Even in very hot conditions, most of the heat is generated by your body, which is only about 25% efficient. For every four calories you burn, only one calorie provides energy to move you forward—and the other three calories produce heat. That heat must be dissipated from your body through primarily by sweat. Your body is like a car’s radiator. Blood circulates through your core, heats up and circulates to the skin where heat is dissipated via sweat.
How Much Do You Sweat?
On average if you are riding in moderate conditions—that is, you aren’t gaining heat from the environment—each hour you’ll produce 600 to 800 ml (21 to 27 fl. oz.) of sweat! Each hour you sweat out almost as much fluid as contained in one standard (about 24 oz.) water bottle! If you push the pace a little, are climbing, are riding in hot weather or you are a larger rider, you could easily produce 32 fl. oz. (1 quart or liter) or more of sweat per hour.
Your personal sweat rate depends on: your fitness; how hard you are riding; the ambient conditions; and the variability among individuals.
Electrolyte Concentration per Liter (Quart) of Sweat
On average here’s what is in a liter or quart of sweat:
- Sodium: 800 mg / Liter (Quart)
- Chloride 1,065 mg
- Potassium 115 mg
- Calcium 40 mg
- Magnesium 19 mg
Daily Recommended Intake (DRI)
Let’s compare the amounts of the different electrolytes in sweat to the DRI:
- Sodium: DRI 1,500 mg or for athletes >1,500 mg up to 10g. Good sources of sodium include table salt, tomato & vegetable juice, pretzels, crackers, beef jerky, deli meat, cheese, dill pickles, pizza, soups, pasta sauces, canned vegetables, most fast food.
- Chloride: DRI 2,300 mg or for athletes >2,300 mg to match sweat losses. Good sources are the same as for sodium.
- Potassium: 4,700 mg or for athletes 4,700 mg or more with heavy sweat losses. Good sources include dairy (white & chocolate milk, yogurt), fruit (banana, pear, orange & orange juice, raisins, cantaloupe), vegetables (baked white & sweet potato, tomato & vegetable juice, corn, zucchini, avocado, carrots), dark chocolate.
- Calcium: 1,000 mg or for athletes 1,300 – 1,500 mg. Good sources include dairy (milk, yogurt, cheese, cottage cheese), dark leafy greens (spinach, kale, turnips, and collard greens, fortified cereals (Total, Raisin Bran, Corn Flakes), fortified orange juice, enriched breads, grains, and waffles
- Magnesium: males 420 mg, females 320 mg or for athletes 400 – 450 mg if from food or 350 mg if from supplements. Good sources include dark leafy greens (spinach, kale, Swiss chard), nuts (squash & pumpkin seeds, sesame seeds, Brazil nuts, almonds, cashews, mixed nuts), fish (halibut, mackerel, turbot), beans, banana, brown rice, quinoa, avocado, dried fruit (figs, prunes).
(Benardot, Dan, Ph. D, RD. (2012) Advanced Sports Nutrition, 2nd ed. Human Kinetics, Champaign, IL)
Note that a liter of sweat contains only 2.5% of the recommended intake of potassium, 4% of the recommended intake of calcium and magnesium only 4.5 – 6% of the recommended intake of magnesium.
Unless your diet is terrible or you are doing an ultra event sodium and chloride and perhaps potassium are the only electrolytes you really need.
Aren’t Electrolytes Important to Prevent Cramps?
Scientists have two general theories:
- Neuromuscular fatigue meaning that after all of those contractions your nerves fatigue. They send signals to the muscles that because of fatigue the muscles are at risk of injury and that the muscles should just contract and freeze to protect them from injury, i.e., you cramp.
- Sodium depletion
How Much Electrolytes Do You Need?
According to the American College of Sports Medicine (ACSM) if your ride is less than four hours, you probably don’t need to supplement with electrolytes unless your jersey is caked with salt or you cramp. Sodium depletion may be one of the causes of cramps, so if you suffer from cramps try supplementing with sodium.
If your ride is longer than four hours, then additional sodium and potassium are recommended.
Electrolyte Replacement Drinks
Here’s what the ACSM recommends for a sports drink per 8 fl. oz.:
- Calories 48 – 96.
- Sodium 120 – 170 mg.
- Potassium 19 – 46 mg.
Here are several representative examples of commercial drinks. If your drink isn’t here read the label on the bottle. Per 8 fl. oz. (same size as ASCM recommendation)
- Gatorade – 50 calories, 110 mg sodium, 25 mg potassium – 7 servings to equal sodium lost in 1 qt. of sweat
- Powerade – 56 calories, 100 mg sodium, 30 mg potassium – 8 servings to equal sodium lost in 1 qt. of sweat.
- Heed – 104 calories, 40 mg sodium, 25 mg potassium – 20 servings to equal sodium lost in 1 qt. of sweat
- Skratch – 40 calories, 140 mg sodium, 20 mg potassium – 6 servings to equal sodium lost in 1 qt. of sweat
A few alternatives from the mini-mart:
- V-8 – 50 calories, 420 mg sodium, 470 mg potassium – 2 servings to equal sodium lost in 1 qt. of sweat.
- Low-fat milk – 100 calories, 125 mg sodium, 470 mg potassium – 6 servings to equal sodium lost in 1 qt. sweat
- Low-fat chocolate milk – 160 calories, 380 mg sodium, 425 mg potassium – 2 servings to equal sodium lost in 1 qt. of sweat
Sports drinks are deficient in sodium. If you choose to drink one because it provides calories, you like the taste and it’s convenient, then on rides over four hours (and shorter rides if you’re prone to cramping) you should supplement it to obtain more sodium.
Supplements, including electrolyte supplements, are a multi-million dollar business. However, the body absorbs minerals much more readily from food than from pills. For example, certain forms of calcium can only be absorbed with food. In general, if your diet provides sufficient minerals, then you don’t need to take supplements. If you choose to use a supplement, look for one with high sodium content, since that is the primary mineral lost in sweat.
Here are several representative examples of commercial drinks. If your supplement isn’t here read the label on the bottle. Per tablet
- Nuun – 360 mg sodium, 100 mg potassium – 2 tablets to equal sodium lost in 1 qt. of sweat
- Succeed S caps – 341 mg sodium, 21 mg potassium – 2 tablets to equal sodium lost in 1 qt. of sweat
- Endurolytes – 40 mg sodium, 25 mg potassium – 20 tablets to equal sodium lost in 1 qt. of sweat.
- Endurolytes Extreme – 120 mg sodium, 75 mg potassium – 7 tablets to equal sodium lost in 1 qt. of sweat
- Thermotabs salt tablets – 184 mg sodium, no potassium – 4 tablets to equal sodium lost in 1 qt. of sweat.
A few alternatives from the mini-mart:
- Subway 6” turkey sandwich – 280 calories, 760 mg sodium, no potassium
- Pretzels, 1 oz. 90 calories, 385 mg sodium, 41 mg potassium
- Wheat Thins, 1 oz. – 127 calories, 225 mg sodium, 59 mg potassium
When you’re shopping at a mini-mart read the label to see if it has what you need.
A Better Solution
Here’s the homemade sports drink I use, which meets the ACSM recommendations. Many of my clients have used this successfully. To make 1 quart:
- 1/3 cup (80 ml) orange juice
- 12 teaspoons sugar (adjust to taste)
- ¼ teaspoon salt
- Water to make 1 qt.
8 fl. oz. provides 100 calories, 150 mg sodium, 80 mg potassium. One quart makes four 8 fl. oz. servings.
(Yes, REALLY 12 teaspoons of sugar per quart. A single 12 ounce can of Coke has 9.75 teaspoons of sugar, for comparison.)
More Information on Riding in the Heat:
Get my 2-article bundle Cycling in the Heat
- Part one – Ride Management (20 pages) covers the effects of overheating, how to acclimate, now to train in hot months, what to wear in the heat, what to eat and drink in the heat, how to cool down if you overheat and heat-related problems.
- Part two – Hydration Management (21 pages) covers how to develop a personal hydration plan including assessing your sweat rate and how much you should drink, more on different types of electrolyte replacement and hydration related problems. The 41-page Cycling in the Heat bundle is $8.98.
Coach John Hughes earned coaching certifications from USA Cycling and the National Strength and Conditioning Association. John’s cycling career includes course records in the Boston-Montreal-Boston 1200-km randonnée and the Furnace Creek 508, a Race Across AMerica (RAAM) qualifier. He has ridden solo RAAM twice and is a 5-time finisher of the 1200-km Paris-Brest-Paris. He has written over 40 eBooks and eArticles on cycling training and nutrition, available in RBR’s eBookstore at Coach John Hughes. Click to read John’s full bio.
While I’m a fan of diluted OJ, isn’t it also a known diuretic? And do folks with fructose sensitivity have any issues with it?
For sodium & carbs, I find roasted corn snacks both convenient and palatable.
Coach Hughes says
No OJ isn’t a diuretic. You drink OJ, you pee because you’ve consumed fluid Yes if someone is sensitive to fructose then OJ, etc. would be a problem.
Roaster corn snacks – all kinds of snack food are good for sodium and carbs although some are high in fat.
Marsha Thurston says
My issue with OJ is that it didn’t last very long in a water bottle in the heat. I needed to carry Emergency Juice, in the sealed box-containers, and refresh my supply as required.
Marsha Thurston says
The list doesn’t include my favorite, everyday electrolyte drink — Propel water. It’s got everything except the calories, but I’d rather eat real food. Plus it’s water, so it doesn’t stain the inside of your Camelbak or water bottle and is easier to clean. Comes in both liquid and powder form.
Coach Hughes says
8 fl. oz. of Propel contains only 5 mg of sodium so it’s no better than water at providing electrolytes.
Mike Tierney says
I used the recipe from John’s downloadable e-articles. I tweaked the above recipe slightly (maybe to what John’s e-articles said at the time) –
Some juice for flavor (1″?)
Glucose powder (available at bulk food stores)
No-Salt (for the potassium).
For rides that required more than two large pre-mixed bottles I would take extra doses of pre-mixed powder and carry it in single serving small plastic sandwich baggies.
Angie R says
You have to be extra careful with the No-salt since it is pure potassium chloride. I have used No-salt as well too to supplement potassium on long rides and ended up in the hospital once. The heart muscle is very sensitive to elevated potassium in your blood stream and the only way to eliminate excess potassium from your body is via the kidneys through the blood stream. I use liquid Elete to add to my water bottle or drink mix since that mishap. It has a good proportion of sodium chloride and potassium chloride and I have not had a problem since.
Oro Valley Dragonman says
One of my favorite electrolyte replacement drinks, Pocari Sweat, is difficult to find in the US, but, in my opinion, worth looking for. Made in Japan, you can get it through the Internet, but it is not inexpensive.
I first learned about it at an early ’80’s event, the Tecate-Ensanada Bike Ride. It was just being introduced and the company was handing it out to promote the product. Delicious! Despite the name, it has a very pleasant, clean, taste, and is not “soda pop sweet”, like a lot of replacements are.
Coach Hughes says
Pocari Sweat contains 120 mg of salt / 100 ml. = 282 mg of salt / 8 fl. oz. Salt is roughly 1/2 sodium and 1/2 chloride so 8 fl. oz. of Pocari Sweat contains 140 mg of sodium / 8 fl. oz., which is within the ACSM’s recommended 120 – 170 mg. of sodium / 8 fl. oz.
Thanks for the suggestion.
Kerry Irons says
On long rides, I get my salt from my food rather than from drinks. I used to use energy/electrolyte drinks but the bike got covered with sticky salt and if I needed water (wash hands after changing a flat, “treating” road rash) I had nothing. Now I add salt to my food (fig bars, mixed nuts, cookies) so I am consuming it regularly throughout the ride. I tailor the amount of salt (and I include lite-salt for potassium) depending on the weather forecast, but typically 1/2 tsp of table salt sprinkled in my food bag for a 7 hour ride. The amount of salt doesn’t make the food taste bad and it helps to keep you thirsty.
Coach Hughes says
Just using salt is great. I use salt tabs for convenience.
Bob Dobbs says
+1 for V8 and for Endurolytes. I am a big rider so I start the Endurolytes early in the summer heat to make sure I don’t cramp out.
And tell them you want lots of pickles at the Subway.
Joe Reylek says
I use this: https://www.youtube.com/watch?v=91kV0hJEEfU
Joe Reylek says
Interesting comparison. Both sugar laden. I would never use either of them: https://www.youtube.com/watch?v=KfLFFHnim7E
Greg Titus says
If you’re cramping is generalized (a rare condition), it could be from sodium depletion/dehydration. This is not likely for most cyclists under most conditions. If your cramping is localized (i.e., a calf or thigh muscle), then that’s due to neuromuscular fatigue and sodium intake will not affect it. Prolonged stretch-and-hold for the cramping muscle (for a full minute) will help relieve the cramping, then riding easier will help keep it from striking again on that ride.
Potassium is an intracellular electrolyte. If there is potassium depletion, it’ll take about 24 hours to replenish it. Supplementing with potassium during a ride is fruitless. You can get all you need from your diet, off the bike.
Thanks! My recent bonk was pain in every muscle in my body. Because of BP issues, I avoid salt, but now feel fairly certain my bonk was dehydration and probably not enough salt.
I completely disagree with your absolute statement that localized cramping will not be helped by sodium intake, or that stretching will stop it. I ride in the desert southwest, and have had a few instances of cramping during hard rides. I always try stretching first, but it rarely helps. EVERY time I have taken salt, the cramping went away completely relatively soon. The two times I did not have access to salt, the pain would not go away until I got some salt (both times, about an hour later).
As far as cramping being due to neuromuscular fatigue, that may be true in some cases, but it is far from absolute. Unmentioned in the article but something to know about, rhabdomyolysis is a serious condition that may feel like very bad cramps but can be serious or even life threatening, and does not even require particularly strenuous activity to trigger it.
Brian Nystrom says
I still use one of the original electrolyte replacements, developed by Bill Gookin in the 1970’s. Originally called “Gookinaid E.R.G” (Electrolye Replacement with Glucose), it’s now sold under the “Vitalyte” label. It’s a simple, highly-effective formula that costs a lot less than most other mixes on the market, especially if you buy it by the case. I’ve tried a few others over the years, buy have yet to find anything that works better and I like its somewhat subtle flavors.
With a potassium requirement of 4700 mg.
All of these are inadequate.
No recommendations for extreme heat and humidity? Where I live, in the summer it does not take 4 hours to sweat enough to need electrolytes, it takes about an hour or two. When the temp is in the mid to high 90’s and and the humidity is also in the 90’s you can not cool down via air, you sweat 10 times faster because your body isn’t cooling. My first year here I got really sick from not consuming enough nutrients after 3 hour rides. I thought the “normal” amount would be enough, it wasn’t.I’m 6ft, 190lbs and built like a linebacker so I sweat over a gallon an hour, my bottles hold only 50oz. I did some research and realized I needed much more electrolytes than recommended. I doubled my intake and my rides are happy now. I use EFS First Endurance as it has high level of salts and potassium. If you don’t get the needed nutrients via diet your body will start taking them from your bones and that is bad for cyclists as we have a low impact sport.
Neil Larson says
Thanks John, love this article! We are so well trained by marketing that most of us would prefer to buy (or perhaps “trust”) a commercial product., than make our own inexpensively. The replies above are a good example of this. Re your recipe – I’m not keen on orange juice – could I substitute blackcurrant juice instead?
Dustan Martin says
I like to put two small cans of juice in a water bottle, which fills it about half way. I also dump some salt in. Then fill the rest of the way with water. I haven’t found a bad juice yet. Grapefruit and pineapple juice works great, also grape juice. I like V8 but I have not tried that yet.
Coach Hughes says
Dustan any juice works, although some have more potassium than others
Jeff Den Herder says
Country Time Lemonade and salt or ‘lite’ salt which replaces some of the sodium with potassium does it for me!
Doug (Madison) Kirk says
Elete drops come in a tiny lightweight bottle. 1/2 teaspoon = 125 mg sodium and 130 mg potassium. That’s all that’s in it. On a multi-day tour it is nice to have the compactness of it. At home I’ll add a little lemon juice and sugar for taste.
Dennis Adam says
Myself and my wife have been using a home made drink similar to Coach Hughes, except we use agave syrup instead of sugar as it has a low glycemic value.