The optimum core body temperature ranges from 96.8ᵒF – 102.2ᵒF, and this temperature rises to become up to 20 times greater during exercise, particularly during warmer weather. All strenuous exercise will elevate body temperature, which causes us to sweat. But as we become accustomed to a particular exercise, our bodies have to work less intensively to regulate under exercise conditions.
This is where CrossFit is different to other forms of exercise: it is a high-intensity approach to exercise with variety at its core. This means we are always working hard, and our bodies don’t get used to one particular exercise. For this reason, it’s likely that a CrossFit workout will make us sweat more than a regular workout, causing us to lose more water and essential minerals. Proper hydration during CrossFit training is, therefore, vital.
How CrossFit Is Different
CrossFit combines different forms of exercise, borrowing movements and techniques from a variety of sports and training programs. A CrossFit workout might involve weights, plyometric training, calisthenics and gymnastics, and will vary from workout to workout. It is neither solely about strong, explosive movements nor endurance, tapping into both aerobic and anaerobic energy systems, and requiring participants to complete as many reps of an exercise as possible in a given amount of time.
CrossFit workouts are always intense, whether exercises are performed for maximum reps or for time. This targets your cardiac capacity, anabolic threshold and muscle mass all at once to make your workout as effective as possible in a short amount of time. This is the reason training gear is developed specifically for CrossFit: it’s a wear and tear sport requiring clothing to provide flexibility and support to keep you safe during training. It’s also the reason that hydration is particularly important.
How The Body Regulates Temperature During CrossFit Training
As the body’s core temperature rises during a workout session, heat is dissipated through sweat. During an intense CrossFit session, the blood has to be distributed between the organs and the muscles, and also the skin for sweating. As the session intensifies, body temperature rises and sweat rates increase in response, reducing our blood volume and causing the heart to work harder in order to deliver oxygen to the muscles.
As we sweat, we lose both fluid and electrolytes – primarily sodium and chloride, but also small quantities of calcium, potassium and magnesium. A 2010 study on professional footballers published in the Journal of Athletic Training found that subjects lost between 642mg and 6.7g of sodium per hour of play, and this varied between the body mass of players and position of play. The amount of sodium lost during a CrossFit training session will, therefore, vary between individuals, but due to the work required of the heart, it’s certain that significant quantities of sodium will be lost.
What Does This Mean For CrossFit Training?
Sodium ensures that fluid volumes in the body are maintained, and this affects blood pressure and volume. Keeping sodium at a healthy level during CrossFit training can be achieved by ensuring that intake and excretion are balanced. It is when they are not that health complications, such as hyponatremia (low sodium content in the blood) can occur, and performance is negatively affected. Avoiding an imbalance simply means making sure that fluid intake does not exceed sweat loss, and consuming sodium to replace what is lost in sweat. If this is done, individuals participating in CrossFit will get the most out of their training, as they will be able to perform at their peak throughout the session.
Pre-hydration Before The Session
The body should be fully hydrated before a CrossFit session. Rehydration after exercise can take between eight and 12 hours through regular food and drink intake, so drinking an electrolyte drink four hours before training can help this process along. This will allow urine output to occur at the usual frequency before exercise begins. Your urine should be a pale straw color – this signifies that you are well hydrated before you begin training.
Hydration During Training
Professional athletes are encouraged to develop personalized hydration plans specific to their sweat rates. For CrossFit training, a simple way to check the volume of sweat lost during a session is to weigh yourself both before and after a one hour CrossFit session, monitoring fluid intake along the way. After the second weigh-in, calculating the difference in body weight will give you an idea of fluid loss. For example, if your weight before exercise was 75Kg, and afterwards it was 74.5KG, and you had ingested 500ml of fluid during training, your sweat rate would be 1L per hour (75Kg – 74.5Kg = 500g + 500ml = 1). This would mean you should drink approximately 1L per hour during training. To maintain electrolyte levels, this could be split between 500ml of water and a 500ml sports drink.
It is also important to pay attention to thirst during training. Consuming electrolyte drinks as well as water is a more beneficial way of rehydrating, and will aid the absorption of water and promote thirst.
Rehydration After Training
Rehydration after CrossFit training is as important to recovery as protein intake. Generally, fluid balance is regulated by the feeling of thirst and the output of urine, but an intense CrossFit session places abnormal stress on the body, which can affect thirst. Depending on the severity of fluid loss, it can take several hours to rehydrate, which can become a problem if another training session is planned. 1.5L of fluid should be consumed for each 1KG of body weight lost during training, and this should be done over the first two to four hours after the session. Drinks containing electrolytes will help the body retain fluid, and consuming salty foods like nuts alongside water will have the same effect.
Why Water Isn’t Enough
A 2015 study published in the American Journal of Clinical Nutrition compared the hydration effects of a variety of drinks from plain water to milk to tea. After analyzing urine samples from subjects, researchers concluded that orange juice, milk and tea were more hydrating than plain water. Interestingly, sports drinks were not found to be more hydrating. The study authors wrote that a drink’s nutrient content and the presence of diuretic agents affect the amount of water the body is able to retain. Consuming minerals, fats and amino acids alongside water enables the body to retain more fluid, maximizing hydration.
This is particularly important after an intense training session, when sweat loss has been significant. Excessive water consumption, in rare cases, can be harmful. Athletes drinking only water can lose too much sodium in their urine, disrupting the balance in the body and leading to hyponatremia. For those training intensively, drinks containing other nutrients and sodium are safer.
Natural Alternatives To Energy Drinks
For those who would rather not consume commercial energy drinks, as long as adequate fluid is consumed, there are foods you can eat after a CrossFit session to replenish your electrolytes. Milk and yogurt are valuable sources of calcium, and have the added bonus of being rich sources of protein to further aid the recovery process. A small-scale study published in the British Journal of Nutrition found that a measured intake of milk post-exercise restores the fluid balance in the body better than a carbohydrate-electrolyte solution such as a sports drink.
Bananas can also help replenish electrolytes lost through sweat. Each banana contains approximately 422mg of potassium. David Nieman, professor of public health at Appalachian State University, found that eating a banana is more beneficial than consuming a sports drink after exercise. He says that eating fruit alongside water will aid the body’s ability to absorb the water and rehydrate effectively.
Coconut water, meanwhile, contains potassium, calcium and magnesium, as well as sodium, and its natural sugar content will help to replenish glycogen stores after training. It is also rich in Vitamin C and iron, which help replenish energy levels.
Alternatively, you can make your own electrolyte drink. Add ⅛ – ¼ tsp of Himalayan salt and 1tsp of calcium magnesium powder to 1L of coconut water and ¼ cup of natural juice, and shake well to combine. The mixture will keep for up to four days in the refrigerator, and can be used both during and after training.
Hydration is important alongside any training schedule, but it is important to be aware of sweat loss in order to rehydrate adequately. CrossFit training is effective because of the intensity and variety of the workouts, which cause the heart to work harder. A side effect of this is increased sweat production. For this reason, when you begin CrossFit training, it’s important to be mindful of how much sweat you’re losing in order to rehydrate fully and perform at your best every time. Complete rehydration for intensive training will require more than just water though: ensure that your electrolytes are topped up after each session to be sure that you absorb all the fluid you ingest and replenish essential minerals lost through sweat.
Jacob Hatch is the author and founder of Hydration Anywhere. He has been actively writing about drinking water since 2013. These days Jacob spends most of his time investigating water related news, studying environmental issues, reading health studies, and reviewing products like water bottles and water filters.