Summer might be over here in Australia, but with the mercury still regularly heading past 30 performance in the heat is a hot topic among many cyclists. In this post, we’ll use the recent example of the Tolland Handicap to discuss racing in the heat, and provide a few tips that can will hopefully stop you disappearing off the back of your next hot race or training ride.
The Tolland handicap is run by Tolland Cycling club over two days down in Wagga Wagga, NSW. For those unfamiliar with the handicap style of racing, it generally features laps of a longish circuit (~20 km in this case), with up to 10 groups on the road. The fastest ‘scratch’ group leaves long after the slowest groups, and handicapping of riders into groups is based on ability and previous results (or sometimes throwing darts at a board…). There is a prize for first across the line, as well as fastest time. The goal of the chief Handicapper is to have the groups all need to work together extremely well to have a chance of winning, and generally the race comes together pretty close to the finish.
The Saturday race was long, at ~100 km, and hot at around 40 degrees. This is into serious heat stress territory, and most riders struggled with the heat. Due to the consistent nature of the race with riders constantly pulling turns on the front, coupled with the lack of easier or descending parts of the course there was very little time to spend drinking water, unzipping jerseys, or pouring water over your head, all strategies that can help cool the body down in extreme heat.
Saturday: 1h54min, 307 NP, 177 average HR, 39 degrees
Sunday: 1h33min, 337 NP, 174 average HR, 29.9 degrees
You can see from the lower power output for a similar heart rate on Saturday vs Sunday (representing increased internal load) that heat can clearly limit performance. This is supported by a bunch of studies showing slower running times and reduced TT power output. The reasons for this are numerous and complex, but what matters is how we combat it.
So what can we do about it?
In basic terms, heat is built up in the body through metabolic heat production (a by product of your muscles working) and environmental factors. Far more energy is lost to heat than actually goes into turning the pedals around during exercise, and when it’s hot it can be hard to get rid of the built up heat.
There are four major ways the body exchanges heat with the environment. Simply put, these are radiation (think putting your hand near a hot fire), conduction (touching a block of ice), convection (air moving past the skin) and evaporation (sweating and respiratory heat losses). We can use all of these in cycling to help cool us down when the weather heats up.
If you have a major event coming up where you know it’ll be hot, spending some time adapting to higher temperatures is key. Proper heat adaptation can result in reduced core temperature, increased plasma volume, improved sweat response, and reduced perceptual sensitivity to heat.
Generally, 7 days of exposure will be enough to get most of the benefit, but more full adaptation in terms of performance outcomes usually takes 10-14 days. There is no universally recommended protocol, but the general advice is to exercise in hotter conditions at an intensity and in an environment which gets the sweat rate and body temperature up, and to maintain it for 60-90 minutes for 4-8 sessions. For those living or training in colder environments, you can wear more clothing or turn the fan down to elicit similar results. It appears that there is limited benefit to passive heat exposure (chilling out in the sauna with Netflix won’t work, sorry). Higher initial fitness level also appears to help with heat acclimatisation.
Ever seen the pros warming up wearing ice vests in France in July? The scientific basis for this is pretty sound, with pre-cooling strategies being shown to help reduce the core temperature before the event, and to delay the increase in core temp for short-medium distance races. Ice vests and ice hoods are best - avoid pre-cooling the legs. Pre-cooling also reduces the perceived heat stress. Events where it doesn’t seem to work are maximal sprints (track racing mostly, you’ll have warmed up by the end of a crit or road race) and very long events like Ironman or long sportives.
Sadly for our lads, there weren’t any ice vests kicking around at the Ladysmith Memorial Hall.
Although an ice vest during the race might seem like a great idea on a hot January day, the extra weight might not help on the bergs. Enter grandma’s old stockings. Filled with ice and stuffed down the back of a jersey, these can help reduce RPE and discomfort due to the heat, and might help mental functioning. In general, cooling the head and neck has been shown to be great for this, so tipping a bottle of water over the head isn't a bad plan either.
However - none of these strategies have strongly been shown to actually decrease thermal strain during the race, so be careful about over using them as you may miss signs that you’re working too hard.
One other important thing you can do is reduce your expectations of your ability to sustain the same power output you’d expect in cooler temperatures. So don’t go out trying to hold a solo breakaway at your normal threshold pace!
After the event it’ll be important to cool down, and drink plenty of fluids. Some electrolyte drink may help to replace anything lost to sweat as well. Have a light active cool down ride at recovery pace, throw in another ice sock, or go for a swim to get that core body temperature down.
We hope this article helps you achieve your goals! If you have any further questions, don’t hesitate to get in touch at firstname.lastname@example.org or head over to nero.bike/coaching
The normal caveats apply - advice given in this blog is of a general nature, and your personal circumstances should be considered.