Cycling / Triathlon Training in the Summer and Heat Stress
You might think that as summer is here and the mercury is rising, you’ll be performing at your best whether you’re running cycling swimming, or at putting all three together in a triathlon
However, there is plenty of information to support the fact that a higher temperature doesn’t necessarily result in higher podium positions. One the reasons behind this being that heat, it will affect our biological efficiency. There have been studies done, showing a change in performance during controlled exercise at 11°C compared to the same exertion performed at 21°C! So perhaps a summer race is not all it is cracked up to be!
Problem is that when exercising 70% of the energy we release is turned into heat. As the temperature rises, the body can’t regulate it’s system as well, causing a worsening cycle.
Heck even physics gives an athlete a kicking, as you are less buoyant in warm water!
Fluid in Fluid Out
When I do physical exertion to any significant degree indoors, I sweat. Actually, that’s not fair – I sweat like I’m a leaking hosepipe! A lovely picture I know, but it does mean that I have to be aware of replacing my electrolytes after rides/workouts. I have seen people collapse after doing an hour race on rowing machines during my uni days as a result of drinking insufficiently.
Frequently I will do an hour on Zwift, and even though I’ve drunk a couple of bottles, normally 2x 750ml bottle, and a 500ml of water in a recovery drink I still feel the effects after.
Talking the Garry Palmer of SportsTest he highlighted that a big issue for athletes is not merely the sweat bods like me. Amazingly producing ~2.2 litres of sweat per hour is about normal!! But that is only half of the story, because of insensible losses, things like moisture lost through breathing you cant just gulp that 2.2 litres back and be done with it.
To keep fit, you need to increase fluid intake by about 1.1 – 1.5x the amount of fluid lost to get those levels back to normal.SportsTest top tip:
Which explains why even when I’ve done everything I thought was right, and even weighed myself before and after a summers run, I’d still not replaced things correctly replacing weight for weight
What About Electrolytes?
This is where what you are doing matters the most. On an hour or two’s ride, the biggest concern is going to be replacing fluid. Simply making sure that your system has enough juice to keep the blood flowing
The main barrier here is simply how much can you absorb. On the
Thankfully there is some help out there if you want to be analytical. Certain companies Nuun, advocate use sweat tests in terms of body weight to determine how much you sweat you make, and what you should be taking to replenish things. Precision Hydration
But how does this relate to training in the heat? If you are doing long distance events, and you are sweating out your 2litres + an hour, you do need to replace these lost electrolytes whilst on the track. You cannot afford to make fueling missteps if you want to win. Screwing but big time however might have more of an impact than just affecting your time.
Losing excess sodium is a major problem in the heat. Yes,
Fatigue – we’ve all been in the situation of training heavily over several days, and just not had the get-up and go, but pair this is muscle weakness, and it might indicate you need to up your intake of salts off the bike.
Personally, I’ve found a power meter very effective for this, there has been at least one occasion in recent memory where I’d over trained, under replaced, and I simply couldn’t get the watts up (yes make your own jokes with it). Now
Athletes need to train in the heat not only to become “used to it”, but also to determine what the effect on their performance is. As fluid goes out, the cardiac output reduces – literally how much blood your heart pumps with each beat. Couple this with the fact as we know from earlier an athlete is going to have a harder time performing in the heat, we’ve got to expect a performance dip. An athlete can’t maintain their normal exercise level in these conditions so that have to slow down. Pushing harder will increase the heat burden further meaning that any additional speed is harder won than normal. Hence you can see why respecting the heat, and knowing your performance levels in the heat is so important
A lot of people will train for their triathlon in various parts. Today is a pool day, tomorrow bike day etc. Which is obviously going to mean different outfits. But the clothes you were can have as bigger impact in training than just on the race day
Athletes with clothing, indoors, or whole-body covering, tend to have a higher concentration of sweat – makes sense so far. The body obviously adapts to locations. But that adaptation will also extend to how and where the skin sweats.
We’ve two triathlon kits here. The chap the left has more exposed skin than the chap on the right (if he zipped his top up)
The sweat response develope on the skin, which is exposed. So in both kits, if the majority of training had been done in the race day clothing, that chap on the LEFT would have a greater ability to sweat and thus withstand the heat.
This does however then theoretically increase the risk of getting cramps due to electrolyte loss. Can you see how it is all connected, and for good performance in the heat you need to have prepared and trained?
But not all training is about pounding the pavement or mashing the pedals. Training is also about getting your body to absorb during the race, particularly in long-distance events. As mentioned there is a significant difference in how much you can absorb in different parts of a race. 1.5-2 litres per hour of gastric emptying when bouncing around on the bike, this will reduce further to 1-1.4 litres on the run. This can be maximised for a TRAINED individual.
One of the most effective ways to cope with the
What is Heat Stress
Heat stress is simply a exposure to temperatures which causes negative effects on the body. The most serious of which is heat stroke where the body has been unable to control it’s core temperature
Heat stroke tends to occur when there is a rapid change in body temperatures and the bodies temperature regulation mechanisms – sweating for example – fail. THIS IS SERIOUS. The symptoms are broad
- Confusion, altered mental status, slurred speech
- Loss of consciousness (coma)
- Hot, dry skin or profuse sweating
- Very high body temperature – 41ºC
If not treated the results are fatal
This seems almost a little excessive to be talking about here. But let’s briefly review our temperature regulation out on the circuit. In the water, we are wearing a tri suit, but if the water temp is > 25ºC, then wet suits are banned normally. So the water should be acting to help draw heat away from the body
Out on the bike, we have the wind acting in two mode, both to help sweat evaporate and help cool the body
It is then in the run where the risks are highest. Clothing is saturated with sweat, the athlete is going to be lower in electrolytes compared to the start, and running has the greater heat generation profile of the three sports.
Again training is going to be key in
Thinking that I’ll just take water in the ride, as I can pour it over myself, is almost as bad as not taking it at all. We need electrolytes in your race bottle, not just the wet stuff
Normally if you are not replacing your salts, but drinking plenty, your body will detect this and act accordingly. Your kidneys will keep hold of the electrolytes your body needs and dump any excess water into the urine. Your body controls this though checking bloods osmolality. But if you are doing training or racing in the heat, producing lots of sweat and drinking too much water, this can also cause problems.
Excess water or water not balanced by salts means you run a high risk of developing something call SIADH. Syndrome of Inappropriate Anti Duretic Hormone release. Essentially your body, because it is overwork, makes a mistake and absorbs more water than it should. Pushing your electrolytes further than the sweat and heat has already done. This can then lead to
Hyponatraemia – additional features
We discussed briefly that the low sodium can cause the feeling of fatigue. But if you enter SIADH, then things get a little nastier. Check this for a symptom list
- Lethargy – from a medical perspective, if I see a sportsperson in the clinic who is “tired all the time” one of the first things I’ll be looking for in the blood is their sodium levels.
- Seizure – this is the sort of thing which kills marathon runners/iron man contenders
All of these are going to put a major cramp in your race day.
The main point here about surviving in the heat has to be about drinking, drinking the right thing and training. Whilst not forgetting that the risks of heat do not disappear when the race stops. Fluid losses must be replaced steadily over the next 24hrs post-race.
Hopefully that will help a few people dealing with the hot weather, and was a good refresher myself before the London Triathlon this weekend!
If you want to read a little more about the training offered by SportsTest, you may find the review I did of the facility interesting
- Effect of Heat and Heat Acclimatization on Cycling Time Trial Performance and Pacing
- Galloway SD, Maughan RJ. Effects of ambient temperature on the capacity to perform prolonged cycle exercise in man. Med Sci Sports Exerc
- Water Requirements During Exercise in the Heat