Train easy for a 10K PB!

As a coach and a person who competes in triathlons and other endurance events, I have been interested in the work by Dr Phil Maffertone (2010) and Dr Stephen Seiler (2010, 2019) and a book written by Mark Sisson and Brad Kearns (2016). Very loosely, they all believe that the majority of your training should be completed in the easy, aerobic zone but the occasional hard session, which produce the performance gains, need to be really hard.

The Covid-19 pandemic spread across the world at the beginning of the year and I consciously made the decision to transfer my competition entries to 2021, as I believed it was unlikely mass participation events would happen in any great number during this year.

This got me thinking! I could use this time in lockdown to train consistently, making sure I stayed in my aerobic zone, using heart rate as an indicator. By training in this easy zone I was able to build a strong endurance base (engine) without the risk of injury and ‘burn-out’ that is associated with training too often in the anaerobic zone. After 4 months I decided to run 10K at race pace and repeat the same course 10 days later. To my amazement, having done only easy aerobic workouts, I ran my 1st 10K in a time that I would not have been ashamed of 20 years ago and the second 10K, a couple of days before my 57th birthday,  I knocked a further 5 mins off my time bringing me close to my all-time 10K PB. Furthermore, my recovery after the two time trials, was quick with little soreness or stiffness.

The take-home message here is to train easy most of the time, but the hard sessions need to be HARD, and don’t get sucked into the ‘black hole’ that most amateur athletes find themselves training in; the anaerobic threshold or even maximum intensity heart rate zones. Training in these zones for long periods of time will eventually lead to injury, illness and ‘burn-out’.


Maffetone, P. (2010) The big book of endurance training and racing. New York: Skyhorse Publishing.

Seiler, S. (2010) ‘What is best practice for training intensity and endurance distribution in endurance athletes?’ International Journal of Sports Physiology and Performance, 5, pp.276-291.

Seiler,S. (2019) How ‘normal people’ can train like the worlds best endurance athletes. Available at:

Sissons, M and Kearns, B. (2016) Primal Endurance. Oxnard, CA: Primal Blueprint Publishing.