JSET is an unconventional training method

(and it works)
Running a fast marathon is simpler than most training plans make it seem. While there is good training value to be found in sessions run at a pre-prescribed pace I suggest that there is equal training value, and more enjoyment, to be found in running however you enjoy. That might be run-commuting, pacing a friend, long runs or anything else. But as long as the total training load is high enough then you can train for your marathon in pretty much whatever style you like. JSET does not prescribe sessions, instead I give you a training load target each week. Every mile you run moves you towards this training load target, with faster running counting more for more training load.
As an example of how JSET works, imagine an runner aiming for a 3 hour marathon. While many people aim for a sub3 time each year (and all to often don't make it) I claim this result is achievable for almost any runner. One way of getting into sub3 shape is to train as described in the table below. Other than Saturday, all of the running is done at 5:00min/km.
Mon-Fri Sat Sun
7.5km before work & 10km at lunchtime 5km in 19min 17.5km (anytime of day)
The science says that by averaging this every week, you'll be in 3h shape. Of course, this is just one example of how a runner might train, there's an infinite number of other ways to structure this training load. The point is that training shouldn't be complicated - it's just running. However, there’s more than one way to skin a cat, and there’s more than one way to train for a marathon. So, if you want train in a more traditional way, that’s fine. JSET is a great tool nonetheless. It’ll tell you exactly what training load your body has experienced each week, and how much training you need to achieve your goal.

How does JSET actually work?

Here's a quick overview of the process, from today until race day.

Common questions about JSET

How far do I have to run? How accurate is JSET? How fast do I need to run? Find out below.

How accurate is JSET?

The original equation that JSET is based on claimed to be able to predict marathon performance to within 4min, only by knowing average weekly distance and average pace over the eight weeks before a race. However, this used data from a relatively small group of runners. In reality I've found the original equation has a consistent offset. For me it's -14min (I can always run 14min faster than the original equation predicts). For another JSET runner it's +10min (He's always 10min slower than the original equation predicts). Once you know your offset then you can use JSET to predict with exceptionally high accuracy. Most the time your offset can be calculated by looking at your training data over the last few years.

Does JSET account for cross training and hill running?

Cross training will probably help you run a faster marathon. But there is not enough data to know exactly how much faster a cycling / swimming / yoga session will make you. For this reason JSET only accounts for running training. The same goes for running on hills. Hills probably help but we don't know exactly how helpful they are.

How often should I train?

That depends on your goal. If you're aiming for a 3h30min marathon you might only need to run 4 times per week, but if you're aiming for 2h30min you'll need to run every day. The training ring makes it easy to know how much you should be running. Once you've met your training load target each week, put your feet up. Until then, go out for a run.

I've got a busy life. Will this work for me?

Absolutely! There are numerous way to fit running into a busy life. If it's possible you might want to consider a run-commute. Many people go for a few miles at lunchtime. These are just two example of easy ways to rack up the miles without using too much time from your non-running life.

What race times does it work for?

The equation was originally designed for people completing the marathon between 2h45min and 3h30min, but I have found it works just as well up to 2h28min. If you're looking to run slower than 3h30min, the equation becomes slightly less accurate (because lifestyle factors play a bigger role in your training) but the principal still works.