Heat Acclimation

Preparing for an event in the heat, such as the Marathon de Sables? Performance in the heat can be significantly impaired, through the impact of an increase in body temperature as well as an elevated risk of dehydration.

Bookings are now open for heat acclimation for Marathon des Sables 2023.

Conditions in Morocco for the Marathon des Sables are generally hot, and have been known to reach 50C.  So it is wise to do all you can to prepare. 

Every year for the past 10 years we have helped people prepare in our environmental chamber.  We set the conditions to ~40C and 30% humidity, to match likely conditions in the desert.  Regular sessions in the chamber causes several physiological adaptations that can reduce the adverse effects of heat on exercise performance.  

We also include an assessment of sweat sodium concentration, and help you to optimise your hydration strategy based on your sweat rate and sweat sodium concentration.

To make your booking, please follow this link to our office calandar.

The bookings schedule runs from 27th March – 19th April, with 5 x 2 hours slots available to book on most days. 

The time slots on offer are 2 hours.  This includes time before and after your session in the chamber (for pre/post weighing for calculating sweat rate, discussing the session, shower afterwards etc) – you will only be exercising for around 60 minutes.   

Each slot can be booked twice – ie 2 people per session. 

If you would like to book sessions before the 27th March, please contact us directly with the dates/times you are interested in.

If you are interested in further support in preparation for Marathon des Sables, such as a physiology test to inform training, please visit this page for more information about what is available.

heat chamber

What is involved?

Whilst a one-off session in the heat chamber would give you an idea of how you respond, a series of sessions would be much more useful as it will allow you to acclimate to the heat, as well as trialling kit, and potentially also different nutrition/hydration strategies. 

We aim for at least an hour of exercise in the chamber, with the target of getting your temperature up to around 38.5C for the greatest duration possible.  During the session we will take regular measurements of your heart rate, perception of effort, perception of heat stress and tympanic (ear) temperature.  We will also get measures of your body mass pre and post session, and how much you drank, in order to calculate your sweat rate.

We can also measure sweat sodium concentration.  This helps us track your adaptation, but can also be useful in guiding your hydration stategy, particularly if you are classed as a very salty sweater.

Exercise can take place on a treadmill or bike.


The number of heat acclimation sessions you may need to book with us to prepare for your event depends on many factors, such as whether you’ve been acclimated before, whether you’re male or female, and what heat acclimation resources you have access to outside the lab. 

Ideally, you should do your heat acclimation as close to your departure as possible so you will be ready for your event. However, we understand that your availability and daily schedule plays a part in when you can come in for your sessions, and it is also possible to complete an acclimation block a few weeks or even months before an event, and then 'top up' with a small number of sessions prior to departure.

Our ideal scenario for you to achieve maximal adaptations is to complete 6 sessions in the chamber and to supplement this with passive heat exposures. Our general advice is the more sessions you can complete the better. This may not be possible/necessary for everyone, so we are happy to discuss your individual situation and needs, and come up with an appropriate plan.

Who is it for?

Anyone who is preparing for an event in the heat can access our service. There is also evidence emerging that the physiological adaptations to exercising in the heat can provide benefits when exercising at altitude, as well as when exercising in temperate conditions.  Exercise mode and intensity is adapted to suit the individual’s requirements. 

What do you get?

After each session you will receive a report with your data.  This explains how you responded during the session,  tracks adaptations over time and advises on how much you need to drink to rehydrate post-session. 

After your final session, you will receive a more comprehensive report which will include an analysis of how you have adapted to the heat,  information on your sweat rate and how much you need to drink to maintain hydration, as well as your sweat sodium concentration and how this influences your hydration strategy.  

Throughout the course of sessions we will also be able to help you determine an optimal, appropriate pacing strategy for your event.  You will gain an understanding of how you feel in the heat and how this relates to your physiology, so that you can keep your hydration on track and adapt exercise intensity as necessary to help you avoid overheating.

Cost for the Marathon des Sable heat sessions

  • 1 – 3 sessions: £85 per session
  • 4 – 7 sessions: 10% discount, so £68 per session
  • 8+ sessions: 20% discount, so £68 per sessioNS

CANCELLATIONS OR CHANGES: within 24 hours of your session will incur a £50 charge.