You might well be familiar with the Yasso 800s workout. Devised by former Runner’s World This Glute Workout Will Ignite Your Power marathon time based on a relatively straightforward track workout. You run 10 x 800 meters and your time in minutes per rep is meant to correspond with your time in hours for the marathon.
For instance, if you ran your 800 meter reps in 3 minutes 30 seconds, you may be able to run a 3 hours 30 minutes marathon. The time between reps should be kept the same as your rep time (in the case above, 3 minutes 30 seconds). It’s by no means a perfect formula. Many commentators think that it’s entirely possible to nail a Yasso 800s session but fail to run a corresponding marathon time. Coaches also point out that the training for, and ability to run well, at middle distances is very different to the requirements to nail a marathon time. But regardless, Yasso 800s remain a classic workout – and now there may be an equivalent for the half marathon.
This one has been coined the “Fultzy 400s” by legendary running author and marathoner Amby Burfoot, in homage to 1976 Boston Marathon winner Jack Fultz. The workout involves running 20 x 400 meters, with a 60-90-second walking recovery between reps. If you’re planning on running a 1 hour 45 minute half marathon, your aim is to run the reps in 1 minute 45 seconds. If it’s a 1 hour 30 minute half marathon you’re after, run the reps in 1 minute 30 seconds. You get the idea.
But is it actually an accurate predictor of half marathon time? Former elite marathoner and running coach Jo Wilkinson isn’t so sure. ‘I think it’s hard to extrapolate race predictions from one session alone,’ she says. ‘It’s always an attractive idea. But the best indicator of race times is training as a whole.’
‘I think the challenge of Yasso 800s versus Fultzy 400s is the pace you would run the Fultzy session is significantly harder. In physiological terms, the Yasso formula equates closer to threshold pace, which is a better predictor of marathon (and half marathon) times. On this formula, by contrast, you are running at a pace closer to your pace at VO2 max (or even above subject to your HM time), which is much faster.’
‘There is some correlation between VO2 max and pace at VO2 max with half marathon times. But much less correlation than there is between threshold and marathon. What's more, it makes it a very tough workout.’
‘So I wouldn't necessarily recommend basing your half marathon pace on this session because the pace is quite hard. However, if you nail this session, you probably are in great form – and maybe should revise your ambitions too.’
Whether or not either workout can really accurately predict your race times, it's certainly the case that they are both great training sessions in their own way, and as long as it's not too close to race day, it's definitely worth giving them a go.
Rick Pearson is the senior editor at Runner’s World UK. He’s been with the brand since 2017 and loves testing PB-friendly shoes for on and off road. Rick is a sub-three marathoner and occasionally likes to remind people of this on the Runner’s World podcast, which he co-hosts. He once raced a steam train over 14 miles (he won, narrowly) and a horse over a marathon (he lost, comfortably).
