with  Martin J. Trout

In this article we aim to simplify several definitions that we may come across during our trail running days.

As trail runners, some of us may feel distanced to the thought of strict training programmes full of technical words, minutes, brackets and hyphens, which often seem more geared towards marathon and road runners.

However we may still really want to aim to improve our running form, get faster on the trails, or even spend more time running, and less walking – up those climbs!

In any case – in order to train properly for trail running, remember that it’s essential to carry out all prescribed workouts at the correct level of intensity, you may want to read our guide to the “Rate of Perceived Exertion”.

Here, coach Martin Trout explains some common terms that we can come across in our training.

  • Vo2max
  • Lactate Threshold
  • Neuromuscular Efficiency



This mystic looking abbreviation stands for the maximum amount of oxygen that your organism can effectively utilize. By this we mean the amount of oxygen that can be inhaled and then transferred to working muscles.

Numerous factors come into play such as:

  • Lung capacity
  • The quantity and volume of red blood cells which transport the oxygen to the muscles
  • The efficiency by which the oxygen is utilized by the mitochondria (the “powerhouses of the cell”), in the muscles

And Remember: Fast or hard running will

  • Stimulate lung capacity
  • Promote the growth of red blood cells and their oxygen carrying capability

Lactate Threshold

At lower work rates the body produces energy through Aerobic pathways utilizing a mix of:

  • Lipids (fat)
  • Glycogen
  • Oxygen

On the other hand as the amount of work increases we progressively utilize Anaerobic pathways – mainly glycogen without utilizing oxygen – to produce the required energy.

This production of energy through Anaerobic pathways enables us to go faster but it also has the side effect of increasing a substance known as lactate.

At low speeds lactate is absorbed and reutilized as fuel in the production of energy, however as the amount of lactate increases it is increasingly difficult for the body to absorb the lactate that has been produced.

Once the accumulation of lactate reaches a certain level (usually regarded as 4 millimol of lactate per liter of blood – 4mmol/L) the organism is no longer able to absorb all of the lactate being produced and therefore the quantity present in the blood increases.

At that point the athlete is living on borrowed time and will eventually have to slow down and/or stop!

Neuromuscular Efficiency

This is usually defined as the ability of the nervous system to properly recruit the correct muscles in the production and reduction of force, as well as dynamically stabilizing the body’s structure in all three planes of motion.

We can further refine this by saying that as the connection between the brain and the muscle improves the muscle will be able to produce more force and stability.

These improvements occur for two reasons.

  • Firstly the central nervous system learns to recruit more muscle fibres in response to greater challenge to the muscle (speed, force, weight).
  • Secondly the central nervous system also learns to send faster signals to the muscle fibres so they contract more quickly and with more force.

In training, sessions which involve speed work and up and downhill running all contribute to improving neuromuscular efficiency.

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.