One of the biggest discussions for endurance athletes is whether long slow distance work is of benefit or whether high intensity intervals give you more return for your limited time. Those who are searching quick returns (and trying to sell it to you) use terms such as ‘quality over quantity’ and ‘garbage yardage’ when referring to pointless slow miles. To be fair, it’s much easier to sell you a 12 week workout plan, which requires only 30 minutes a day, than to convince people to take the long term approach. Yet still, the world’s greatest distance runners do 100+ miles per week, much of it at a very slow pace. It hasn’t changed for the last 50 years. Clearly they don’t know what they’re doing.

So why is slow volume important?

For people racing Ironman, half marathon, marathon and ultra distance events, the aerobic threshold is the most important dictator of performance. Let’s put this in simple terms, the aerobic threshold is the point below which, you can hold a full conversation whilst exercising. Once you cross the aerobic threshold you switch from being able to hold a full conversation to a ‘broken conversation’.

So in simple terms, the higher your aerobic threshold, the faster you can run or cycle, whilst still holding a full conversation. In longer distance events, you can’t race at a high intensity, it’s physiologically impossible and it doesn’t matter how mentally tough you think you are.

You’ll run your marathon or ultra at conversation pace. So the question to ask is… ‘how fast is your conversation pace?’ At what speed are you able to run or cycle, before your breathing rate increases and you’re no longer able to hold a full conversation? Because that’s where the gains are for long distance events and that’s the single most important factor for performance, not your maximal output.

What we’re discussing here is ‘economy’ rather than ‘maximal’. How economical are you when moving at a slow to steady pace? How much fuel are you using? That’s what matters in longer distance events. Unsurprisingly, maximal intervals don’t really target that area, so maximal intervals are not the way forward to solve this particular issue and raise aerobic threshold.

Lydiard recognised this in the 1950’s and encouraged runners to do high volume at conversation pace. His plans are still evident today at the highest level. In 1989 when Mark Allen beat Dave Scott at the iconic Iron War in Kona (after blowing up several times trying), he went on to thank Philip Maffetone for his innovative training ideas, which was based on running below aerobic threshold to enhance economy and develop aerobic base… except it wasn’t innovative or new, it was the same thing as Lydiard but a different package.

If you look at elite training plans for endurance sports over the last 50 years, you’ll see the same themes throughout. High volume at an easy intensity (the bulk of it below aerobic threshold) mixed with small amounts of peak speed work. Then introduce high intensity work at the correct time of year. Lydiard did it in the 50s and recent research of elite athletes shows the same pattern.

So should I do high intensity interval work?

Yes, but only at the right time. Generally intervals enhance fitness for 6-10 weeks and you see rapid gains within that time, that’s why it’s easy to sell. The issue is, you then plateau and lose performance, so there’s no long term development. Phase them in, based on when your big events take place. Start doing intervals 8-10 weeks before your event (in moderate amounts) and it’ll give you the cherry on the cake. But you need to make a cake first.

GO HERE to read last week’s blog about training zones and how the aerobic threshold is used to help you set them.

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