Breathing at High Altitude

Tour de France 2025 is a gruelling event. The 21-stage race begins on the flat. But this isn’t for long. The race winds its way through flat, hilly and finally mountainous terrain. This year is one of the most demanding Tour de France races. It includes 7 mountain stages with 5 mountain-top finishes. The highest point of the Tour will be climbing the eastern flank of the Col de la Loze, at 2,304 metres. In fact, the 2025 Tour de France route boasts a total elevation gain of 52,500 metres. It’s this high elevation that adds another challenge for the riders, that of breathing at high altitude. 

This blog explores the impact of altitude on breathing and performance during the Tour de France, and here are the key takeaways at a glance.

Key Takeaways

  • High altitude presents more of a challenge to breathing, resulting in reduced oxygen delivery to the legs and, therefore, early onset of fatigue.
  • Cycling at high altitudes can increase the build-up of lactic acid in the legs, reducing a rider’s performance.
  • POWERbreathe Inspiratory Muscle Training (IMT) improves the strength and stamina of the breathing muscles, helping riders to adapt to altitude as they climb.
  • Regular IMT with POWERbreathe reduces breathing fatigue, improves inspiratory capacity (as measured by the S-Index) and reduces the sensation of breathlessness.
  • A POWERbreathe IMT recovery session speeds up lactate clearance and improves recovery.

Breathing at High Altitude

As a cyclist climbs to a high altitude, breathing increases. This happens automatically. The reason for this is that the body is responding to less oxygen in each breath. As a result, ventilation increases as the cyclist tries to increase oxygen uptake. However, in spite of an increase in breathing, less oxygen will reach the working muscles, such as the legs. This is because signals are sent to the nervous system telling it to redirect oxygen from the legs to the diaphragm to keep up with breathing at altitude. Consequently, the cyclist’s leg muscles begin to suffer from fatigue. Inevitably, this affects performance.

Effects of High-Altitude Breathing

Breathing harder and quicker is an automatic response to the fall in air pressure. In addition to this, the heart works harder, too. It does this to try to increase the flow of oxygen-carrying red blood cells to the lungs. It’s a desperate bid to ensure the lungs don’t ‘steal’ the oxygen-carrying red blood cells from straining muscles.

Demonstration of the Metaboreflex

Another consequence of the challenges that breathing at high altitude inflicts on the body is the production of greater quantities of lactic acid. Cycling at altitude requires intense power and energy to climb the hills. But the body’s response to trying to produce energy with less oxygen is to produce larger amounts of lactic acid. It’s the build-up of lactic acid in the muscles that causes that feeling of ‘muscle burn’. It’s also responsible for slowing a cyclist down as it reduces the muscle’s ability to function and causes acute muscle fatigue. 

Thankfully, though, an inspiratory muscle recovery session using POWERbreathe IMT can help cyclists to recover faster, as it has been shown to speed up lactate clearance more effectively than traditional active recovery strategies. 

Preparing for the Challenges of Breathing at Altitude

This Review Article in Frontiers in Physiology investigates the use of respiratory muscle training (RMT), including inspiratory muscle training (IMT) with POWERbreathe, for acclimatising to the altitude. The review provides evidence that such training,

“…has the potential to minimize at least some of the limiting factors related to the respiratory system occurring during training / competition at altitude / in hypoxia.”

It goes on to suggest the expected benefits may include:

  1. A delay in the onset of premature fatigue.
  2. A delay in respiratory muscle metaboreflex onset/activation.
  3. An improvement in clearance and tolerance to anaerobic metabolite products.
  4. A decrease in the perception of dyspnea (‘air hunger’).
  5. An increase in oxygen saturation values.
  6. A more favourable blood redistribution to the locomotor muscles.

Respiratory Muscle Training for High-Altitude Performance

Recent findings shed light on how structured respiratory muscle training can support breathing at high altitude. This 48-week longitudinal study in elite endurance cyclists explored the effects of inspiratory muscle training using the POWERbreathe K4, alongside specific ventilatory strategies. 

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Training began with 2 sets of 30 inspirations daily, six days a week. From month three, the volume was adjusted to one set per day, with resistance gradually increased. This helped develop both inspiratory strength and fatigue resistance by targeting the diaphragm and intercostal muscles. The greatest performance improvements appeared during the final three months, when inspiratory loads became more individualised.

The study found a reduction in respiratory muscle metaboreflex and perceived exertion and a performance improvement, which are all beneficial when training or competing at altitude. The improvement in inspiratory capacity was identified by the increase in S-Index (Strength Index), which is a feature on the POWERbreathe K4 that measures inspiratory muscle strength. The rating compares a user’s inspiratory muscle strength with that of an average individual, based on research.  

Recovering from High-Altitude Breathing Problems

By incorporating breathing exercises for high altitude before the Tour de France or Giro d’Italia, cyclists will cope better with the challenges of breathing at high altitude. Inspiratory Muscle Training, such as with POWERbreathe, increases the strength and stamina of the breathing muscles, reducing breathing fatigue. Even better would be to perform IMT during turbo training. This will target the inspiratory muscles in the hunched position the athlete will be in during cycling.

Recovering from High Levels of Lactic Acid

For cyclists in the Tour de France and Giro d’Italia an IMT recovery session is proven to be beneficial as it:

Research shows that breathing against a small inspiratory load immediately after exercise reduces lactate by 16%. It also reduces lactate as soon as exercise finishes, unlike traditional active recovery, which may take 5 minutes to clear lactate.

Another bonus for Tour de France and Giro d’Italia riders is that subsequent research demonstrates that a post-exercise inspiratory resistive loading (after a Wingate test) reduces post-exercise effort perception and improves peak power on subsequent all-out maximal-intensity exercise. This is beneficial when riders need to perform at their best, day after day.

If you would like to know more about IMT for endurance cycling, then why not view this presentation by Dr. John Dickinson and Dr. Peter Brown of Inside Sport Science, University of Kent’s School of Sport and Exercise Sciences outreach programme.