We have been having a heat wave here though - 103 in the shade. Kind of late, but otherwise the expected heat after months of cool, rainy weather that characterized the Amgen Tour of California. So now I am on the prowl for SWF - but not the kind you'd expect. In this case S.W.F is an acronym for
Salt, or more specifically, sodium, is needed to transport water (study the animation and read the remarks) into your blood, generate thirst, and is necessary in the small intestine to enable transport of glucose from the intestinal brush border into the bloodstream.
In addition, salt must be added to digested water to maintain the isotonic salinity of the blood, which just happens to be identical to seawater. Supporting glucose transfer doesn't use up sodium, but maintaining isotonic electrolyte levels in your blood does. Africans, and their descendants, are genetically predisposed to hang onto sodium tenaciously. It leads to might higher rates of hypertension, but on hot days, the brothers have an advantage!
As such, sodium, typically as sodium chloride (table salt), or sodium citrate (typical source in sports concoctions), is the foundation for proper hydration, which in turn is the foundation for proper nutrition. You will need between 400 and 1,200mg per hour, and maybe more, to keep up with losses on hot days. That's between 1/6th and 1/2 of a teaspoon. Easy numbers to remember, as you will burn 400-1,200 calories per hour to fuel your ride. Happy coincidence, and nothing more.
Sodium and water, as well as all the high GI ride fuels you eat during cycling events, are processed in about the first 40cm of the small intestine - at least if all goes well. When things don't go well, food and water are swept past the absorption/diffusion zone in the small intestine and into the large intestine where bacteria await their next meal, which they will ferment, causing nausea, gas, bloating and cramping. Worse, you'll be feeling weak at the same time because you don't have enough sodium to get water and glucose into your bloodstream.
The good news is - with one caveat - that your large intestine will absorb almost any water it is presented with, and it's more efficient at absorbing water than the small intestine. The caveat is, while the large intestine can absorb water, and some sodium at the same time, it is also tasked with ridding your body of a lot of toxic substances, some of which are minerals, and lack of water and some fresh fiber makes simultaneously absorbing sodium and dumping toxic minerals very difficult.
A little pre-ride planning can be very helpful in this regard, as squeaky clean bowels, with a little fresh fiber thrown in from say, fruit, will make your event ride go well, while stale poo will be full of toxins that will tend to get reabsorbed. In essence, fiber in your bowels will act as a sponge saturated with toxins that will poison you each time you hydrate.
I have endured this condition on several occasions and it absolutely saps your strength and makes you feel sick, weak, and lethargic, just when you expect you should be feeling strong. The RX is to eat enough healthy fiber on the ride to get clean FAST. Your energy will improve almost immediately.
A great practical remedy is to drink 8-16 oz of premium prune/plum juice after your evening meal the night before the ride. Not only will you start the day clean, but prune juice is packed with good minerals and a whopping 41mg of quality carbs per serving. During the ride things like watermelon, strawberries, and grapes, will keep things moving in a good direction. Citrucel and FiberCon also work, and will NOT ferment, but have no antioxidants. Still, a good thing to have in your arsenal.
Cliff Bars are a god-awful synthetic concoction masquerading as something 'natural'. They contain lots of brown rice syrup, a completely man-made substance that breaks down brown rice flour with heat, and enzymes from bacteria, to 'predigest' the rice for you in much the same way corn flour is turned into maltodextrin. More to the point, it is spiked with inulin to provide fiber.
Inulin is a creamy substance food mfgs love because the tongue perceives it as sweet and creamy, but it has no oil. It's fiber that's made from chicory, is IMPOSSIBLE for human beings to digest, but ferments very quickly in the large intestine. In short, it is the perfect recipe for massive doses of gas and bloating. Fruit fiber is the best, and mother nature has provided huge amounts in yummy packages, usually attendant with lots of antioxidants, so stick to fruit.
While we are slaying sacred cows, Hammer Endurolytes have so little sodium in them (40mg) that you'd have to ingest 59 of them just to meet your normal daily requirement of 2,360mg. Given that they have 330% of your RDA of vitamin B6 per casual, you'd be ingesting toxic amounts of of B6 in doing so.
I'm going to list the sodium content of some common sports concoctions below, but before I do I want to hit the SWF order again. A nice, even, steady, constant flow of sodium into your system lays a very solid foundation for the same in your hydration and nutrition.
For this reason I highly recommend time-released salt tablets. My favorite is ThermoTabs, and I have been using them for over 30 years. 1-2 an hour will keep you on a nice even keel. As always, your kidneys will filter out any excess.
On that note, there's a very practical way to determine how much sodium to ingest, increase the rate of ingestion until your kidneys start to hurt (low-mid back pain), and then back off a bit. The entire surface of your skin acts like a 3rd kidney, so excess salt is very quickly (15-30 minutes) removed.
Be aware that things like Gatorade have sodium, sugar and water together, which is fine until you have to ingest so much Gatorade to satisfy your water and sodium requirements that your small intestine can't digest the sugar fast enough to keep it out of your large intestine. The usual remedy, watering it down, deprives you of the sodium you need, so either add something like PowerBar Electrolytes to your mix, or take 1-3 ThermoTabs per hour.
Don't try to increase the strength of your Gatorade mix to get more sodium. It's not just salt that increases osmotic pressure. Sugar is used in canning fruit for exactly the same reason salt is used to cure meat - they both create high osmotic pressures to extract water. Your GI tract cannot work against this kind of pressure, and when osmotic pressures get high enough, water will actually be drawn out of your blood and into your gut. Very, very bad.
The remedy for avoiding high osmotic pressure due to excessive sugar, is to substitute starch, or it's chemically altered cousin, maltodextrin. (GU, Perpetuem, 50lb bags of the stuff from GPC in Iowa) In my experience short-grain, waxy Sushi rice will best any of these, and contains only small amounts of sugar if made as usual.
You should always monitor the color of your urine, but know that simply being able to urinate is not a reliable indicator that you're properly hydrated. If you're very low on sodium, your body will be forced to excrete water to keep you from going into a state of hyponatremia (low sodium). Thus, it's possible to be dehydrated, but still be urinating.
With intense heat, it's not VO2max, or muscular endurance, or glycogen depletion that limits athletic performance, its your body's ability to digest water fast enough to prevent dehydration causing the body to hoard the last of its water to maintain blood volume by arresting sweating, and closing capillaries, which leads to very high core temps, internal organ failure, brain damage, heart attack, and death.
The best way to recover from impending heat stroke is to cool the body without requiring sweating. This means pouring water down your back, over your head, or immersing yourself in water. Ice packs can help, as can cold drinks. Packing your thighs with ice is very good. Fans won't help. You've stopped sweating, so they won't help unless you have external water sources to power evaporative cooling.
The bottom line for sodium, is it's almost impossible to get too much, and very easy to get too little. More is almost always better. Salt, Water, Food.
- Morton's Salt: 590 mg per 1/4 tsp serving. 491 servings per $0.99 box
- 1 sausage link: 500-600mg
- 1 serving spaghetti sauce: 400-500mg
- Nuun 1 tablet serving 360mg (with an awkward 16oz of water)
- Succeed S-Caps: 341mg per capsule
- Gatorade powdered mix: 338 mg per 24oz cycling waterbottle or 450mg per 32oz quart
- Powerbar Electrolytes: 260mg per foil stick
- ThermoTabs: 180mg per time-released tablet
- 2 tsp salsa: 110mg
- 2 tsp peanut butter: 90mg
- Hammer Endurolytes: 40mg per capsule (lick your finger and poke a salted tray. Just as effective)