Coach’s Note By Lance Watson: Wasted Performances Due to Dehydration?

As we are now entering racing season, temperatures are starting to rise. Being well hydrated in a race is a key to maximizing race performance. Being in tune with daily hydration levels impacts training performances, and ultimately racing fitness.

A 2010 study published in the Journal of Athletic Training titled “Influence of Hydration on Physiological Function and Performance During Trail Running in the Heat” (Douglas J. Casa et al.) put well-trained runners through four 12K runs in moderate heat (average temperature was 80 degrees F/26.5 degrees C): (1) a hydrated race trial; (2) a dehydrated race trial; (3) a hydrated submaximal trial; and (4) a dehydrated submaximal trial.

In sub-maximal running tests, when dehydration increased, post-run body core temperature and heart rate were approximately 0.5 degrees C and 15 beats per minute higher, respectively, even though intensity was moderate, finishing times were the same, environmental conditions were not extreme, and differences in hydration status were just 2.5 percent.

In maximal running tests, finishing body core temperature was lower in the hydrated runners, even though they were running at a faster pace. This finding is surprising because exercise intensity plays such an important role in the rate of body core temperature rise.

Many triathletes underestimate the importance of proper hydration while training and racing. After only 1–2 percent of a person’s body weight is lost through sweating, his performance will be affected negatively. Dehydration is a major cause of fatigue, poor performance, decreased coordination and muscle cramping. All active people can increase performance and delay fatigue or muscle pain by staying properly hydrated. How can you keep track of how well hydrated you are or figure out if you are dehydrated? We all know what thirst feels like, and in exercise, if you feel like you are dehydrated, it’s already too late.

Most people are familiar with the standard hydration plan: Drink eight glasses of water a day. While this advice is useful, athletes need a plan that is tailored to their training needs.

The most basic way to start to figure out hydration begins in the morning. When you first wake up and use the  bathroom, take a peek at your urine. If it is clear or slightly yellow then you’ve done a good job; you kept yourself hydrated throughout the previous day. You took in as many fluids as your body eliminated through sweat and urine, and that kept you hydrated. This means you can consume fluids at the same rate that you did the previous day, taking into consideration your duration and intensity of exercise. On the other hand, if your urine is bright yellow then you are likely dehydrated. Think back to what you did the previous day. Did you have a long workout in the heat, and how much and how frequently did you drink? If your urine is very yellow in the morning then you just didn’t get enough fluids the day before and you must increase the amount and frequency that you drink.

Most people are unable to accurately calculate how much fluid loss their bodies are experiencing during their workouts, so to take the guesswork out of hydration, use a scale. The scale will help you to figure out how much water your body loses during certain workouts.

Here is a sample for cycling. You can also do this with other endurance training activities.

1. Do a warm-up run to the point where perspiration is generated.
2. Urinate if necessary.
3. Weigh yourself naked on an accurate scale.
4. Bike for one hour at intensity similar to the targeted race.
5. Do not urinate or eat. Measure how much you drink.
6. Weigh yourself in the nude again on the same scale after the ride (clothing gets heavy when sweaty).

The difference in weight can be attributed to dehydration (sorry, but you haven’t lost fat!). Once you figure this out, you can plan ahead by increasing your fluids before, during and after a training session to initially top yourself off and then keep your fluid levels up throughout the workout and the rest of the day. For each pound of you have lost, you are in a fluid deficit of 24 ounces or 700 milliliters. This is how much you must add to your regime in order to replace this fluid.

RELATED – Water Wars: The Dehydration Debate

Tips on Maintaining Hydration:

• Consider “pre-hydrating” by drinking 16–20 ounces (500–600 mL) of water or fluids 2–3 hours before exercising, and then another 7–10 ounces (200–300 mL) of fluids 10–20 minutes before beginning an activity. Starting an activity with fluids in your stomach will allow your body to get used to digesting and absorbing fluids while the demands of your activity are present. The chances of getting a stomach cramp in the middle of a workout or race will be lessened if your stomach has been trained to deal with this fluid.
• Keep fluids on hand and accessible. Use a water belt to carry fluids with you or place them somewhere nearby so that you can “top off” while continuing through your workout. Many long-distance runners will drive to a couple of spots along their routes before they begin their runs to drop off water bottles.
• Use your watch for more than timing the duration of the session. Plan to drink at certain intervals (such as every 20 minutes during a two-hour run), whether you feel thirsty or not.
• Clothing can also lead to dehydration. If you train with too many layers of clothing during the cooler months of the year, your body will begin to sweat at an increasing rate whilst trying to cool itself down. Plan to do a warm-up loop and come back to a place where you can safely store you clothes. This will allow your muscles to stay warm until your body’s warmed up and then allows them to keep cool efficiently when you begin to work hard.
• Sunny days can be great for training, but keep in mind that your body will lose more fluid during the summer or in hot weather. It is important to take this into consideration and plan for it. Keep drinking after the session, and when in hot climates, sip all day long.
• Learn to drink on the bike. More than one subpar performance has been caused by neglecting to drink on the bike. Practice the skill of riding with one hand and pulling out your bottle and drinking while continuing to pedal.

Proper hydration is paramount to performance and recovery, so next time you head out for a workout, make it a goal to come back at the same weight that you left.

LifeSport head coach Lance Watson has coached a number of Ironman, Olympic and age-group champions over the past 25 years. He enjoys coaching athletes of all levels. Join Lance to tackle your first triathlon or perform at a higher level. 

RELATED: Staying Hydrated On Long Runs

More from Lance Watson.