Dehydration: H2 “Oh no”s

Don’t fear- the purpose of this post is not to tell you to drink at least eight glasses of water a day.  I have a hunch that that idea has been drilled into your heads by this point.  So rather than beat a dead horse, I’d like to discuss just HOW dehydration could be detrimental to your athletic performance.

Studies have found that dehydration (sweat losses greater than 2% of your body weight) can lead to the following:

- Increased perceived exertion

What it means:  Everything will feel harder than usual (i.e. you’ll likely have a desire to walk when you turn the corner on that 400m run).  This is especially true if you are dehydrated due to an evening of excessive alcohol intake.  Not that any of you drink…

- Increased cardiovascular strain

What it means:  Your capacity to perform aerobic activities will be lowered, meaning you may feel the need to increase rest breaks.

- Increased glycogen utilization

What it means:  You’ll burn up your energy stores faster than usual, bringing you to exhaustion more rapidly.

- Degradation of cognitive performance

What it means: Very technical movements involving concentration will become more challenging and it may become difficult to maintain proper form on your lifts. Also, if you ever find yourself in a competition where there is a logic puzzle involved, consider yourself toast.

The above physiologic effects have only been found to have a negative impact on aerobic performance, not muscular strength or anaerobic performance (anaerobic means “without oxygen”; activities include heavy weight lifting, sprinting, or any other rapid bout of difficult exercise), but don’t think that means hydration is only important for long runs.  Your body can only perform anaerobic activities for a short period of time before transitioning to aerobic, or oxygen-utilizing, exercise.

For those of you who do two workouts in a day, you are at an even greater risk for dehydration.  If you are in a fluid deficit from the first workout, it will likely be carried over into the second, and your performance will suffer.  Additionally, heavy sweaters (I’m talking to those of you that can soak your entire shirt in 30 minutes) should be particularly mindful of their fluid intake.  If you are a heavy sweater or a two-a-day-er, I recommend occasionally weighing yourself post-workout to monitor fluid losses.  Anything greater than 2% of your body weight (i.e. 3 lbs. for a 150 lb. athlete) indicates severe dehydration.

Aim for at least 64 ounces of cold, clear deliciousness a day. Mmm…who’s thirsty?