Sweat TAlk (not Sweet Talk)

Sweating is one of the main ways we cool ourselves. Sweat containing mainly water and sodium moves to the surface of our skin via sweat glands. On our skin, the water in our sweat vaporizes when exposed to heat, leaving the salt behind. Ideally, we can use heat from our body to vaporize this water, which helps us cool.  I say ideally because in conditions when is too hot and humid, the air can vaporize the water before the body can, or the humidity can inhibit vaporizing because the air is already too wet. 

Unfortunately, there is neither an unlimited amount of water nor sodium in our body, and we need water for countless body functions, including some particular to athletics:

1)     Water establishes our blood volume. Therefore, our blood volume will fall if our body water is low. Because blood is responsible for carrying oxygen, our ability to supply oxygen to our working muscles will deteriorate, and we’ll slow down.

2)     Blood transports nutrients, including energy from food, vitamins, and minerals, to areas it needs. However, with low blood volume, our ability to transport nutrients to our working muscles will also decrease. More slowing; ugh!

3)     We need water to cool our bodies. Our bodies operate best in a concise temperature range. We will slow even more if we feel overheated from heat stress. If the body temps rise too high, we may become dizzy, nauseous, weak, confused, and possibly unconscious, AKA Heat Stroke.

Additionally, athletes need sodium for water absorption, retention, fluid balance, and muscle contraction.

1)     Water follows sodium. So, if sodium is low in our bodies, we won’t effectively absorb the fluid into our blood or around our cells. Instead, the liquid will bloat our gut.

2)     Sodium is essential in nerve transmission and muscle contractions. Therefore, when sodium balance is off, our muscles may contract involuntarily.

3)     Sodium keeps the fluid balance between the inside and the outside of our cells. Suppose we have too little sodium and too much fluid. In that case, too much water will go from outside to inside the cells where there is a higher sodium concentration. This condition, called hyponatremia, can cause grogginess, nausea, loss of balance, seizures, coma, and even death. This condition is called hyponatremia.

What should you do? The most straightforward answer is to drink fluids with electrolytes when exercising intensely or in hot environments for extended periods. However, understanding your sweat rate and sodium concentration will help you best meet your fluid and sodium needs. 

Measuring sweat rate is reasonably straightforward. Just subtract your post-workout weight from your pre-workout weight and add the weight of any drink or food consumed during the exercise. Then, calculate sweat loss per hour by dividing fluid weight lost by the workout time. You will want to perform this test for workout intensities and climates to understand your sweating tendencies more completely. From here, you can develop a hydration plan matching your sweat loss. If you lose over 3% of your body weight during a workout, you are not drinking enough, hindering your performance. 

A sweat analysis test can evaluate the sodium lost in your sweat. A low-sodium sweater may sweat 500 milligrams per hour or less, while a high-sodium sweater may lose 2000 milligrams of sweat per hour or more. Many sweat test analyzer tools are available, and you can purchase a one-time sweat analysis patch for around $15. If you do not have access to sweat analysis tools or services, you can do reasonably well by asking yourself if you are a low-, medium-, or high-sodium sweater. Do you have lots of salty deposits on your shirts, shorts, or skin after a workout, or not so much?

A low-sodium sweater consuming too much sodium may experience fluid retention, blood pressure increases, kidney stress, and a higher risk of kidney stones. More commonly, a high sodium sweater fails to take in enough electrolytes. In this case, the athlete is at risk of dehydration, muscle cramps, hyponatremia, and overheating.

The quick take home: know your sweat rate in all conditions, consider your sweat sodium concentration, and plan accordingly!