Whether you’re gunning for a new 5K personal best or tackling your next 10K, 400m repeats are a classic workout that you’ve likely seen in your training plan. On paper, it doesn’t look very tough–10-12 x 400m at 5K race pace–but many runners are surprised when they have a hard time completing it.
This staple session is a tried-and-true strategy to help bring down your 5K or 10K time, so use these tips to avoid common pitfalls that can make this workout go sideways.
5K race pace feels quick during a race, but over 400m, it may feel quite slow, especially during the first two or three repeats. For this reason, many runners make the mistake of going out faster than race pace at the beginning, only to crash and burn in the back half of the workout. The goal of this session is to run at the correct pace, so that you’re prepared for the physical and mental challenge that will inevitably rear your head in the last few intervals. This will mimic the last kilometer or two of your race, and prepare you to push through that challenge.
know what to expect
If this is your first time tackling a workout like this, don’t be surprised if you struggle with it. As we already mentioned, it is deceptively difficult, so if you have trouble hitting your goal pace during the last few intervals, don’t panic. Do your best to stay calm and get to the end of the workout–you may need to try it a few times before you ace it.
Play with the rest
You can shorten or lengthen the recovery intervals, but avoid shortening your rest just for the sake of making the workout harder. Ideally, you should choose a rest interval that is long enough to allow you to continue hitting your goal pace, and then keep that time the same throughout the workout. If you’ve done this workout a few times and are looking for ways to change it up or increase the challenge, try breaking it up into sets. For example:
(400m/1 min rest/400m/2 min rest) x 5–6
Don’t overdo it
It may be tempting to do this workout over and over again, especially if you struggled with it the first time around. We recommend including this session no more than twice in your race build-up: once near the beginning of your training block, and again four to six weeks later (but not less than one week before your race) to see how you’ve progressed . There are many other beneficial workouts to include in a 5K or 10K training plan, and when you do the same workout too often, you run the risk of getting into a rut.
If you haven’t tried this workout before, start with this formula and adjust the rest intervals as needed.
Warmup: 10-15 minutes easy jog, followed by mobility drills and strides.
Workout: 10-12 x 400m at 5K race pace, with 2 minutes rest or 300m-400m easy jog between reps.
Road option: 10-12 x 2 min with 2 min easy jog between intervals.
Cooldown: 10-15 minutes easy jog followed by light stretching.