How to Fuel For Success on HOT Days
Updated for 2020
Training and racing in cold weather are entirely different than training and racing in the heat. Strange things happen in hot conditions; some athletes thrive while others fall apart. Your nutrition program has a lot to do with how well you handle extreme conditions. Dehydration, cramping, and GI distress can wreak havoc on your performance, so it’s important to pay attention to your sweat rate.
In very arid environments (like in Arizona and Utah), sweat can evaporate almost immediately, which can make it difficult to figure out your sweat rate. In dry conditions-your sweat rate can be at it’s highest-even though you don’t see or feel any moisture on your skin. In hot conditions, hydration (the consumption of water and electrolytes) is always more important than your caloric intake. This is not to say calories are not important, but the consumption of calories without a proper hydration strategy will, ultimately, lead to disaster. It’s important to determine your hydration requirements before calculating how many calories you should consume.
Sweat is your body’s mechanism to cool itself in hot environments. The more trained you are, the better your mechanism to sweat and cool yourself becomes. If you have a high sweat rate, it’s a sign that your body has acclimated to the heat. To sustain a high sweat rate, which is ultimately what you want in hot conditions, you have to maintain the appropriate amount of fluid.
THE DANGERS OF DEHYDRATION
Dehydration significantly reduces your ability to absorb calories and nutrients. There’s a direct correlation between dehydration and your body’s ability to absorb nutrients.
Even a 1% drop in internal fluids requires your heart rate to increase in order to sustain an adequate sweat rate. Obviously, not what any endurance athlete wants to happen.
If you suffer a 2% drop in total internal fluids, you’ll experience a serious decrease in your performance. Best case scenario, you’ll be diminished to “the walk of shame.”
You could even suffer from heatstroke. Hydration is critical to performance, especially in hot conditions.
THE MOST COMMON MISTAKES
We’ve all experienced it, in some variation. It’s basically a “rite of passage” for any serious endurance athlete who’s ever pined on a number. Everything seems to be going well, and then it hits. If you’re lucky, you can get through it and struggle to the line. Those are fortunate days. But, more often than not, it’s the end of the road- and it’s not pretty.
We’re talking about cramping; biblical cramping.
There’s also the danger of gastrointestinal distress, which can be a life-changing event. We’re talking about nausea, vomiting, and explosive-diarrhea of the legendary caliber.
They’re the stories you tell your friends when they ask you: “what’s the worst thing that could happen?”
Most athletes prioritize caloric intake and consume water arbitrarily without considering concentration percentages or osmolality, which is exactly what you shouldn’t be doing.
The most important consideration, when racing in the heat, is hydration. If you don’t make sure your hydration requirements are being met before consuming additional calories cramping, dehydration, and GI distress can wreck your day.
You probably won’t experience cramping or dehydration issues when training or racing for an hour or less. For longer sessions, however, it’s essential to stay on top of your hydration and electrolyte consumption. At First Endurance we recommend a balance of all five electrolytes (sodium, potassium, calcium, magnesium, chloride) in order to ensure proper muscular contraction and cellular respiration. When electrolytes are in balance, performance improves and the risk of cramping is eliminated.
Remember: training and racing in the heat will most likely be derailed by dehydration way before it’s affected by a nutrition bonk.
Because nutrition absorption gets compromised significantly without the proper hydration, it’s paramount to focus first on hydration and then on calories. Every athlete responds differently in the heat. In extremely hot and long sessions, it’s not out of the question for some athletes to push 40-50 ounces of liquid per hour to sustain efforts, while others can get away with as little as 24-30 ounces.
TIP: In hot conditions we recommend drinking 12oz fluid for every 100 calories. If you know you will only consume 24oz of fluid per hour, then your maximum caloric intake during exercise should be 200. Attempting to force calories in without proper hydration is a recipe for gastric distress, cramping, and poor performance.
HOW TO FUEL FOR SUCCESS IN THE HEAT
It’s always best to test your hydration and fueling strategies in training in order to figure out what works best for you. As the duration of training and racing increases, it becomes more and more important to pay attention to your fluid and caloric intake so you can balance the two appropriately in order to ensure success. Only consume the maximum calories that match your hydration consumption.
Your pace also affects how many calories you need. A threshold pace will require significantly more calories than a slow pace, and thus, significantly more fluid.
You should change your hydration and fueling strategies during your training or racing as the temperature and/or pace change. If it starts out cold and heats up as the day progresses, be sure to adjust your caloric intake and hydration accordingly.
**Following every workout you should ask yourself:
1) Have I used up my glycogen? If so, have a serving of Ultragen.
2) How dehydrated am I/do I feel like I need electrolytes? If depleted, consuming a scoop of EFS or EFS-PRO mixed in 12-20oz water works great.
several times it’s mentioned the importance of determining ones hydration consumption
/needs/capacity but I don’t see anywhere how one can determine this?
Bill,
Great question. Its really quite easy but also can be too difficult to extrapolate into real-world settings. To determine hydration needs you can simply weigh yourself prior to a workout and also after a workout. Subtract out any fluids you consumed. The difference is your total fluid loss during that workout. The trouble is that this is only appropriate for that exact pace at that exact temperature doing that precise type of exercise. If the following day its 15 degrees cooler or your pace is different then you already changed your fluid needs significantly. Because of this its hard to give an exact formula or recommendation. What you can do is take the knowledge you gain from this article and try to apply it on a daily basis making some adjustments as variables change. Generally this means that if you don’t sweat a lot you don’t need a lot of electrolytes or fluids. IF you do sweat a lot you need a lot of electrolytes and fluids. Calories remain consistent regardless of the ambient temps.
Really interesting discussion on hydration limits and how idiosyncratic they are by athlete. Is it the same for caloric limits? I’ve read in a few places that the body can only metabolize ~240 calories per hour. If true, that would seem to put a limit on how much EFS-pro (plus liquid shot) one could put back per hour. So, I’m asking what’s the real limit- hydration (sounds like up to 60oz/hour, which would mean up to 500 calories per hour with EFS-pro) or calories? Thanks much.
PS- if you’re going to answer by saying it depends on the athlete, could you also offer some broad guidelines around which to experiment, please?
Doug,
Well put. And yes, it does depend on the athlete. These broad restrictions are based on clinical studies and what they have found. Data returned from all clinical studies typically fall within a bell curve where some athletes absorb considerably more and some less. The average becomes the recommendation with an end result of about 240 calories. Unfortunately these studies also leave many questions unanswered. One has to do with osmolality of the drink/calories being consumed versus just a straight concentration. As osmolality is reduced so is our ability to absorb at higher rates. How much precisely is difficult to know because we are not aware of a clinical study that has researched this specifically. So this leaves us with anecdotal evidence and many, many years of working with athletes and their nutrition program. We have worked with many athletes that can consume upwards of 500 calories per hour with no apparent digestive issues.
More often athletes push calories without paying attention to concentration/osmolality which is why we recommend to first consider total fluid ounces one is willing to consume and then calculate backwards how many calories this will deliver. We recommend 100 calories for each 12oz. In the end its only those calories that are fully and easily absorbed that really offer benefit. Calories that are not absorbed properly leave athletes with gastric distress, burping, diarrhea, bloating. So this can become your measure, however it truly takes longer 4+ hour workouts before gastric symptoms manifest. Start at 240 calories per hour properly mixed. On subsequent workouts keep increasing this by about 40-60 calories until you notice gastric distress during or for a couple hours following your workout. At that point you likely know your personal limit.
Also know that through years of experience, we have found athletes fueling for long distance racing typically try and consume far more calories than they truly need. Its not needed to push a lot of calories for events 8-24 hours. At these distances we spend most of our time at sub-threshold effort which is an effort that burns mostly fat. As opposed to shorter distance racing where athletes would burn more glycogen. Since we only need to replace glycogen calories, and since we are at this sub-threshold pace we burn less glycogen calories per hour than short races. Because of this, its really not necessary to push calories to these high limits. We have found a 150lb athlete to be well fueled and strong consuming 220-250 calories per hour for 12 hour races, when pacing is done properly.
Can’t thank you enough for your very thorough response. I’ll admit that I’d not paid attention to osmolality until I began using the 1st Endurance suite of nutrition products, which I love. I’m taking away from your response that basing a hydration-caloric intake strategy on hyrdration-driven osmolality is the most wise approach to hone in on what my body really needs.
On a related tangent, have you all done studies on athletes who don’t make their own cortisol and have to take it in orally via corticosteriods (see: Congenital Adrenal Hyperplasia)? thanks again-
Doug,
You are welcome. We do not have any experience or knowledge regarding congenial adrenal hyperplasia. It does seem to open up a whole slew of questions as it relates to substrate use and recovery.
This is a great article and follow up questions. It answered many of the questions I have, regarding long course fueling and training and racing in the heat. I’m trying to come up with a solid plan to use only FE and avoid course nutrition for IM races, for consistency . The concentrated EFS Pro is a great idea – getting water for dilution won’t be a problem. I’m really looking forward to experimenting with these ideas. Thank you!
Guilherme Campos triathlete send me this article. Great article! Finally FE is selling um Brazil.
Yes we are very excited to be selling in Brazil.
I am very glad sharing my experience using FE products on my training and racing got you motivated to give them a go down in Brazil Caique! Brazil has a huge and continuously grown endurance/Tri community that will benefit a lot from FE products now available inside the country!
Can I mix a concentrated bottle of EFS Pro (like a 3 hour bottle) & just sip some every 30 minutes along with the proper amount of water?
Yes you can do this.
Did a 3 hour ride today in very hot conditions in Texas following a one hour swim. Consumed 24 ounces of water every 30 minutes with 120 calories of EFS Pro as my hydration and calories. Felt good the whole ride did not feel depleted or dehydrated. That said, I still lost 6 lbs during the ride (180 base weight) despite taking in 48 ounces per hour. How much water can you drink in an hour. 48 ounces seems to be about my limit. When racing triathlon, any suggestions as to how you carry EFS pro for a half or full Ironman? My half Ironman rides are typically 2:30 – 2:50 so that would indicate 5 packets of EFS Pro. Carrying it an mixing it is not really a good option so it would need to be premixed and concentrated. Has anybody tried this? Any tips would be welcome
Joe,
Its possible some or much of the water weight you are losing is happening in the pool. 48 ounces per hour is a decent amount, though we have had athletes push 60oz per hour. Its really very athlete specific and learning what your hydration limit is will go along way into a successful nutrition plan.
For Ironman a concentrated bottle is an option though you’d want to take water hand offs so you can dilute it properly so its absorbed. Carrying a liquid shot flask is also an option as this gives you 400 calories in a small container. Lastly make sure to take advantage of your special needs. Take a look at our athlete section on the website where you can read Ironman nutrition plans from all of our Pro’s.
Not sure your bike set up, I ride with a shiv s-works where hydration in frame and I can put up to 650ml water which I mix with efs pro. Then I have a single water bottle behind seat with a combination of 100ml water / 2.5 scoops efs pro / 35ml efs shot then i repeat that mix based on my ride time, so let’s say I do 180km bike in 6 hours and consume 650ml liquid per 1h30, I need 3x100ml combination in the bottle, when I come to water points I grab water top my hydration sack and squirt 100 ml combo in .
I have carried powder form in plastic sachets but it’s messy and takes up space for bars etc , hope that helps and apologies for metric I come from South Africa where metric is our measuring system
Ian,
Its no problem making a bottle that is very concentrated and has all the calories and electrolytes you need for the entire ride. You will have to grab additional water to make sure you then dilute the concentration down to the correct level. Many athletes will make sure their 1st bottle is mixed at the correct concentration and the 2nd bottle is highly concentrated. After finishing the 1st bottle, they replace it with on-course water and then alternate between the remaining bottle and water.