Heartrate / Zones / Temperature

Hi there,

Maybe I didn’t look hard enough but I didn’t find up to now an answer regarding zones and temperature. Let me explain what I mean, but first I recap :

  • with training we seek adaptations
  • workouts are usually prescribed using zones
  • zones can be defined with Heartrate / Watts / RPE
  • the environment impacts our Heartrate and RPE, not the watts

Now for the seek of the discussion :

  1. if I train (indoor) with no fan (what a pity) and a quite elevated temperature, for the same watts, my heartrate and my RPE will be higher;
  2. if I train (indoor) with a super fan and a temperature about 11°C (lwhich seems optimal temperature according to S.Cheung), same watts but my heartrate would be lower and RPE lower.

In both cases, the watts are in the prescribed zone (let’s say zone 2 Endurance - Wahoo Systm) but in the first scenario the heartrate is in zone 3 Tempo and in the second scenario in zone 1 Recovery.

What would be the effect on the training response appart from the fact that I would be more tired after the second scenario ?

My question is perhaps too theoretical but would it be necessary to adapt the wattage to be in the good zone with regard to the heart rate and the RPE ?

Many thans for your help !

Regards from Switzerland



Hi flongchamp,
It can be hard to find the proper articles / research when you have a specific question like that.

  1. When using power zones the training response (adaption) for your muscles will be equal regardless the temperature. The cardiovascular response as well as the general fatigue will be different, exactly like you experience it.

  2. When using heart rate zones, the cardiovasculair response (adaption) will be equal, but your muscles will have a smaller stimulus (in the heat).

The performance of muscles under varying temperature conditions is not significantly different, assuming a proper warm-up.
The heart muscle has a harder time at higher temperatures because you need to sweat quite a bit more.

Make sure you stay hydrated in warmer environments and use clothing to keep you warm in colder environments (otherwise the blood flow will be insufficient).

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Thank you @kjeldbontenbal but I am not so convinced by the answer (sorry). Didi you watch The Impact of Cold on Metabolism and Fueling - Fast Talk Laboratories (fasttalklabs.com) ?
S. Cheung mentions that with temperature between 0°C and 22°C there is a 40% difference in the fat consumption in favor of 0°C.

With low temperature the body is more reliant on fat combustion, up to 10-20% higher V02max. Less need of CHO.

Next question… would be low temperature a good option for training low VLamax ?

I did not see that episode, thanks for the link.

Hi @flongchamp,

Thanks for the question and sorry I only have time for a very short answer. But you are right - different ambient temperature and airflow around your body is going to lead to different responses. Obviously, heart rate is going to go up both due to dehydration and a greater demand for blood flow to the skin to release heat. But, your body’s substrate usage will also be different (as you pointed out,) and the anaerobic/aerobic contribution can potentially be altered (depending on how extreme the difference is and how long you train in the conditions.)

However, what I consider most important is looking at the various stressors on your body and differentiating between which are adaptative and which are not. So the direct local adaptations due to the power you put out will likely be similar. But in the heat with no fan, you are adding other stressors that your body will also have to recover from. The question is whether they are just delaying recovery or adding additional adaptive signals.

There is some evidence that exercising in the heat can have similar effects to exercising in the heat, so there is an argument that the benefits are increased (at least slightly.) That said, I personally think they are minor and not worth the stress and non-adaptive damage you are doing to your body. Not to mention the potential dangers of training in a heated room with no air flow.

Dr Cheung is the one who introduced me to the research showing the similar effects to altitude training. But he’s a big proponent of keeping the room cold when you’re on the trainer. I haven’t asked him why, but I think he’d agree that you’re adding a lot of non-adaptive stress and damage.

Hope that helps!