I’ve always appreciated my place in the athletic world where sweating is seen as a sign of exertion and the search for improvement. Many of my friends see sweat as a sign of poor hygiene or a feverish response to a virus, given their ‘workplace’ is contained between four walls and often in a sedentary desk job.
Sweat is our bodies attempt to offload heat to maintain core body temperature when external and/or internal stressors are threatening to elevate it. Therefore, sweat is our friend in sport, so long as we are vigilant and replace the lost fluids and electrolytes along the way.
One way to improve our sweat response is to encourage it through consistent exposure to heat and/or exercise. Sweat and the subsequent fluid loss triggers our body to increase blood plasma volume which in turn improves our body’s ability to sweat sooner and more effectively. The advantage being a better ability to regulate our core body temperature on race day.
I have been using various forms of heat acclimation for a number of years, usually in the lead up to a major event that is likely to occur in warmer climes. Living way down in New Zealand has often meant my preparation for major summer northern hemisphere events has happened during the cold, winter months at home. So, I've adopted a combination of both active and passive heat acclimation protocols that I have found work for me...
Active heat training
Firstly, the difference between active and passive heat exposure is essentially that active exposure is creating an uncomfortably hot environment during the training session itself, where passive exposure generally happens immediately following a training session. The reason I have used both is because I’ve found they each offer their own pros and cons.
Active heat exposure for me has generally involved cycling indoors without a fan, perhaps with extra clothing and/or a heater going. It has involved running outside or on a treadmill, again wearing enough clothing to make it feel uncomfortably hot. I have also been known to swim in the local indoor heated pool wearing my wetsuit, pretending not to be conscious of the weird looks from the lanes next to me and the concerned looking lifeguards.
The key consideration for active heat sessions is that the heat needs to offer the predominant stress. This means my sessions will usually be very aerobic in intensity (Zones 1 and 2 only) and will often mean heart rate is 10-20 beats per minute higher for a given pace, intensity or output than without the heat stress.
The good thing about active heat work is that it's very easily achievable at little to no extra cost (except the extra power bill coming from the laundry and/or heater), but it can compromise on your ability to hit higher levels of intensity (above Zone 2 or aerobic threshold), as well as leaving you a bit groggy afterwards if hydration levels have plummeted.
Passive heat training
Passive heat exposure is probably my favourite and involves either a hot bath (approximately 40°C / 100°F and deep enough to cover the entire body up to the neck) or a sauna immediately following a training session (while core body temperature is still temporarily elevated following the exercise). This can be for 15-20 minutes initially and build up towards 25-30 minutes by the end of 7-8 consecutive days.
Unless you have a sensor to track your core temperature, another option I have used is a heart rate monitor where I've aimed for roughly a heart rate in mid-to -high Zone 2 while sitting passively in the heat. This is also a way to track progress as each subsequent bath or sauna should show a slight lowering of HR for the same level of heat exposure. Always take it slowly exiting the bath or sauna too. I would always have a chair and a bottle of fluids close by to ‘sit and sip’ for a few minutes while my heart rate came back down and I was confident in my composure again.
I would usually finish the passive heat block about 7-10 days before the race and aim for another hot bath or sauna following training every second or third day thereafter for maintenance, until I reached the destination of the event and was exposed to the local climate accordingly.
The good thing with passive heat exposure is it allows you to hit your training targets without the compromise that comes with heat stress, however it does rely on you forking out some extra dough to cover the heat bill for all of those 40°C (100°F) degree baths, or having access to a sauna close enough to climb into quite soon after finishing your training.
Of course these approaches have been followed when I have been in a different part of the world (cooler climate) to the destination of my impending race. If you find yourself training in a similar climate to your goal event, you might get enough heat stress simply by training outdoors each day. However, even then I have seen benefits in passive heat training, given blood plasma volume expansion enhances cardiac output, which means you can pump more blood and deliver more oxygen to working muscles. This is going to be a big advantage regardless of what climate you're competing in!
The only warning I have from personal experience is to make sure you replace the extra lost fluids and electrolytes after each session during the heat training block. While you may feel OK immediately following the heat session, it can definitely have a ‘hangover’ effect and compromise training the next day if you don’t focus on replacing the lost fluids. Weighing yourself before training can be a good way to hold yourself accountable, with the goal being to keep drinking after the training and heat exposure until you're back to the same or higher weight than before you started.
So get out there and get your sweat on. It’s a wonderful thing to be involved in a world that celebrates those of us who sweat!
