This month officially marks the start of the summer season. I hope all of you have cool vacations planned that include lots of physical activities. As the temperatures rise through the summer, it becomes extremely important to monitor when, where and how much exercise you should be doing along with hydrating properly.

Did you know that water accounts for more than 60% of the human body’s volume? Water is so vital to life that we can survive only about three days without it depending upon climate conditions. The hotter and more humid the environment, the faster we become dehydrated. It takes as little as a two percent change in body weight to negatively affect exercise performance. For a 150lb person, that equates to only 3lbs!

There are many factors that affect your hydration status such as:

• Ambient Air Temperature (Outside)
• Humidity
• Individual Sweat Rates
• Body Temperature (Internal)
• Exercise Intensity & Duration
• Fitness Level
• Individual Body Fat Percentage
• Existing Health Conditions such as cystic fibrosis, diabetes, kidney failure, etc.

Dehydration can have several negative effects during exercise such as decreased muscle strength & endurance, coordination, mental acuity, and impaired thermoregulation. One of the most important functions of water within the body is to help regulate body heat. When the body is properly hydrated, exercise will feel easier and you will typically have a lower heart rate at the same intensity than you would if you were in a dehydrated state. This is due to optimal blood volume and cardiac output to deliver nutrients and oxygen to your working muscles.

There is no single “Gold Standard” for measuring hydration levels because too many factors play into how your body stores water. However, here are some general exercise and hydration guidelines to follow this summer:

• Try to workout during the coolest part of the day if outside (usually mornings)
• Weigh yourself before & after your workout to monitor sweat loss
• Drink about 10 ounces of fluid 1 hour before your workout
• Drink 8 ounces of fluid every 15 minutes during exercise
• Drink 20 ounces of fluid per pound of weight lost through sweat after exercise
• Always finish a workout with a cool-down by gradually decreasing intensity
• Use a cool, damp towel on the neck to help bring body temperature down
• It’s better to have a sports drink (Gatorade, Powerade, Propel) to replace electrolytes (mainly sodium) after a prolonged workout over 60 minutes

It’s easy to overdue it especially if you’re not accustomed to the environment (i.e. vacationer or traveling). There is a progression of heat-related illness (heat exhaustion and heat stroke) that can be fatal if action is not taken. Muscle cramping is usually the first sign of a heat-related illness. Here are the main differences between the two and what actions are required:

Heat Exhaustion                                    Action Required
Heavy sweating                                     Move to cooler location
Weakness                                               Lie down and loosen clothing
Cold, pale,clammy skin                       Apply cool, wet cloths to most of the body
Fast, weak pulse                                    Sip water
Nausea or vomiting                              If you have vomited and it continues, seek
Fainting                                                  medical attention immediately

Heat Stroke                                                Action Required
High body temperature (over 103 F)     Call 911!-This is a medical emergency!
Hot, red, dry or moist skin                       Move person to cooler environment
Rapid, strong pulse                                    Reduce person’s body temperature by any
Possible unconsciousness                         means possible (cold cloths or ice bath). Do not give fluids.

Source: http://www.cdc.gov/extremeheat/warning.html

It’s essential to know the differences between the two. I don’t want to scare you away from exercising this summer, but after reading this article, hopefully you’ve gained an appreciation for the importance of hydration while exercising in the heat.

Written by: Ryan Unverzagt