The vertical kilometre, or KV for those in the know, is undoubtedly one of the most brutal aspects of trail running. Short distance, huge elevation gain, no room for approximation. On a vertical kilometre, there are no false flats to recover on or long descents to catch your breath: it's uphill from start to finish.

Often perceived as a challenge reserved for elites, the vertical kilometre is nevertheless a formidable tool for progressing in trail running, provided you understand its requirements and approach it intelligently. The Baouw team, experts in​ sports nutrition, will guide you through this article to ensure that your first KV is an unforgettable experience! 

What is a vertical kilometre?

A vertical kilometre is a race with a simple objective... on paper: to climb 1,000 metres of elevation gain over the shortest possible distance, usually less than 5 kilometres. The average gradient is often over 20%, with some sections significantly steeper. Suffice to say that mastery of walking poles is essential! 

Unlike a traditional trail run, KV does not seek diversity. It pushes the body to its limits with continuous, intense and relentless effort. Your time depends as much on your physical ability as it does on your effort management and mental strength.

In what way is the vertical kilometre a discipline in its own right?

KV is not a shortened trail run but a specific discipline with its own codes, sensations and pitfalls. The effort is short but extremely demanding. Very quickly, your heart rate races, your legs burn, and the temptation to start too fast comes at a high price. This format requires real clarity of mind: you have to accept discomfort, manage pain and keep going even when everything tells you to slow down. Mentally, it's a formidable exercise... but also incredibly rewarding! 

The role of energy pathways: why does KV cause your heart rate to skyrocket?

Over a vertical kilometre, energy systems are heavily taxed. While aerobic capacity still plays a key role, it is quickly supplemented by significant anaerobic contribution, especially on the steepest slopes or during changes in pace. It is precisely this interaction that makes the effort so difficult to maintain. Lactate builds up, breathing becomes jerky, and the slightest mistake in pacing (managing your effort and speed) can cause a real physiological wall. The stronger your aerobic base, the longer you can delay this critical tipping point. Fortunately, all of this can be worked on: we invite you to read our article ¨​prepare your first trail race”. 

A challenge accessible to all?

Contrary to what one might think, vertical kilometre running is not just for elite endurance athletes. It can be suitable for many different types of runners, provided they prepare properly. Both powerful runners and endurance trail runners can perform well thanks to excellent effort management.

But what about trail running beginners? In this case, the vertical kilometre can be a great indicator... or not. Without sufficient aerobic fitness or muscle strength, there is a real risk of overworking your body. It is therefore important to integrate it intelligently into your overall training programme and only attempt it when you are ready. 

How to train for a vertical kilometre?​

Preparing for a vertical kilometre race is not just about ultra-intensive training sessions. It requires a solid foundation built up over time. Of course, hill training is key, but it should never be disconnected from the rest of your training and should not account for 80% of it.

Bear in mind that a coherent plan rests on three pillars:

• a solid aerobic base, with plenty offundamental endurance,
• specific uphill sessions to develop power,
• targeted muscle strengthening to withstand stress.

Without this foundation, interval sessions and intense training can even become counterproductive. On a vertical kilometre, there is no room for improvisation!

Is there an ideal training frequency for improving in KV?

Before rushing headlong into it, remember that vertical kilometres are demanding and therefore costly for the body. Depending on your sporting habits, you can maintain your running pace or follow a well-defined training plan for trail running AND incorporate one or two specific sessions per week. Your goal will then be to improve your climbing speed by tackling steep slopes, working in intervals and stages. 

The rest of the time should be devoted to basic endurance training, active recovery and muscle strengthening. It is this carefully considered balance that will not only enable you to progress without injury, but also to transfer the benefits of KV training to other distances.

Running or walking: a little tip on climbing technique? 

In vertical kilometres, the line between running and walking is thin. Very thin! Keep in mind that active walking is often more effective than running on steep slopes, provided it is done correctly: good posture, a steady pace and looking ahead will have a positive impact on your performance. One of the most common mistakes is trying to run at all costs.

Nutrition and hydration on a vertical kilometre

As the effort is short, nutrition during the race is not essential. However, arriving with available​ energy reserves disponibles et une bonne hydratation permet d’exprimer pleinement ton potentiel sur le terrain.

And after your workout, you can focus fully on recovery. The muscular and nervous stress you will have been under should not be overlooked.

Here's what you should NOT do on the big day!

On the big day, galvanised by adrenaline, your goal and your desire to push yourself, don't make the classic mistake of starting too fast! In reality, the KV is often won in the last third, when your body is already well worn out.

The most common errors are simple, but nevertheless costly:

• starting above your actual abilities,
• neglect warming up and stretching after the race,
• underestimate recovery.

We won't hide the fact that you may feel your first vertical kilometre... but you will also feel immense satisfaction! 

KV and optimised trail performance

The KV is a first-rate tool for improving power, running economy and mental resilience: nothing less! It also strengthens your ability to cope with elevation gain and makes long climbs ‘easier’ in classic trail running. It is also an excellent training ground for learning how to manage intensity, sensations and pain, essential skills for any trail runner, from short distances to ultras. So, will you choose Fully or Chamonix for your next vertical kilometre challenge?