Athletes, Electrolytes and Hydration 101 Part 2
Hey, have you heard that joke about hydration?? No? Of course not, hydration is no joke peeps. Everyone knows we are made up of mostly water. As humans, and as runners and triathletes we need water not only to survive, but to thrive. Lean athletes with more muscle mass will be made up of more water, as muscle has a much higher water content than fat. But no matter what your composition, we are basically water, surrounded by more water. The tricky thing about water that we tend to forget, is that we’re not just water, we’re electrolytes too, and both are crucial to an optimally functioning body. Electrolytes are necessary for moving the water in and out of our cells, as well as getting crucial nutrients, like glucose, into the cell. We have several electrolytes, but some of the big players are sodium (Na+), potassium (K+), calcium (Ca2+) and magnesium (Mg2+). A really basic overview is that sodium is in high concentrations outside of the cell, while potassium is at high concentrations inside of the cell and this interchange of ions is responsible for nerve function- and nerves tell muscles to contract. The muscle proteins actin and myosin rely on the electrolyte calcium to shorten and contract muscles and they rely on the electrolyte magnesium to relax them after a contraction. This maintenance of osmotic gradients affects the body in numerous ways, which we know includes nerve and muscle function as well as other crucial aspects, such as body pH. There are various mechanisms that keep the concentrations of our different electrolytes under tight control, including the Na+/K+ pump. We know that muscle tissue and neurons are both considered electric tissues of the body, and are activated by the electrolyte activity between the extracellular and intracellular fluid in which this pump plays a vital role. Without sufficient balance of these key electrolytes, muscle weakness or severe muscle contractions may occur.
Just a few of the key functions that water and electrolytes regulate are:
- Blood volume
- Blood pressure
- Movement of nutrients and waste
- Delaying cardiac creep/drift
No Spit, No Sweat, No Need To Go? Fix It All With H2O!
Our kidneys are a key player in fluid regulation. Ever run a race and realize after the fact that you didn’t urinate for hours afterwards? That was your kidneys hard at work, and a sign that your hydration needs some improvement. When your body detects that your blood volume is low, it will do everything in its power to help maintain blood pressure so it sends signals from the hypothalamus which tells you to drink water. ADH (antidiuretic hormone) is also released by the pituitary gland and tells the kidneys to recover water from the urine, which can also dilute blood plasma. So if you’re not getting in enough fluids, your body will do everything in its power try to keep the fluids you already have. This is another reason it’s crucial to stay hydrated, as hydration affects cardiac drift.
Cardiac drift is an increase in heart rate that occurs during prolonged endurance exercise with little or no change in workload.
As blood volume decreases from lack of fluids the heart has to work harder to pump out the same amount of blood, hence more beats per minute= elevated heart rate, which means you are working harder but moving slower.
Staying properly hydrated can delay cardiac drift from happening. It probably won’t prevent it completely but it will help keep it at bay longer and let you finish feeling healthy and strong.
No Need To Debate, When It’s Hot You Must Hydrate
This brings us to our next question, exactly how much water do you need? The answer, it depends. On a day you’re going about your normal routine you can keep track of your hydration levels by taking note of the color of your urine. If it’s completely clear, you might be over hydrating and creating an imbalance of electrolytes. If it’s pale yellow, similar to the color of straw, you are in the right zone. If your urine is darker than that, then you need to start hydrating right away. Keep in mind with this method though, that certain foods and vitamins can also affect urine color such as riboflavin (B2) which will make it bright yellow, and beets can give it a pinkish hue. Drinking alcohol will dehydrate you and deplete B vitamins so try minimize alcohol consumption in order to stay adequately hydrated. Ok, but what if you’re out training or want to know how much you should be taking in during a race or training? In that case, go to http://www.bonniekissinger.com/test-for-your-sweat-rate/ and follow the steps at the bottom of the page to calculate your sweat rate.
We know as athletes that we probably shouldn’t just be consuming water without also consuming sodium. So what happens when we don’t take in enough sodium? In a worst case scenario for the endurance athlete, you can end up with a condition called hyponatremia, which causes swelling that can be deadly. Some other things that can happen when you don’t consume enough sodium include increased heart rate(1), activation of the salt conserving hormonal system (renin and aldosterone)(2), the release of stress hormones adrenalin and noradrenalin and an increase of triglycerides in the blood(3). This can contribute to inflammation in the body. A sodium deficiency can also cause dizziness, fatigue, cramping, and muscle weakness.
Which brings us to our next question, exactly how much sodium do you need? Again the answer is, it depends. Are you a salty sweater? Are you exercising in the heat? Do you consume a lot of caffeinated products? All of these factors need to be taken into consideration. In a study of soccer players practicing in the heat (75-80℉) with roughly 50% relative humidity the players lost anywhere from 1.4 to 5.8g of salt (sodium chloride)(4). That’s a lot of variation. It is also worth noting that caffeine increases sodium loss in urine and in sweat. One cup of coffee can cause up to 437 mg of extra sodium excretion in the urine compared to placebo, and when the caffeine is upped, so is the sodium loss. 360 mg of caffeine can equal an additional 1200 mg of sodium lost through the urine(5).
A good starting place for figuring out what works for you as far as sodium consumption while training/racing is to start with roughly 750-1000 mg per hour. One teaspoon of salt (which is sodium and chloride) has around 2300 mg of sodium. This means slightly less than half a teaspoon of salt will put you somewhere around that 1,000 mg mark. A good quality salt like Redmond, Himalayan or Celtic sea salt can be used to do this.
You can also eat foods richer in sodium than others, such as celery, beets, broth, sardines and olives, which are nutrient dense and good to incorporate in your diet anyway. The one place we do NOT recommend getting your sodium from is processed foods. The sodium in processed foods usually comes paired with refined carbohydrates, additives and other inflammatory ingredients that should be avoided.
Ok, so we’ve talked a lot about sodium, but what about the other electrolytes? We discussed potassium and calcium in Part 1 , so we’ll focus on the other electrolyte that the majority of the population tends to be deficient in, and that’s magnesium.
What happens when you’re deficient in magnesium? A lot, so we’ll take a look at just a few.
- Muscle cramps- magnesium is what tells the muscle to “let go”
- Eye twitches-probably due to a deficiency in both B vitamins and magnesium(6)
- Restless legs-If magnesium is low, calcium isn’t blocked and nerves become overactive and trigger muscle contractions
- Anxiety-Magnesium normally keeps adrenal stress hormones under control(7).
- High Blood Pressure- (lots of studies on higher magnesium and/or potassium intake and lowered blood pressure)
- Hormonal Imbalances-Magnesium is required for adequate production of hormones, including progesterone, estrogen, and testosterone
- Poor Bone Health- you need Vitamin K, magnesium, vitamin D and calcium working together to support bone health
Other issues magnesium deficiency probably plays a large role in:
- Raynaud’s (a common issue for many female runners) – a deficiency of this mineral can result in spasms of the blood vessels(8)
- Angina- Studies have used injected magnesium to stop such attacks effectively(8)
- Cardiac Arrhythmia-a double blind trial showed that people taking 3.2 grams of magnesium daily had between 23% and 52% fewer occurrences of specific types of arrhythmia compared to those taking placebo(8)
- Fatigue- we know magnesium is needed for at least 300 (new research shows up to 800) biological functions in the body. The most important factor in energy production is ATP, which must be bound to a magnesium ion in order to be biologically active(9).
What causes magnesium deficiency? There’s a long list of things that can contribute to magnesium deficiency, so take a look at a few and see if any of these things apply to you:
- Lack of dark leafy greens and nutrient dense foods in the diet
- A diet high in processed foods as high sugar intakes increase excretion of magnesium
- Calcium supplementation- calcium is a competing nutrient. An overabundance of calcium increases the body’s need for magnesium and calcium cannot be effectively utilized or absorbed without adequate magnesium. It is commonly recommended to take calcium and magnesium supplements at a 2:1 ratio, but some health professionals believe even that ratio is not adequate(10).
- Supplementing with a magnesium supplement that is inferior in bio-availability
- Soft water
- Absorption issues in the gut such as Celiac disease.
- Kidney issues
- Soda. Phosphates found in carbonated beverages such as dark-colored sodas bind magnesium, rendering it unusable by the body.
- Certain medication (like birth control pills) and diuretics increase magnesium excretion
- Alcohol consumption
In order to improve magnesium intake, it’s always best to start with real food, but for most people, it’s probably not enough. When you think of foods high in magnesium think, for the most part, of high fiber foods. These include; green vegetables (kale, spinach, collard greens, turnip greens), nuts (almonds, cashews), seeds (pumpkin, chia), legumes (lentils, chickpeas), kelp, dark chocolate (with low sugar content), avocados, salmon and mackerel. Most people also do well to supplement with some form of magnesium, in which case it is best to find the form that works well for you. The less of a laxative effect it has, then the more of it that is getting absorbed into your system. For more information about sodium check out the book The Salt Fix by Dr. James DiNicolantonio and for more info on magnesium, check out the book The Magnesium Miracle by Dr. Carolyn Dean.