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How to Fuel on HOT Days Using EFS Products

May 15, 2018 6 min read

How to Fuel on HOT Days Using EFS Products

How to Fuel on HOT Days Using EFS Products

by Robert Kunz MS | May 14, 2018

Training and racing in cold weather is significantly different than training and racing in hot weather, correspondingly your nutrition program needs to be adjusted to reflect these variations.

More specifically, you should pay close attention to how much you are sweating during hot weather training. In very arid environments (like in Arizona and Utah) your sweat can evaporate almost immediately, making some athletes under evaluate their sweat rates. It’s often in these environments that your sweat rate is, in fact, the highest even though you don’t necessarily see or feel moisture on your skin. In hot conditions, hydration (the consumption of water and electrolytes) trumps your calorie 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. Consider/ or analyze your hydration levels first and then add in the total amount of calories you can consume at that hydration level.

The Physiology

Sweat is your body’s mechanism to cool itself in hot environments. In fact, the more trained you are-the better your mechanism to sweat and cool yourself. If you have a high sweat rate, it’s a sign that you have good cooling. As you might guess, to maintain a high sweat rate, which is ultimately what you want in hot environments, you need significant amounts of fluid. A 1% drop in internal fluids requires your heart rate to increase in order to sustain an adequate sweat rate, obviously not what an athlete wants during exercise. Move to a 2% drop in your total internal fluids and the risk of heat exhaustion is significant along with a decrease in performance. You would likely be walking at this point or risking heat stroke. Furthermore, a drop in hydration reduces your ability to absorb calories and nutrients leading to further nutritional problems.

Appropriate hydration is critical to performance, particularly in hot environments. Even mild dehydration can cause the absorption of calories to become increasingly difficult which is why we recommend your nutrition plan take hydration levels into account prior to your caloric considerations.

What are the key variables to consider when training & racing in hot weather?

Athletes are notorious for first asking, “how many calories should I consume?” These same athletes focus heavily on calories and will consume gels to help reach their caloric target. They then consume water arbitrarily with no real thought to concentration percentage or osmolality. We suggest you flip this process upside down. First calculate your hydration needs and then add in the calories. Ask yourself, how much fluid can I consume per hour? Better yet, practice this to see what your maximum fluid intake looks like. Is it 24oz, 36oz?    In short distances you will likely not have a cramping, hydration challenge so it’s less critical to push the envelope of fluid intake. In a long hot session you will want to make absolutely certain you stay on top of your hydration and electrolytes to assure the final hours are as strong as the early hours. 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 that your training sessions in hot environments will likely be derailed by dehydration before it’s derailed by a nutrition bonk. Because nutrition absorption is highly compromised if it doesn’t occur with the correct amount of hydration it is paramount to focus first on hydration and second on calories. In extremely hot long sessions it’s not out of the question to push 40oz or 50oz per hour to sustain efforts, though many may get away with as little as 24-30oz. Do not consume more than 100 calories per 12oz of fluid. This is extremely critical to the success of your plan. Calorie concentrations greater than 100 calories to 12oz will hinder the absorption of fluid unless you have a drink that has a super low osmolality, such as EFS-PRO. Though five electrolytes should be consumed in order to remain in balance, we will recommend you look at sodium as the primary determinant of electrolyte intake since the body uses this mineral at a rate higher than the other electrolytes. Athletes should consume between 800 and 1600mg of sodium per hour with the vast majority doing well at about the 1,000mg level.


 Yips for dialing in your hot weather fueling with EFS products:  

EFS Drink:Designed to be used at an 8% solution (100 calories per 12oz). Contains an appropriate osmolality and concentration to be used daily in most situations. EFS delivers all five electrolytes (over 1100/mg per serving) at a level endurance athletes require to prevent cramping and dehydration and forceful muscle contraction. Contains Glutamine, Leucine, Iso-Leucine and Valine to help improve glycogen re-synthesis and reduce mental fatigue.

TIP:  Consume one serving 30-60 minutes before exercise and take one serving every 30 minutes during exercise. For additional calories and electrolytes use with EFS Liquid Shot.


EFS Liquid Shot: Designed to be used instead of gels. They can be diluted (with water) to meet your personal preference. EFS Liquid Shot is the perfect complement to EFS or EFS-PRO drink mixes for long distance training or racing in the heat.  Because Liquid Shot don’t contain any ‘gelling agents’ they won’t slow down absorption and digestion.

TIP: EFS Liquid Shots are ideal when you need more calories than you can get from drinking the EFS drink alone.  Not recommended as your primary or sole source of calories in hot conditions.


EFS-PRO DrinkEFS-Pro-Family:  Designed to be used at varying concentrations (80/120/160 calories per 12oz).  Additional nutrient technology helps shuttle electrolytes into working muscles and increases absorption rates in the most extreme conditions. Very high electrolyte content and low osmolality make it perfect for hot weather training or racing.

 TIP:  have 1 serving of EFS or EFS-PRO drink 30-60 minutes prior to exercise and then 1 serving every 30 minutes during exercise. EFS & EFS-PRO can be used as your daily fuel for training and racing in any condition. EFS-PRO is designed specically for extremely hot or extremely long racing. If you have a sensitive stomach, you should also consider upgrading to EFS-PRO.



-To ensure proper absorption of calories, forceful muscle contraction and maximal performance we recommend athletes first determine how much fluid they will consume. Use your total fluid consumption to determine how many calories can be absorbed. In hot conditions it’s recommended to consume 12oz fluid for each 100 calories. If you know you will only consume 24oz of fluid per hour, then your maximum calories will be 200. Attempting to force calories in without proper hydration is a recipe for gastric distress, cramping and poor performance.

< 2 hours HOT conditions:  When exercising less than two hours it’s unlikely you’ll experience considerable cramping or dehydration. Consume a serving of EFS or EFS-PRO for the 60 minutes prior to the workout.   Consume a 2nd serving of EFS or EFS-PRO during the workout session. 1-2 servings of EFS or EFS-PRO should suffice.


2-5 hours HOT conditions:  Hydration and electrolytes are paramount so try and determine your maximum hydration intake. Consume no more than 100 calories for each 12oz of fluid. Try to target a minimum 800mg of sodium per hour. EFS drink should suffice for most athletes in most situations. If you have a sensitive stomach or are prone to cramping, consider using EFS-PRO exclusively. A combination of these two products also works nicely.


>5 hours HOT conditions:  Hydration and electrolytes are critical so try and determine your maximum hydration intake. At these longer distances, you will also need to pay attention to your caloric intake and you will need to balance hydration and calories appropriately in order to sustain efforts. Only consume the maximum calories that can match your hydration consumption. Your effort will also be a determinant of how many calories you need whereas your total fluid consumption will determine how many calories will be properly absorbed. If the pace is slow, less calories are needed. If the pace is at threshold you will need more calories. EFS-PRO is recommended as your primary fuel/hydration drink for these long sessions in extreme conditions. EFS may work for many individuals, however EFS-PRO will work even better because of the special hydration technology and low-osmolality. In extremely long sessions, where additional calories are needed, EFS Liquid Shot is the ideal add-on supplement.

*NOTE:  in a single long workout where temperature or pace changes significantly your fuel should also change. If it starts out cold and heats up as the day progresses, make sure to adjust your fuel based on the above recommendations.

**Following every workout you should self-assess 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-PRO mixed in 12-20oz water works great.


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