Salt Replacement During Training – How It Impacts Performance (#34)
The article explores the impact of fluid and mineral loss on the body during training and why salt replacement can be crucial for performance and health. It particularly questions whether drinking water alone is sufficient or if electrolytes are necessary during longer or intense sessions. By explaining how sweating affects the body's balance and the risks of one-sided fluid intake, the text concludes that while regular water is suitable for shorter activities, electrolyte supplements can be advantageous during prolonged efforts. The article also incorporates practical guidelines and personal experiences.
Salt & Mineral Loss During Training
Sweat is fascinating. All athletes sweat to varying degrees during their workouts. In extreme cases, you can lose as much as 4–5 liters of sweat during a longer competition in warmer climates. It's not just water that's lost – sweat also contains electrolytes. I won't list every single one, but the main macro elements (minerals we have in relatively large amounts in the body) are sodium, potassium, calcium, and magnesium. These are involved in a range of body functions and need to be maintained within a fairly narrow range for everything to operate optimally.
Exactly how much you sweat – and thus how many minerals you lose – is influenced by several factors. Training intensity and duration are two main factors, but genetics, body weight, diet, and how well-acclimatized you are to heat also play a major role. Therefore, it's difficult to provide universal advice on intake, but there are useful guidelines to start with.
Sweat – Our Wonderful Coolant
Sweat acts as the body's cooling agent. It's expelled through sweat glands and settles on the skin where evaporation cools us down. The majority of sweat is water, so both the fluid and the minerals you lose need to be replenished to prevent performance from being too affected.
Be cautious about only drinking water during longer sessions or competitions in the heat. The water you consume restores fluid balance but adds no minerals—thus diluting the minerals in your blood plasma. In extreme cases, this can lead to hyponatremia, a condition that, unfortunately, has sometimes led to fatalities.
You can lose as much as 5 grams of sodium (equivalent to 10 grams of table salt) during a single high-intensity 2-hour session, which can impair performance. A certain amount of sodium can be reabsorbed to some extent in the sweat glands, but the amount retrieved is negligible in most contexts. Below are average values for mineral content per liter of sweat. One liter of sweat can be lost quickly during high-intensity exertion or longer sessions—therefore, these amounts may be sensible to replace during the activity, at least if the training or competition continues for a while longer.
- Sodium: 890 mg/l sweat
- Potassium: 200 mg/l sweat
- Calcium: 18 mg/l sweat
- Magnesium: 1.5 mg/l sweat
Under normal circumstances, the body adjusts electrolyte levels by storing or excreting substances to maintain homeostasis. If you salt your food adequately and consume plenty of sodium, your sweat can also become more sodium-rich. During exercise, however, it's not certain that this balance is fully maintained. The body prioritizes cooling down, and this can lead to a temporary reduction in mineral levels—which in turn affects performance.
As you become better trained, you also become more efficient at cooling yourself, including sweating more and faster. This means that the need for electrolytes becomes more important as your performance level increases.
If you eat a varied diet, you usually get enough sodium and potassium. We Swedes, in fact, consume more sodium through a regular diet than recommended. Calcium and magnesium, however, can be harder to get in sufficient amounts, and balance issues can arise if you're an active athlete who sweats a lot. A supplement can then be valuable—either as a sports drink with energy and electrolytes or as water plus electrolytes if you don't have a sports drink on hand.
If you're familiar with your American lbs and oz, you can use Runners World’s sweat calculator (http://runnersconnect.net/training/tools/sweat-loss-calculator/) to estimate your sweat loss.
Overview
Numerous studies have examined the electrolyte balance in athletes, and there isn't a strong consensus on whether electrolyte supplements are needed during long-term training. What research agrees on is that there are no drawbacks to salt replacement, and there are no reported cases where people have felt unwell or encountered issues from salt replacement during training. If anything, it's positive, especially during longer workouts where the sweat really flows.
To summarize, regular tap water is sufficient as the main fluid replacement during and after physical activity lasting up to an hour here in Sweden. However, additional electrolyte supplements and/or sports drinks can be beneficial during longer performances to maintain electrolyte balance in the body. These minerals have many roles; for example, sodium can be beneficial to add a little extra to minimize fluid loss in urine during events like a marathon.
Personally, I've noticed that I feel much less thirsty during races when I drink water with electrolytes compared to just water, even during runs up to 60 minutes. No research to back it up, but I also want to share my personal experience.
Feel free to read our article on salt tablets where we compare different manufacturers and their contents.