With blustering winds and blistering temperatures, it can often be the weather conditions that see the undoing of many an athlete looking to put in a strong Ironman performance in Kona.
With just days to go until the 2023 women’s Ironman World Championship on the Big Island, we take a look at how heat impacts triathlon performance and share some top tips to help you race strong in the Kona heat.
How does heat impact performance?
We’ve all been there: heading out for a training session on an unexpectedly warm day and feeling like every step or turn of the pedals takes double the usual effort. Your heart is pounding. Your face turns bright red and that pace you’d usually be hitting with ease is nowhere to be found.
When we exercise in hot conditions, the body faces an increased strain on its physiological systems which has an impact on athletic performance. A study on the impact of weather conditions on marathon running performance analysed the results of all finishers’ performances in the major European and American marathons.
This study showed that increased temperatures correlated with decreased running speeds and a higher prevalence of race withdrawals. Laura Philipp touched on the impact of the Hawaii heat in one of her recent YouTube videos (below) from Maui, describing it as “brutal” after a tempo run session reminded her “how tough it is to perform under these conditions.”
Why does training and racing in the heat feel harder?
While training or racing in hot conditions, your core and skin temperature become elevated more rapidly. That means your body has to work much harder to keep you cool – diverting blood away from the muscles and organs to the skin surface for cooling. This results in a higher strain on the cardiovascular system, reduced capacity for aerobic performance and higher glycogen (energy) demands. Your sweat rate will also increase significantly in hot conditions, meaning the risk of dehydration – and the dreaded muscle cramps – are higher. In humid climates like Kona, that sweat evaporates far slower. So instead of the desired cooling effect – you’re just left feeling hot and sticky.
The result is a higher heart rate at lower intensities and an increased rate of perceived exertion. Heat stress doesn’t just make the effort of exercising feel harder. Analysis from the marathon running study even suggested that central fatigue kicks in before the body actually experiences an elevation in core body temperature. This can prompt some athletes to subconsciously slow down or reduce exercise intensity before internal temperatures reach a harmful level.
Top tips to race well in the IRONMAN Kona heat
Clearly then, heat can have a pretty big impact on a triathlete’s ability to perform. Not ideal, when your biggest race of the year is set to take place in the oven-like conditions of Kona. Studies into heat acclimation have shown that 7-14 days of heat exposure combined with aerobic exercise can have a significant benefit for your body’s ability to cope – and perform – in the heat. But with less than 2 weeks until the Ironman world championships, and with many age-groupers not able to arrive on the Big Island until a week (or less) before race day. Time, and taper, aren’t on our side. So what steps can you take to keep your cool and make it to the Ironman Kona finish line feeling strong?
We caught up with top-level age grouper and triathlon coach, Sophie Kirk, to get some practical pre-race and race day strategies to help you race well and optimise your performance in the Kona heat.
During race week
Don’t be tempted to train in the hottest part of the day to try and force heat adaptation
Once you arrive on the Big Island, it might be tempting to head out during the hottest part of the day to get your body used to what it’s going to experience on race day. But this can be a mistake, says Sophie. “If you’re arriving in Kona a week before the race, which a lot of age groupers do, then you’re probably not going to have that many hard/long workouts left anyway. You’re better off focusing on getting yourself into the right time zone for the race, which will mean getting out early.
Deliberately training during the hottest part of the day is going to do you more harm than good. All you’ll do is put additional stress on your body in taper week, when you should be resting up. It’s also hot enough early in the morning to get an idea of what you’re going to experience on race day.
The pre-race admin will mean you end up and about, on your feet in the middle of the day anyway so it’s not a great idea to load additional heat stress and unnecessary fatigue on top of that.”
Pre-load your hydration
It’s important not to leave thinking about your hydration levels until race day. The Kona heat will mean you’re losing significantly more salts and fluid through sweat even at rest, so it’s important to stay on top of hydration throughout race week. Sophie recommends drinking electrolytes throughout race week: “Arriving on the Island, particularly if you’ve come from a much cooler climate, is a big adjustment so I would concentrate on keeping hydrated. Make sure to drink electrolytes throughout the week, not just the day before or on race day. If you tend to get cramp, you’ll want to really dial in those salt levels and pre-load with electrolytes in the 2 days before the race.”
On race day
Manage your effort
At the Ironman World Championships, you’re going to want to put in your best performance. But it’s important to remember that going too hard and not factoring in the Kona heat could result in you blowing up – or worse. “For a lot of people going to Kona, it’s more about finishing and experiencing the event,” Sophie says. “Especially if it’s your first Kona world championships – you don’t want to go all that way and then not finish.”
“Don’t go out too hard at the start, particularly on the bike. There’s a lot going on, so it can be easy to go too hard and to forget to drink and get nutrition on board.
When it comes to the run, expect to slow down your pace compared to racing in cooler weather. In my experience, I’ve had to adjust my running speed by about 15 seconds per kilometre to ensure I reach the finish line safely without any issues like collapsing or other problems.
If you have heart rate data available and you know what heart rate you’ve been able to sustain for the bike and the run at previous Ironman races, then it’s also a good idea to keep an eye on your heart rate. Make sure you’re not going significantly over the heart rate you’ve held in the past. That might mean you have to go slower.”
Stay on top of your hydration
“You don’t want to get off the bike feeling dehydrated, because then it’s already too late.” Most Ironman athletes already prioritise hydration, but in Kona it’s really important to double down and take extra steps to prevent dehydration.
Typically, athletes will focus on hydrating before the race and topping up once they get on the bike. But for a race like Kona, Sophie recommends having a bottle to sip in T1 as well. That way you can start getting the fluids on board right away after the swim. Most athletes take the extra few seconds to reapply sunscreen in T1 anyway, so using that opportunity to start your hydration strategy will put you in a good place starting the bike.
“There’s a lot going on when you’re on the bike and it’s easy to forget to drink. I’ll usually make sure I’m drinking at least one 750ml bottle per hour. It’s important to make sure you’re taking on electrolytes, not just water. If you don’t want electrolytes in your bottles, you could take salt tablets instead.”
When it comes to the run, it’s worth knowing what the on-course nutrition is going to be. If it’s something you don’t like the taste of, or that you don’t tolerate too well, you might not want to rely on it. Sophie suggests taking your own small bottle with electrolytes in it, plus carrying some salt tablets to keep topped up.
“If you wait until you feel thirsty, then it’ll be too late. On the run I would grab a cup at every aid station, because most of the time you end up throwing half of it down yourself anyway. It can also be worth walking the aid stations to make sure you can get at least some fluids on board.”
Cooling is key
To avoid the potentially disastrous consequences of heat stress, doing everything you can to keep your body temperature down is key. Sophie suggests starting this cooling on the bike, picking up an extra water bottle at an aid station to throw over yourself to cool down. She also recommends opting for a cap, rather than a visor, for the run. Typically the aid stations will have ice and wet sponges available, so by choosing a cap you can put a sponge or ice in your cap to keep you cool. “You can also hold some ice in your hands or put it down your tri suit to stay cool.”
Slow down before heat stress ends your race
The Kona heat can be brutal. So, if you find yourself getting towards overheating – what can you do to avoid ending up in the medical tent? The first thing you’ll have to do is slow down, says Sophie. “You just have to start walking. And then it’s about getting the fluids in and cooling yourself down as much as possible. Dunk your head in water, grab the ice and just walk – or rest – until you start to feel better. It’s also important to note that when you’re overheating, it’s harder for you to eat and get fuel on board. So slow right down until you feel better and you can eat again.”
It comes back to the point Sophie made earlier. As much as you’ll want to put in your best effort at Kona, ultimately it’s all about getting to experience the race, making it to that finish line without compromising your health and being able to enjoy your time on the Island.
Heat-induced illness can have serious consequences, so make sure you know the signs of heat stress, look out for yourself and your fellow athletes out on the course and ask for help when you need it.
That’s the Kona heat covered, but what about those notorious crosswinds? Head over to our article on riding in a crosswind for all the tips you need.
