, and for being enjoyable sessions overall.

I’m currently training for the London Marathon, which will be my 13th marathon and the 11th I’ve done with the same coach. While my coach always finds something fresh to tackle every training cycle, one workout that has been a regular feature of my build-up to races is a series of 3km reps at my target race pace broken up by a 1km float recovery.

I’ve done versions of this workout with five, six or seven 3km reps, so how many you do will depend on the overall amount you’re running and your experience. I usually do it two to three weeks before race day. 

The 3km reps are done at your goal race pace or slightly slower, and the floats are at a pace about 30 seconds per kilometer slower (48 seconds per mile slower, if using miles for your race pace). The floats shouldn’t feel tough, but they also shouldn’t be completely easy either. My top tip is to make sure you don’t run the floats early on in the workout too fast, that’s a recipe for disaster.

Depending on how many 3km reps you do, plus the distance of your warm up and cool down, the workout usually ends being 25-30km long, with a long stint running at your goal race pace. If you can knock out several 3km blocks at race pace with only float recoveries towards the end of a marathon training plan, it’s a great sign that you’ll be able to hold that pace on race day once you have tapered.

Finishing this workout feeling smooth and controlled is a massive confidence boost and in my experience it’s usually followed by a successful race. Conversely, if you do the workout and have to work hard to hold the pace during the 3km efforts, it could be a sign the pace is not quite there yet. Don’t despair if that is the case though, it could also be a sign that you didn’t sleep well that night, are a bit ill, or are just having a bad day.

It’s also a good workout for practicing your fueling strategy for the race, because you can road test carrying and using your gels and drinks while actually running at race pace for long periods. I usually fuel during the workout as if it’s the marathon itself, carrying everything I need for the full distance with me, even if I don’t plan to use it all.

This is a tough workout and one last thing I’d say about it is that it’s worth finding a flat, relatively clear loop to do it in, ideally without any traffic—a park loop is usually a good bet. Most marathons offer closed, flat roads and trying to hit the pace you plan to run in those conditions in training—while crossing busy roads and dodging pedestrians—is a lot harder.

Nick Harris-Fry
Senior writer

Nick Harris-Fry is a journalist who has been covering health and fitness since 2015. Nick is an avid runner, covering 70-110km a week, which gives him ample opportunity to test a wide range of running shoes and running gear. He is also the chief tester for fitness trackers and running watches, treadmills and exercise bikes, and workout headphones.