by Martin J. Trout

One of the most common questions that I get asked, predictably I guess, is:

“How should I train for trail races”?

The simple answer is basically the same as you would for any other running race but don’t forget to include hills, both up and down, and get prepared for some gnarly and unpredictable terrain under your feet. Of course it’s not quite as simple as that.

Volume and Intensity

There are two basic variables in running:

1) “Volume” – how FAR you run. The distance of each run multiplied by the frequency.

2) “Intensity” – how HARD you run.

Clearly both of these factors can have huge variables.

Elite Athletes Vs. Weekend Warriors

We have all heard of those amazing athletes who run 100-150 kilometres a week, divided between anything from 10 to 15 runs, and at the same time we have gazed in awe as a lithe gazelle speeds past us at what seems like warp speed.

Us, we plod through our 40-60 kilometres in a good week and maybe throw in a couple of faster sprints every now and then for the sake of good form. And that is why the first runners arrive at the finish line, have a shower, drink, eat and are long gone by the time we finally cross the line ourselves. But, considering the constraints on our precious time and our unfortunate choice of not so genetically favoured parents, how can we actually improve our performance.

It is probably not feasible, nor even advisable, for the majority of us to increase our running volume to elite levels. That is a one way street to injury, and probably not so great for our family or career choices either.

The Risk of Intensity Blindness

The solution adopted by many “weekend warriors” is that of increasing intensity (running faster). Sounds good – run faster in every training session and you will run faster in races.

Unfortunately what happens is that the athlete tries to run faster every day but his organism doesn’t have the time to recover and becomes progressively more and more beaten up and exhausted.

Instead of training at high intensity, which is where the real advantages lie, he or she tends to fall into a black hole of mediocrely high intensity (this is also due to the existence of “intensity blindness” as shown in a 1993 study at Arizona State University *(1)), sufficiently intense to tire out the organism but not intense enough to produce significant improvements.

It can probably work in the short term but in the long term it is a recipe for overtraining, injury and burnout.

The Risk of Intensity Blindness
The Risk of Intensity Blindness

Searching For Balance – “The Lydiard Boys”

So where is the “Cinderella Zone”? That seemingly perfect mix between reasonably paced, aerobic building volume and performance boosting intensity. Coaches and athletes have been asking this question for decades.

One of the earliest coaches to strongly differentiate his athlete’s training protocols was Arthur Lydiard who devised a system where the majority of training was done at an extremely slow, for elite standards, pace and only a small proportion of training was carried out with intensity. This differentiation was also periodised in such a way that lower paced running was carried out at the beginning of the training cycle, while faster, more intense running was done closer to the race event.

The world took note during the 1960, 1964 and 1968 Olympics where the “Lydiard boys” showed their worth.

This led to a proliferation of Lydiard style training programs, but there was no clear agreement on the correct amount of easy volume and hard intensity, nor even where the exact levels of what should be considered easy or hard were. It was more or less left to the individual coach or athlete, to work it out for themselves.

The Origins of Polarised Training

In a 2004 study in Norway *(2), researchers looked at how elite athletes were dividing their training time.

They found that these top level cross country skiers were spending approximately:

  • 75% of their training time doing low intensity high volume work (below Aerobic Threshold)
  • 15-20% dominated by periods of high-intensity work, such as interval training.
  • 5-10% at paces in between which could be described as moderate intensity.

Recent Research

A further study from the University of Salzburg in 2014 *(3) investigated the efficacy of 4 different training protocols in well-trained athletes.

  • High Volume Training (HVT). All training is done at low intensity but with high work volumes. Easy long runs.
  • Threshold/Medium Intensity Training (THR). Training is carried out in the middle zone between easy running and hard intense running. Neither one nor the other.
  • High Intensity Interval Training (HIIT). Training is only high intensity efforts such as Interval Training, Hill Repeats, Threshold Runs.
  • Polarised Training (POL), which was an 80/20 mix of HVT and HIIT.

The Golden Rule of “80/20” – though the training protocol became known as Polarised Training.

The Results?

Very small improvements were observed in the HVT and THR groups while the HIIT group only improved Maximum Speed at Anaerobic Threshold levels. On the other hand the POL group improved performance variable in Vo2 peak, Time to Exhaustion and in Maximum Speed thereby demonstrating the efficacy of the protocol.

So, there we have it, if you wish to optimise your training time and efforts the best way to do this is to adopt a polarised approach.

How to Apply this to Everyday Training

Finding the right balance between Volume and Intensity
Finding the right balance between Volume and Intensity

The Importance of Low-to-High Intensity Proportions

According to polarised training protocols, approximately 80% of your training should be done at low intensity aerobic efforts and the remaining 20% at high or very high intensity. There is little advantage in medium or medium high intensity training sessions.

The researcher Stephen Seiler summarised his work with the following phrases:

“Low intensity (typically below 2 mmol/L blood lactate), longer duration training is effective in stimulating physiological adaptations and should not be viewed as wasted training time.”

Take home message – There is no such thing as junk miles and long easy runs are an essential part of training.

“HIIT should be a part of the training program of all exercisers and endurance athletes. However, about two training sessions per week using this modality seems to be sufficient for achieving performance gains without inducing excessive stress.”

Take home message – In order to improve we should be pushing our bodies hard during intense training sessions, but there is no need to do more than one to two hard sessions per week.

“There is reasonable evidence that an ~80:20 ratio of low to high intensity training (HIT) gives excellent long-term results among endurance athletes training daily.”

Take home message – 80% of your total training time should be spent in the easy, conversation speed modality and only 20% of your training time should be carried out at levels of intensity.

If you wish to read more about the 80/20 Rule I can highly recommend “80/20 Running” by Matt Fitzgerald.


*1 “The Use of Heart Rates to Monitor Exercise Intensity in Relation to Metabolic Variables.” Gilman MB, Welles CL. Int. J. Sports Med. 1993

*2 “Quantifying training intensity distribution in elite endurance athletes: is there evidence for an ‘‘optimal’’ distribution?”Seiler KS, Kjerland GO.

*3”Polarized training has greater impact on key endurance variables than threshold, high intensity or high volume trainin. Stöggl T and Sperlich B. Frontiers in Physiology, 2014.

Martin John Trout
Martin Trout is an all round Adventurer, an accomplished ultra runner, mountaineer, ski mountaineering instructor and trail running coach at Endurance Training in Progress. He’s been living in Italy since the 1990’s.