Heat training: What are benefits of using a heated-room for training?

Wondering how best to prepare for racing in hot humid conditions? With contrasting opinions out there on the benefits of heated-room training, coach Joe Beer and pro long-distance athlete Alice Hector weigh up the pros and cons

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Joe Beer says:

Hot and humid races, especially over mid to long-distance, present a huge environmental challenge. The athlete produces metabolic heat, probably in the range of 500-1,200 calories per hour, which requires sweating to rid heat from the body. If these heat management systems are poorly trained, the athlete is unable to absorb liquids properly and core temperature could go above a critical level.


Studies on heat training suggest that using specific hot environments in training sessions has a positive measurable effect on the ability to deal with environmental stress. This improved cellular thermotolerance can now even be seen by observing gene changes (e.g. transcription) to observe the internal processes of adapting to heat training.

I also think, though hard to measure, that an athlete who trains in hot conditions near to their goal race gets used to dealing with the mental pressure that running (less so riding) in the heat can bring. It sets them up for the adversity.

This adaption to better heat tolerance takes several sessions. Examples would be 5 x 90mins, achieving a rectal temperature of 38.5°C (suggested in Gibson et al 2015), or extended periods in hot conditions training every day in the heat. For 99% of age-groupers, obviously it’s not realistic to have either a rectal thermometer or a telemetric sensor on hand to monitor your training! A shed, conservatory or hot room can replicate hot conditions adequately, if the temperature is set above 30°C. You could also plan a training camp abroad in guaranteed warm weather at any one of many tri-specific resorts now open year-round.

Some athletes advocate sitting in saunas with occasional jogging on the spot – this isn’t super-scientific, but it’s mentally demanding to deal with high thermal stress, which can be increased progressively over time.

Alice Hector says:

Based off the back of anecdotal evidence from my experiences as a long-course triathlete, training in the heat definitely has its advantages.

For me, training in temperatures of between 32 and 40°C is horrible! But every time I have done so, I have raced off the back of it exceptionally well.

The theories match the outcome – if you train under extra duress, your body quickly learns to look after itself and acclimatise in more extreme conditions. When you return to training or racing in ‘normal’ temperatures, your body has such an easy job of managing core temperature, you’ll most likely bounce along merrily without a care in the world! I actually think training in the heat is as beneficial as altitude training with regards to fitness and conditioning.

There’s one unavoidable problem with heat training, though – it feels disgusting! I remember a run session I did in 40°C during a big heatwave in France. I was much slower than usual, and this got into my head leading into my next race. I went on to achieve my best-ever triathlon run split, which shows my negativity was pointless. So it’s important to disengage from your usual performance expectations when training in the heat, and not be put off by the inevitable slower pace.

Another issue is dehydration – hot conditions can obviously sap you dry very quickly. Fatigue sets in much earlier in the heat, and it’s really important to manage hydration and electrolyte balance. It’s a risky business if this goes awry.


If you’re training for a notoriously hot or humid race, you’ll definitely benefit from incorporating some heat training into your schedule. A couple of sessions a week for three weeks, of no more than 1hr, should bring about the necessary adaptations. I can’t say you’ll enjoy it all the time but used sensibly, heat training is a yes from me!

Found this useful? Then check out this 60min running workout for advanced athletes that’s ideal preparation for a hot race, and Ironman world champ Mirinda Carfrae’s top tips for coping with coping with the heat in long-distance triathlons