The benefits of heat training and how to do it safely
Heat training has long been a staple of competitive athletes looking to get an edge while competing in hotter races, with heat training camps becoming popular for elites due to the relatively quick adaptations and performance gains they can yield.
Fundamentally, racing in hot weather will cause a dip in any athlete’s peak performance, but how adapted an athlete is to the heat through training protocols and their environment will determine how significant that dip is.
But if you’re not running your A-marathon in climes that would make a warm bath seem refreshing, and you’ve not snagged a place at Badwater or Western States for your once-in-a-lifetime trail ultra, is it really necessary?
Should you be heat training?
Do I really need to heat train for my summer half marathon in the UK?
Given that in London it’s already hit 32C in June this year (2022), putting in some heat training could be the difference between a great day and a complete disaster.
If you’ve had a long run that got ugly because you overheated, and if that’s left you thinking to yourself, “I hope it’s not that hot on race day,” you know some heat training is a good investment of your time.
How heat training helps improve fitness
Even if it isn’t hot on the big day, the adaptations from that preparation will improve your performance. Whether it’s 32C or 22C, heat training will improve your performance in temperate conditions, so it’s never a wasted effort.
One of the main adaptations heat training elicits is an increase in plasma volume. Plasma is the water content of blood and having more of it will allow you to sweat more easily.
As plasma volume rises, haemoglobin volume rises as well, this means more red blood cells are getting transported around the body, so more oxygen is being transported to the working muscles. That’s why people training in hotter countries can come over to the UK and perform at an incredibly high level.
Whether at home or abroad
Do I need to travel abroad to successfully implement heat training?
Thankfully, you don’t need to be a pro, nor have an unlimited bank balance and a lot of free time to burn to successfully incorporate heat training into your race preparation.
In this article, I’ll run through some key heat training protocols any runner can introduce to their training that won’t require a passport and two weeks off work.
Heat training strategies
Train in warmer conditions for a block
A two week block of active thermal loading, two weeks out from your race, where you spend 45 to 60 minutes a day making all your training sessions warmer can give some significant heat adaptations. The effect could be achieved either by just layering up for a run on a warm day, or even running on a treadmill and not turning on the fan. (It’s worth looking at the layout of your gym and picking the one with the least amount of ventilation for the purposes of heat training.)
The metric to look at here would be heart rate. If you see that for your daily 45-minute base run, with extra layering, your HR is up by 10 beats-per-minute (bpm) for the same effort, you can deduce this increase is due to the additional thermal stress.
These heated base runs will force your body to start diverting more blood flow to cooling down.
Don't overcook it
The reason you would only do this for a two week block and not a four week block, is because the heat training is a stressor, much like progression runs or intervals. You could become very heat acclimatised but stunt the progression of your fitness. It’s really a balancing act to get the optimum return from both types of training.
Ideally, after the two week block, you would do an extra warmer run every three days in the two weeks up to the race to top up the initial block and optimise your plasma volume.
A long term approach to heat training is best
For the best results, you would do a two week block of active thermal loading very early in the season, then throw in shorter one week blocks throughout between intensity-based training blocks.
This is due to thermal plasticity - once you’ve done that initial heating block, you’ll be able to top it up and progress on a much shorter block, giving you more time to focus on building your fitness nearer to the race.
Passive thermal loading
Two weeks out from your race, you could put in a week-long block of passive thermal loading. You’d use a sauna or a hot bath to start elevating your core temperature, starting at 15-20 minutes in the beginning of the block, but building up to 30 minutes.
In both instances, the shower or the sauna, you should be uncomfortably hot. You’re trying to introduce your body to an extreme situation to trigger the necessary adaptations. This means not drinking water, as it will negate the effects of the stressors you’re applying. (Seriously, don’t drink water in the sauna if you’re doing it for heat training, you’re just being uncomfortable for fun.)
For guidance in terms of your bath’s temperature, if you can read a book without sweating on it, it’s not hot enough. This is not a spa. It’s a means to better physical performance when it matters most.
Much like with active thermal loading, you would look to introduce another 30-minute sauna session or uncomfortably hot bath every three days before race day to maintain the optimum plasma volume.
Long distance running can take up a lot of free time, but there are efficient ways for people with jobs and families and busy lives to successfully incorporate heat training blocks into their regimes.
One way would be to do a passive thermal loading block where the loading was kickstarted by regular base-mileage.
For example, a daily session could start with a 20-30-minute run which would quick start the rise in core temperature, then jump into a hot bath, but only go for 15-20 minutes instead of the full 30 minutes. (Ideally an understanding partner would run this bath when you started your run, as you don’t want your core temperature to drop while you wait for your bath to be ready.) This could be slightly easier to do at the gym, running on the treadmill and then straight into the sauna.
If you operate on a four week training block with every fourth week being a down week, the down week is a great opportunity to introduce a passive or active thermal loading block.
Travel to your race destination to train
(If feasible) the gold standard is heading to a race-specific environment four to five weeks before your race, possibly even the location of the race itself, and training there, potentially timing that trip to double up with a family holiday. Obviously this kind of warm weather training specifically applies if you’re preparing to race abroad.
If you were able to implement the passive and active home methods with a trip to an environment that closely mimics the kind of heat you’re likely to be racing in, this will be fantastic preparation to succeed when it counts the most.
So heat training… is it really necessary?
- Too much heat will negatively impact your performance, but how much it will impact your performance is within your control.
- You don’t need to have the support network of a professional athlete to incorporate heat training into your running.
- It will benefit your running performance, even if race day temperatures are tamer than expected.
It might not be strictly necessary, but there is a strong argument that introducing some heat training protocols into your training offer more than just a marginal gain.