Fluid & Electrolytes 101: Recommendations from the Trail and Medical Tent

By Lisa S. Bliss, MD

Maintaining fluid and electrolyte balance during the Western States Run seems to come naturally to many runners. They just eat and drink and run and are merry. For others, it’s not so easy. They eat and drink and slosh and puke and lose and gain weight and become sick and confused about what they are doing “wrong” and, even more, what they should do to better their situation so that they can make it to the finish line in one piece. I will attempt to answer some common questions that come up in training for and participating in the Run. I must first toss in the important disclaimers that 1) fluid and electrolyte balance is far more an individual art than a science, 2) what works for one person might not work for another, and 3) knowing what works best for you in practice is the most important way to answer these common questions. There is no substitute for trial and error, practice and experience! That said, here are some answers to the questions I frequently hear.

My weight is down and I feel fine. Should I do anything special? Weight is the simplest indicator of hydration status available to runners in training and on the course. Some weight loss during WS is expected and acceptable. In general, 2% weight loss is considered “acceptable.” All things being equal, if you are down 2% of your weight, you can drink a little (1 pint fluids = 1 pound weight OR 1 liter fluids = 1 kg weight) and get your weight back up. No big deal. The concern in longer arduous runs like Western States is that, well, you have to run 100 miles, so an early trend towards dehydration, if not turned around, could mean that you will continue to lose weight during the run, putting yourself eventually at risk of dehydration further down the trail. At WS, we like to have runners stay close to their starting weight, not more, not too much less, simply because you have a long, long way to go. Even as little as 3% weight loss can affect performance by putting strain on the body’s cardiovascular system. Additionally, staying hydrated will keep muscle breakdown materials (myoglobin) flushing through the kidneys. So, if your weight is down and you feel good, just slightly increase your fluids and continue on your way down the trail.

My weight is down and I’m puking? How can I stop puking? This is a little trickier. For some, puking is a common part of their ultra experience. Certainly, the stomach can simply rebel, and getting rid of all the stuff that’s been sloshing around in there can be liberating. Many runners say they feel much better after puking and can “start anew” with fluid and calorie replacement without any problems. Puking, in that sense, seems to be part of the solution to a problem. But what if puking is the problem itself? What if it can’t be stopped, and despite an ultra effort, calories and fluids refuse to be absorbed from the gut and you become more and more dehydrated and fatigued? In this case, the runner should stop or walk and let the body rest because the body needs that fuel to propel it down the trail. You must let your gut recover. As you know, running an ultra is stressful on the body….way more stressful than many even think they know it to be. When you place demands on your muscles to keep moving you forward, the blood in your body gets “shunted” to those muscles to fuel them with the oxygen they need to work. And if the muscles are hogging the blood, then some other parts of the body must be sacrificed at the expense of the muscles. Unfortunately, the gut is often sacrificed. And if you keep shoving precious fluids and calories into a gut that cannot absorb them, then they have to go somewhere, and they may come back up and out. So, if your weight is down and you cannot keep fluid and calories down, then you must slow down or stop – decrease the work of the muscles and let the blood get back to the gut so that it can work and absorb like it’s supposed to. Unless you can run without fluids or calories (not recommended at WS!), this is your best bet for remedying the problem. Remember too that heat can exacerbate this problem. That’s because much of the body’s blood is also “shunted” to the skin to facilitate sweating and thus cooling, leaving even less for the muscles and gut. So, if the body is hot and you are sweating profusely and your weight is down and you cannot stop puking, you must cool down your body first. When running in the heat (and you are likely to encounter some in the Canyons), Ice is Nice! Dousing your head and trunk with water also aids in cooling. Cool the body first, then try to resume fluids and calories. Some tricks worth trying (which may not overwhelm the gut while you are slowing down and letting the blood redistribute back to the gut) are sucking on ice or hard candy, and sampling other simple calories like gels that don’t require significant processing by the gut. Some runners find that ginger in various forms can be helpful as well.

My weight is up and I feel fine. Is that OK? Weight gain is fluid gain. You can acquire too much fluid by too much input (drinking) or not enough output (e.g. low sweat rate in slow runners or in cooler temps, or not peeing out the extra because of ADH) or both. I repeat: weight gain is fluid gain. The weight of salt is obviously negligible. There is also some contribution from foods, but the dry weight of food is not the primary reason for weight gain. If your weight is up, think fluid, not salt. Sure, it is true that salt can cause you to retain fluid if you take too much, but weight gain reflects the amount of fluid on board and therefore it is the fluid that must go if you are gaining weight. Cutting salt while continuing to drink will not solve the weight gain problem (even if you have “overdone it” on the salt). Similarly, adding salt to an already fluid overload problem will not solve the weight gain problem. This will only cause an overload of both, which is difficult to remedy. The ONLY way to solve the weight gain problem is to get rid of the extra fluid. So, if your weight is up, the most important question to ask yourself is, What should I do with my fluids? Try to keep it simple. That said, what holds true for weight loss also holds true for weight gain: a little weight gain is usually not harmful – IF you feel fine. Still, in that case, you definitely should decrease your fluid intake so that your weight is down by the next medical check. Do NOT continue the same rate of fluid intake because, well, it’s too much!

Always remember that if your weight is up, you are in NO WAY in danger of dehydration; you are, in fact, overhydrated. So, decrease the fluids and get your weight back down. If you are feeling fine and urinating fine, then simply decrease your fluid intake and reassess at the next medical check. If you are feeling fine but you are NOT urinating, then the situation is a bit more precarious. That’s because if you keep drinking and sweating at the same rate, and you are not eliminating those excess fluids, your weight will go up quicker and you are putting yourself at risk of the dangerous, much talked about, fluid overload hyponatremia, where your sodium literally drops too low from getting diluted in the blood. So, remember, just because you are feeling fine at one point doesn’t mean you will be feeling fine down the trail. Take care of the little things as they come up, make small adjustments early, and prevent problems down the trail.

So how much is “a little weight gain?” Dang! I wish you didn’t ask me that! That’s a tough one to answer. Let me just say that it depends on how you feel. If you run into Michigan Bluff and your weight is up 3% and you’re feeling great – with NO problems – then you should follow the advice of “continue on but decrease your rate of fluid intake so that your weight is back down at the next medical check.” If, however, you stumble into MB and your weight is up only 2% but you are NOT feeling fine, and you have symptoms of hyponatremia (including headache, nausea, vomiting, dizziness, lack of coordination….think “intoxication”), then that “little” amount of weight gain for you IS harmful and you should stop drinking and follow the directions of the aid station personnel. This doesn’t necessarily mean your race is over, but if you don’t take care of the problem, it certainly may be!

The bottom line is, if you are overweight and feeling fine, decrease your intake and get your weight back down. Take care of it early to prevent trouble later, and beware of repeating the same thing later in the Race! Remember that one way to lose fluids from the body at WS is through sweating. Sweat rate also increases with a faster pace, and decreases with a slower pace. That may seem obvious but there are a lot of runners who believe if they are slower and “out there longer” that they are more likely to get dehydrated. Reality is, these runners not only sweat less, they also have more time to drink. They are actually at a greater risk of becoming fluid-overloaded. Also, smaller body types have less room for error when it comes to maintaining a proper sodium concentration in the body. So, smaller folks are also more at risk of getting fluid overloaded, just because it is easier – based on total body water – to do so. Note that a runner does not have to gain weight to develop hyponatremia. One can be dehydrated and still get it. This usually occurs in faster runners who sweat out a lot of fluid and electrolytes and inadequately replace both. Symptoms are similar in either setting.

My weight is up and I feel horrible! What should I do? Simple. First, stop drinking. Second, pee. Putting more fluids (including electrolyte drink) into an already fluid overloaded body that feels shitty is asking for trouble. So, no water, Gatorade, GU2O or even IV fluids! The only acceptable thing to imbibe is a concentrated sodium mixture, like 4 bouillon cubes mixed in 4 oz of water or soup broth with an extra bouillon cube or two mixed in. The goal is to get a little sodium while NOT adding extra fluids. Salty foods are ok too. BUT, that’s just the initial step. You are not cured just by doing this! You should not continue down the trail doing the same thing and expect different results, i.e. to feel better. Depending on how you feel (or how you present to the medical personnel), more needs to be done….and peeing is key. You must rid your body of the extra fluids. And sometimes this is the toughest part of running an ultra….making yourself pee off extra fluids when your weight is up and you feel shitty. Continue on….

My weight is up and I can’t pee. So now what should I do? Under “normal” conditions, if you drink too much, you simply pee it out. However, there is not much “normalcy” in running a 100- mile race through elevation, temperature, and diurnal changes! Running WS puts your body under a great deal of stress. One of the body’s common reactions to stress is the secretion of a hormone called ADH (Anti-Diuretic Hormone). Remember that a diuretic (like coffee) causes you to urinate more. So, an anti-diuretic causes you to urinate less or not at all, depending on the level of the hormone in your body. Under “normal” conditions, if you drink a lot of fluids, ADH is suppressed, and this cues the kidney to “diurese,” i.e. pee out the extra fluid. However, under stressful conditions, sometimes ADH is inappropriately released and it causes the kidney to hold on to the urine. It is an inappropriate release because if you are fluid overloaded, ADH should not be hanging around inhibiting your kidney from dumping that extra fluid. This ADH is often the nemesis of the ultrarunner that can’t pee. (Note that moderate dehydration will also cause the kidney to hold onto urine too….Argh! It gets complicated, I know!). The key here though, is that if your weight is up and yet you can’t pee off those extra fluids, ADH is the likely culprit. So, what should you do in this situation? Well, these are the things you run across at ultras that can cause ADH to be released even when you don’t want it around (like when your weight is up and you need to pee off the extra fluids): nausea, stress, and hypoxia (elevation). There is LOTS of anecdotal evidence that decreasing the stress load on your body can help the body to “relax” and get rid of that inappropriate ADH hormone and thus allow the kidneys to urinate. Decreasing stress at WS may seem impossible, but there are definitely things you can do. Slowing down or walking is a good place to start. Cooling down if hot is also helpful. By decreasing the stress on the body and allowing the body to get rid of the ADH, you will eventually see (or hear or feel) the flood gates open and your kidneys will dump that extra fluid. Slowing down and cooling down are likely some of the reasons why runners tend to diurese during the night portion of the run.

How much salt should I take and how can I monitor it? If you chose to supplement with salt, you must practice this in training. Every runner is different with regards to salt intake during ultras. Some runners take no supplements and get some sodium with the foods and drinks. Others prefer to drink water or sports drink and take salt supplements so that they can better regulate their intake. There is no right or wrong way. In an ultra, sodium is primarily lost in sweat. It can also be lost with vomiting or diarrhea. It is also excreted in the urine. Some researchers say that all sodium lost in sweat should be replaced; others say it does not need to be replaced at all (at least in shorter, “easier” runs). Many ultrarunners swear that supplementing with salt during the Run is helpful or even necessary. For now, I will side with the experience of the ultra masses that encourages some sodium intake whether by supplementation or salty foods. For the average runner: Sweat rate averages between 1.0 and 2.5 liters/hour. Some runners sweat more, some less. When heat trained, sweat rate increases (you sweat sooner and more), and the sodium in your sweat decreases (the body conserves sodium). Sweat rate also increases with a faster pace, and decreases with a slower pace. Average sweat sodium loss per liter of sweat is between 900 mg and 1400 mg. Some lose less, some much more. For a mental picture of how much sodium that is, 1 teaspoon of table salt (NaCl) has about 2300 mg of sodium (Na) in it. The amount of liters of sweat per hour can be determined by weighing nekkid before and after running…though I warn you that sweat rate for the same runner may vary tremendously over the course of 100-mile race. So, while it may seem like it comes down to just math, numbers are really just general guidelines and if, followed too strictly, can get you into trouble. There are just too many variables, not only from ultra to ultra, but within one race too (affected by training, changes in pace, altitude, food, temperature, etc.).

Still, the best *general* recommendation I have found is to supplement with about 300 mg to 1000 mg per hour. It doesn’t matter how you get it, whether it’s through sodium supplements or from the diet. This amount may not replace all the sodium lost in sweat, but we don’t know if a runner NEEDS to replace ALL the lost sodium for optimal results. So, nothing replaces your own experience. And remember, do not make drastic changes on Race Day! Also know that not all supplements are created equal! Succeed! Caps contain 341 mg sodium each, Thermo Tabs contain 160 mg sodium, and Hammer e-caps contain 40 mg sodium (the label says 100 mg of sodium chloride NaCl, but NaCl is only 40% sodium by weight). All that said, I know there are many runners that do very well with lower sodium amounts than what I state here. That is fabulous. There is no right answer. You should do whatever works for you.

I’m getting muscle cramps. What should I do? There are two main theories on muscle cramping. The first is that they are due to neuromuscular fatigue and the second is that they are due to electrolyte depletion and dehydration. The best thing to do for muscle cramping is to try to prevent them in the first place. Nothing substitutes for training. Specifically trained muscles will be adapted to the tough conditions at WS. Sometimes, however, cramps are unavoidable. So, if cramping occurs in one muscle like the calf, for instance, then you should do a prolonged stretch of that muscle until the cramping subsides, repeating as necessary. If you have multiple muscles cramping or cramping more proximally, like in the quads, you should assess your fluid and electrolyte status. Is your weight too low or too high? Both may contribute to more diffuse cramping due to dehydration or sodium depletion respectively. Some experienced runners take extra sodium or potassium to help with cramping. It is worth a try! Still, the best advice to try to avoid cramping may be to train specifically for the Race.

Will I know if I am getting heat stroke? Heat stroke is a medical emergency. It can come on quickly but there are usually warning signs. It does not have to be 90 or 100 degrees Fahrenheit for heat stroke to occur; it has been known to occur even in the 60s. You must prevent heat illness and know how to treat it quickly if you suspect it. Know that the body’s muscles create an enormous amount of heat. Harder working muscles create more heat, so faster runners generate more heat than slower runners. That heat must be expelled from the body. Heat accumulates in the body when heat production exceeds heat loss. Slowing the pace is one way to decrease heat production. The evaporation of sweat from the body is one way to increase heat loss. Sweat does not evaporate as well in humid environments, so humidity increases the risk of heat illness if other factors (like speed) are not modified. Things to look for: feeling overheated, profuse sweating, and flushed skin as the body shunts blood to the skin in effort to promote sweating, headache, nausea, vomiting as the gut shuts down at the expense of blood being shunted to the skin. If any of these are present, start cooling your body by dousing with cold water and start generating less heat by slowing down or stopping. Ice wrapped around the neck is a very efficient way to help cool the blood as it makes its way to the brain. Consider buying a WS Ice Cap or Ice Bandana! These are priceless in the heat!

Scarier symptoms of heat illness include dizziness, confusion, and irritability. Any of these symptoms should prompt a medical evaluation. Sure, some runners get irritable without having heat stroke or another serious medical condition, but an evaluation is necessary. Listen to the concerns of other runners, family, or medical personnel. Because some conditions cause confusion, others may be more aware of the danger signs than you! Ice application is the easiest first line treatment. Place ice packs in areas of major arteries – around the neck, in the arm pits and over the femoral arteries in the groin region. Never assume that an oral temperature accurately measures the core temperature! The only accurate core temperature measurement available at WS is a rectal temperature. So, please, take heed, and when heat illness is suspected or even in question, just start cooling the body!

What if I get dizzy when I stop running? What should I do? This is very common and is likely due to postural hypotension. That is, your legs have been working to pump the blood back up and through the body for hours. When you stop, you suddenly take away that pump and the blood can, in a sense, pool in the legs, causing you to feel faint. The best solution….keep running! Or at least, keep moving. However, if you need to stop and cannot keep moving, pump your feet and march a bit in place, and that will help keep the blood circulating up towards your head. If that is not successful and you feel too dizzy and fear you may fall or pass out, then lay down before that happens….or else your body will do it for you! A few minutes of elevating your feet (and even hips) will utilize gravity to get the blood to your head. The dizziness should subside fairly quickly in this position. If it doesn’t or you are concerned, seek medical attention. Dizziness (and even passing out) can happen after finishing the Run, even up to an hour after finishing! It happens for the same reason – you’ve turned off the pumps in your legs. Again, the best thing to do is to keep moving. BUT if you are taking a well-deserved break by sitting or lying down, it is prudent to “pump” your feet and legs to get the blood moving before standing up. It can take some time for your body to adjust to your legs not moving, so it’s good to be aware that this can happen, and that it is in fact, fairly common. Also know that dehydration has nothing to do with this kind of postural hypotension. Symptoms should resolve with lying down with your legs up. It may take several minutes or even an hour before the dizziness resolves upon standing. If you or someone you love has any concerns whatsoever, seek out medical personnel.

What if I get dizzy and lightheaded when I’m running or walking? What should I do? This is more serious than the above scenario. If you are dizzy or lightheaded on the course, the first thing to consider is your blood sugar level. If that drops too low, you can be overwhelmed with fatigue and can become light-headed and even your mood can change drastically. A secret handed down from one of the best ultrarunners around is to always carry some simple sugar with you, like some hard candy or similar. This is the time to indulge in that sugar! If low blood sugar is indeed the cause of your symptoms, then you will notice a dramatic recovery. If that is the case, get yourself to the aid station and fill up your tank enough so that it doesn’t happen again. Cokes and 7-ups have plenty of sugars too and will perk you up. If, after trying sugar, the dizziness and lightheadedness continues, you should seek medical attention. It could be due to a number of things, including heat illness, hyponatremia, even a problem with your heart. It could also be due to simple fatigue, but in any case, you should err on the side of caution and get checked out. Even dizziness from fatigue alone is hazardous on the trail. The opportunities for falling are many, and that alone, can be very dangerous.

Some final musings. Peer pressure: Some runners will literally drown in the amount of fluids that other runners require. In general — but not always — women tend to require less fluid than men. They tend to have lower body weight and perhaps we really do not sweat as much in general. It seems that they also tend to get in a little more trouble with ADH. Perhaps there’s a hormonal reason for that. Probably. But it hasn’t be proved yet. So, no matter your gender or what the issue, don’t do something based on what works for someone else. Do what works for you!

Swelling: It could mean too much fluid or too much salt or too much of both, or it could just happen from arm swinging or just because it does. Finger swelling is not a very reliable indicator of fluid or sodium status. Generalized swelling, however, including the wrists and forearms, is more likely to indicate fluid overload.

Spitting: The convenient and inexpensive Spit Test is a good test of hydration status. If you can easily work up a spit, chances are, you are well-hydrated!

Finally, I must conclude with some Psych content. We are, after all, biopsychosocial organisms! More often than not, problems that arise during your Run at WS can be addressed and remedied. Awareness is the first step in addressing a potential problem. After spending months of physical and mental preparation for the Run, it can be difficult to accept that sometimes things occur during the Run that require acceptance and adjustment. Listen to your body. The goal of the Staff at WS is to get you SAFELY to the finish line. They want that as much as you and will do their best to help you achieve your goal. However, safety is foremost. So, be prepared, know your body, train smart, arrive uninjured, run wisely, adjust as necessary, and arrive safely at the Finish to celebrate your monumental achievement!