What Dehydration does to Your Body

Practically everyone knows that it is important to stay hydrated while exercising in heat. But, did you know that dehydration is just as likely during physical activity in normal temperatures, cold weather, and even indoors?

The human body needs an adequate level of hydration to regulate internal temperature effectively and to ensure the cardiovascular system functions properly. Too little – or too much – fluid can upset the blood’s concentration of ions and the body’s overall pH. Ions such as potassium, calcium, and sodium dictate the direction of water flow across cell membranes inside the body. These ions are involved in many physiologic functions, but most important in physical activity, they are necessary for nerve conduction (sending a nerve signal from one place to another) and muscle contraction. If the body is not well hydrated or does not have enough ions, fatigue, and a host of other negative consequences, will set in.

Losing weight during an exercise session that amounts to as little as less than 2% of regular body weight degrades performance, reduces the capacity for exercise (both in terms of exertion and length), hinders the body’s ability to regulate its temperature, and impairs cardiovascular functioning. Less than 2%. Put that in context: If you weigh 120 pounds at the start of your workout, losing just 2 pounds during your workout classifies you as being dehydrated and negatively influences your performance and your body’s functioning.

Other effects of dehydration include:

• An inability to generate enough energy
• Feeling weak
• Reduced muscular strength and endurance
• Decreased blood and plasma volume (can be a problem for those with low blood pressure, positional vertigo or dizziness, or anemia)
• Decreased kidney function
• Reduced glycogen stores (needed to produce energy in aerobic metabolism)
• A loss of electrolytes (the ions mentioned above)

Now, it’s common sense that if someone is exercising, they are going to experience some dehydration. The body will lose water through sweating and breathing, and it is very difficult to maintain a neutral level of hydration throughout physical activity. However, most people replace only half of the water that they lose during activity. This is why it is especially important to start an exercise session or rehearsal fully hydrated. The best way to do this is to consume fluids throughout the day – before, during, and after your rehearsals, performances, and workouts.