Near Death Dehydration

Allow me to take you back to the day I found myself so far past the limits of dehydration that it left me completely helpless - locked up, immobile, consciousness fading away, and on my way to the hospital for three IVs.

First you have dehydration and cramping, but I was at a level beyond what I thought possible. We were doing a five-hour ride across the island of Puerto Rico, and I spent the last hour cramping, trying to limp my way back to our end point. It came to a point where I felt the cramping coming to a head, so I rushed to a vacant house for their water spigot and fell off my bike crying in pain, yelling to my friend (Ryan) to get me water. Confused and shocked, he started knocking on the door, I cried “no! the spigot! water! please! hurry!”. My quads, calfs, core muscles, and arms all cramped so badly that I could not move, it was so painful and I could not escape it. I started to drink the water but I know that my excessive sodium loss required that I take in at least salt along with it to rehydrate. I started screaming to the neighbor who was outside to ask if he had salt, he did not speak english and Ryan ran over asking him for salt, also giving him hand signals for “salt” to try to translate. For someone who does not understand dehydration or fluid balance, they were probably wondering why I was laying on the ground in pain yelling for table salt. Ryan poured a bunch of salt in a water bottle and I began drinking the salt water, and I knew it was important to not drink plain water to avoid hyponatremia which is where the cells swell.
I was laying on a hot concrete driveway in the beating Puerto Rico sun and humidity, but the salt water seemed to be alleviating the extreme cramping. I got in a comfortable fetal position that subsided the cramping, but knew if I moved it would trigger another episode. Ryan wanted to carry me over to the neighbors house and get me in the AC, but I tried and told him it was a bad idea, and that I was starting to cramp again. I laid back down and continued drinking the salt water, asking Ryan to put his hydration pack under my arm to relieve the pressure on the concrete.
About 25 minutes had passed and I eventually decided I needed to get out of the sun as I was still overheating and sweating a ton on that driveway. Ryan helped walk me over to the house across the street which had shade in the driveway. The neighbors had asked if I need an ambulance but I suggested I think I’ll be okay if I try to rehydrate myself, so no ambulance was on the way yet.

When I got to the house across the street, I turned on their water spigot and tried to cool myself with it by laying on the grass underneath it, waiting for the water to turn cold (it never did). Ryan was a few meters away talking to the neighbor and then, something started to feel off. My body started cramping even worse than the first time and I lost complete function and control of my limbs, and my jaw began to tighten up making it hard to communicate. My fists were white knuckle tight and my legs were so cramped and locked out straight that I could not fight it, I had to let the cramps happen. I could barely talk and my fists were clenched so tight that I could not drink by myself. I mumbled to Ryan that I could not use my hands and that I needed him to feed me water. I couldn’t speak very loudly but I told Ryan “I need you to get an ambulance here now”. Ryan had to hold the water to my mouth for me to drink and I was feeling like I was going to pass out. All I could focus on was breathing deeply and slowly to try and keep my nervous system in a parasympathetic state. I wanted to scream and cry in pain but my body went into full survival mode. At this moment, I knew this was a lot more serious than I thought and it could be really bad.
I was completely locked up, stiff as a board, feeling shearing pain from the cramps, feeling sick to my stomach from all the salt water, feeling like I was going to pass out, I wanted to cry from how painful this was, but I was so stiff and out of it that I couldn’t. My body was shutting down, and I realized that this might be a very serious situation, and had the first thought that this could be it.
Eventually one of our team members showed up in a van and helped get me electrolyte drink mix, which has more than just sodium in it. They poured one into a bottle and filed it with water, I said “no! I need more, more mix!”. I yelled to Ryan and asked him to bend my left knee that was locked out to relieve the cramp, he was gritting his teeth putting every ounce of force he could into my leg over his knee to bend it, but he frustratingly said “I can’t! I’m trying! I can’t!”. THAT is how cramped my legs were.

The ambulance eventually showed up and they immediately administered a 500ml saline IV. Once I got to the hospital, they gave me two more saline bags and took a blood sample to test Creatinine, BUN, and CBC.

HOW DID THIS HAPPEN:

One key factor that caused this for me is that I sweat a very high concentration of sodium per liter of sweat. In 2023, I did a Precision Hydration sweat test which uses medical grade lab equipment to test sodium concentration in a persons sweat. It is called a Pilocarpine test which is used in the medical field to test newborns for cystic fibrosis which is a disorder of the sweat glands where the glands allow too much sodium to pass through to the skin during sweating, resulting in excessive sodium loss in sweat. The average athlete sweats around 1000mg of sodium per Liter of sweat, my test came back at 2,200mg of sodium per Liter of sweat, which is more than double the average.

On top of a high sweat sodium concentration, I tend to have a high sweat rate as well. A persons sweat rate during exercise depends on their physiological makeup, temperature, and their exercising intensity, and typically ranges 0.5-2.0L/h, but sweat rates can be as high as 5.0L/h as seen in American football players. The reason football players sweat this much is because they have disproportionately more muscle mass than they do skin surface area to dissipate heat, so they create heat at a greater rate than their bodies can get rid of it. I estimate that my sweat rate for this 5-hour ride that ended this way was at LEAST 2.0L/h, for a total sweat loss of 10L, which is 22.1 POUNDS of sweat, or a 13% loss in body water before hydrating. It is worth noting that my years racing ATVs led to slightly greater whole body lean muscle mass, which contributes to greater heat generation and a higher sweat rate in the heat, so I tend to run a little bit hotter.

I routinely test my sweat rate in training due to this fact and there is plenty of scientific evidence showing that a sweat loss of greater than 2% of your body weight can cause performance decline. This is primarily due to a decrease in extracellular fluid in which the cardiovascular system is part of, meaning blood volume decreases and stroke volume decreases along with it. A decrease in stroke volume causes the hart to beat faster every minute to keep up with the exercising oxygen and energy demand, so your heart rate increases for the same output, which is called decoupling. On training peaks this “decoupling” metric (Pw:Hr) is measured by comparing your HR and power in the first half of a workout versus the second half. We want to keep it less than 5% in most rides, in this case, I decoupled 26.2%.

During the ride I took in around 5.7L of fluid, resulting in a 4.3kg loss in body weight, only a 5.6% drop in total body weight. I took in roughly 600mg/h (3000mg total), which is only replacing 13.6% of what I was losing. Based on my testing, I lost 22,000mg of sodium which is more significant in terms of why cramping happened versus the fluid loss. Keep in mind that the blood contains about 3500mg of sodium per liter, and we have about 5L of blood, so our entire cardiovascular system has about 17,500mg of sodium in it. The body also stores sodium in the intersitial (extracelular) space, which is estimated we store around 1000mg/kg in total body sodium. At 77kg, I have about 77,000mg of sodium, so 22,000mg is 29% of this total body sodium.

The body VERY tightly regulates blood sodium concentration and aims to keep it around 135-145mmol/L. The hypothalamus has receptors that pick up blood sodium concentration and begins to make adjustments in the body with the use of hormones and drinking behavior to bring our fluid levels and concentration back into balance. It mainly uses antidiuretic hormone (ADH) to tell the kidneys to retain fluid and electrolytes or excrete them by lowering ADH. When we become dehydrated, our hypothalamus tells the pituitary to secrete antidiuretic hormone to tell the kidneys to retain fluids and salts within the body, and stops urine production. I knew that I was in rough shape, but I also considered that even being slightly out of this homeostatic range could cause severe issues, so I trusted that my body was shutting me down before more severe damage would occur.

While I was on this ride, clearly I was not consuming enough fluids or electrolytes to offset the losses I was incurring. I had also raced an XCO the day before and likely did not pay close enough to my rehydration so I started this ride dehydrated. Signs of starting a ride dehydrated include irritability, muscle soreness, and a higher RPE for your normal paces. A huge red flag looking back was that my kit accumulated some insane salt stains, and the significance of this is that we were exercising in the 90 degree 70%+ humidity of Puerto Rico, so why was my kit drying up? To me, this meant that my body stopped sweating, which is a sign of extremely low total body water, and a protective mechanism to make sure the heart and brain have the fluid and ion concentration they need for nourishment and survival.

The second sign was that I began cramping. These are not your normal cramps, but more like full on muscle contortions and cramping spasms. The two theories of muscle cramping are neuromuscular, which is suggested that when the muscles ecperience an effort they have never experienced before they cramp as a survival mechanism as the body fears cellular damage from a novel effort. The second theory and the one more applicable to my situation is the theory based on fluid and electrolyte imbalances or excessive/rapid fluid shifts. Understanding how fluid balance work in the body is vital to having a mental model of how water and ions move throughout the body to protect homeostasis, it is actually simple, but 99% of people don’t have this understanding.

I’ve been considering a third theory of muscle cramping, one that has to do with calcium overload and the concept of rigor mortis. When muscle breakdown occurs in the case of rhabdomyolysis (severe), the internals of the muscle cells explode out into the sarcoplasmic reticulum and encounters the neighboring cells. One thing inside of muscle cells is calcium, which when present in a muscle cell, tells it to contract…in this case without input from the nervous system which normally controls this. As the muscle contracts from this abundant and unsolicited calcium exposure, eventually the ATP demand cannot keep up. If you are already in a fatigued and depleted state, you may not have the energy reserves to make ATP anaerobically. If the ATP recycling cannot keep up with the demand, and calcium is flooding the system, you end up with a muscle that is “stuck” in the contracted position, as it requires ATP to relax a muscle in the same way it requires ATP to contract a muscle. (just some food for thought, but not proven when it comes to cramping).

Intracellular dehydration occurs when our extracellular fluid (ECF) excretes fluid and solutes to the points where the extracellular fluid concentration does not match the intracellular fluid (ICF) concentration. The cells respond by taking fluid out of themselves and putting it outside the cells to balance the osmolarity between the ECF and ICF. This can happen during exercise as we lose lots of fluid from the ECF from sweating, in which sodium (ions) go along with it. This can actually raise the ECF osmolarity which means the ICF has to donate fluid to balance the two out. When this happens, the cells shrink and become dehydrated which can alter their function.

Extracellular dehydration occurs when total fluid and ion concentration decreases out of the ECF, in which the osmolarity of the ICF and ECF remain the same. Since the osmolarity remains equal, the cells remain hydrated but the ECF fluid volume drops. Since our cardiovascular system is contained within our ECF, our blood volume drops, when our blood volume drops, our blood pressure drops, and when our blood pressure drops, the kidneys are not able to filter the amount of blood they need to for removing waste products. This lack of filtration by the kidneys can cause Acute Kidney Injury (AKI) due to excessive build up of waste products that the body does not like, primarily creatinine which is a byproduct of muscle metabolism from the Phospho-Creatine energy system.

The doctor told me that I was dehydrated enough to cause acute kidney damage, reflected by a creatinine level of 1.980mg/dL, where the normal range is 0.6-1.3mg/dL. He said it is not ideal for it to exceed 0.3mg/L above the high range. Creatinine is a byproduct of muscle metabolism from the breakdown of creatine. Usually the kidneys filter and excrete this byproduct, but in the case of this level of dehydration, the lack kidney filtration led to a marked increase. The doctors suggestion was to continue to hydrate and take care of myself.

SUMMARY:

Dehydration can be very serious, this was the worst case I have ever experienced, and I wouldn’t wish it on anyone. It was miserable. We have to respect the principle of individuality, and learn our own bodies unique needs to make informed training / racing decisions. In my case, I run hot in the heat, I sweat more than a normal athlete, and I sweat a lot more sodium per liter of sweat than the average person. This all adds up to making dehydration more of a risk for me in hot and humid temperatures.

Ride Stats:

Duration: 5.5 hours

Power: 203w (241 NP)

Calories Burned: 776cal/h (4,268cal total)

Sweat Rate: ~2.0L/h

Sweat Sodium Concentration: 2,200mg/L

Total Sweat Loss: 10L (22.1lb) (348oz) (2.7 gallons)

Total Sodium Loss: 22,000mg

Total % Body Weight Loss: 13%

Actual Body Weight Loss After Drinking: 5.6%

Consumed During the Ride:

Carbohydrates: 111g/h - 57% replacement rate

Sodium: 600mg/h - 13.6% replacement rate

Fluid: 1.2L/h - 60% replacement rate

Biggest Problems:

• Starting dehydrated from the race day prior (insufficient fluid and electrolyte intake post race). It is best to consume 100-150% of fluid losses combined with ~500-1000mg of sodium / L

• Not drinking enough fluid to stay within 3% body weight loss during the ride (Needed 8.0+L, I drank 5.7L)

• Not taking in enough sodium per hour during the ride, I would have benefitted from 1000-1500mg/h

• Not stopping when I started cramping, I needed lots of sodium and fluids to rebalance before I continued

• Doing a long hard ride in the heat the day after a race (I needed more time to recover)