The key to running faster? Slow down…

I’ve had more amazing support this week in the form of some hefty sponsorship donations to the Lord’s Taverners, some lovely comments and conversations on both social media and in real-life, and some company on some of my runs this week, which was fantastic.  With running so many miles, training for Marathon des Sables, it has the potential to become quite lonely.  I do appreciate the solitude and meditative nature of running on my own, but it is also enjoyable to have someone to talk to.  So if anyone would like to join me on any of my runs I would love to have you for company, and to run at whatever speed is comfortable for you.  Now excuse me, while I get a bit nerdy…

Inspired by Rich Roll’s book Finding Ultra where he talks about slowing down your training runs to build aerobic fitness, I have been experimenting with heart rate zone training.  The theory goes something like this:  There are two main energy systems used when running.  The aerobic system is responsible for the generation of about 95% of the energy used in endurance sports.  Your anaerobic system is the system that you use when you can’t get enough oxygen.  It’s the system you use when you run fast and build up an oxygen debt.  It’s main fuel source is glycogen, the sugar stored in your muscles of which there is a finite supply, which is said to last for about 90 minutes.  Whereas the aerobic system burns fat, and there is a never-ending supply of that.  It is the ‘run-forever’ fuel source.  So when you run for long periods, you want to be using the aerobic system, not the anaerobic system.  You want to be burning fat and not glycogen.

You can build your aerobic capability and this is supposed to have two benefits: it trains your muscles to get used to burning fat.  It is said that this means you are less likely to ‘hit the wall’ as you shift to fat-burning once your glycogen stores are empty.  The second benefit is that it is supposed to enable you to run faster for the same effort, that is, at the same heart rate.  In order to achieve this you must train only in your aerobic heart rate zone, and not engage your anaerobic system.  There are various different ways to calculate heart rate zones varying from very scientific lactate tolerance threshold blood-tests to ‘woo’ equations involving your age and arbitrary numbers.  I’ve tried to be as scientific as possible, following Dr. Phil Maffetone’s methods, and determined that my heart rate zones are as follows:

  • Zone 4:  180-188 beats per minute
  • Zone 3:  161-180 beats per minute
  • Zone 2:  148-161 beats per minute
  • Zone 1:  134-148 beats per minute

So I’ve been running, and occasionally walking, to maintain my heart rate in zone 2 while training.  The theory is that I will be able to complete a whole run in zone 2 without walking at all eventually, and that in due course I will be able to run faster and faster while keeping my heart rate in zone 2, without ever troubling my anaerobic system.

The upshot to all of this is that I’m not running very fast, so if you want to join me, you’d be very welcome.

This week has been a ‘step-back’ week.  As I described in my previous post, ‘So how do you train for 6 back-to-back marathons across the Sahara Desert?’, I am gradually building up my mileage by around 10% per week.  But every three weeks or so I do a step-back week, where I do slightly less total mileage and shorten my longest run.  There are probably very good physiological reasons for doing this, but for me, the main benefits are mental.  It feels like you’re doing an easy week and this provides a welcome break prior to resuming the mileage-building next week.  So 37 miles in total this week with a 14 mile long run, before an intended 45 mile week next week, which will also be the furthest I will have ever run in one week!  As ever, if you haven’t already, your sponsorship, however great or small, would be very welcome at

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