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Imagine the beautiful desert sun beating down your neck as you begin your
training. In a rush, you have forgotten your camelback full of sports drink. As
you continue, you start to notice a muscle cramp developing in your calf which
soon turns into an annoying muscle twitch. At last, a water fountain arrives.
You take a few sips and continue on. Unfortunately, the unpleasant cramp
returns and suddenly, your breathing starts to act up almost as if you are
having an asthma attack. Even though that potent sun continues to beat down
your neck, you start to get the chills. A bout of dizziness follows, causing
you to stumble over a rock. As you try to get up, your heart starts to race and
you lose consciousness. These symptoms are associated with a fluid and
electrolyte imbalance, which can be extremely dangerous with respect to health
and can have a profound negative impact on endurance performance. Read on to
discover five tips to help keep cool in the heat.
#5 DON’T WAIT UNTIL YOUR THIRSTY TO START DRINKING!!!
Perhaps the biggest mistake endurance athletes make is waiting until they are
thirsty to start drinking. Upon the onset of thirst, an athlete is already 3%
dehydrated which reduces maximal performance capability by 15%. This adds up to be a large chunk of time when looking at such endurance events as marathons, long-course triathlons, and adventure races. In fact, one study discovered a
6-7% reduction in 5k and 10k running speed in athletes who were 2% dehydrated.
This would be equivalent to adding 2 minutes 48 seconds to a 40 minute 10k.
Dehydration becomes life-threatening when 10-20% of body weight is lost.
To prevent dehydration, it is best to sip on fluids throughout the day until
urine flows clear to pale yellow. Daily fluid needs vary depending on the body
composition and total weight of the athlete. The following equation can be used
to estimate daily fluid needs in ounces:
Body weight (in pounds) / 2 = Daily Fluid Needs in Ounces
Note that these fluids should be non-caffeinated, as caffeine intakes greater
than 300 mg tend to increase gastric emptying of fluids.
#4 TAP OFF YOUR FLUID TANK BEFORE TRAINING.
The American College of Sports Medicine (ACSM) recommends that athletes fortify
themselves with at least 16 ounces of non-carbonated and non-caffeinated fluids
about an hour prior to exercise. For those who have trouble holding fluids, try
sipping on a sports drink containing sodium that last hour rather than drinking
all 16 ounces at once. The sodium in the sports drink will help increase
absorption of the water into the cells and also may help stave off muscle
cramps.
#3 STAY ON TOP OF YOUR FLUIDS DURING YOUR WORKOUT.
Maintaining fluid balance during exercise requires replacement of fluids that
are lost via sweat and urine by drinking such hydrating beverages as water and
sports drinks. The American College of Sports Medicine recommends drinking 5-12
ounces of fluid every 15-20 minutes of exercise. If the exercise bout is under
an hour, water is an appropriate fluid replacement beverage. Beyond an hour, a
sports drink containing a 7% concentration of carbohydrates will help enhance
performance.
In order to get a more exact estimate of your fluid needs, determination of
sweat rate is necessary. To determine sweat rate, weigh in both immediately
pre- and post-exercise on several different occasions. Every pound of body
weight lost during exercise is equivalent to approximately 16 ounces of fluid.
For example, if you consistently lose 1 pound of body weight on a 30-minute run
where you are not drinking anything, your hourly fluid needs are 32 ounces per
hour. Use the card below to jot down your hourly fluid needs in different
conditions (hot & humid versus cold & dry; intense intervals versus
long run).
Calculated Fluid Needs
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Date |
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Workout
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Pre-workout
Weight (lbs) |
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Post-workout
Weight (lbs) |
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Weather Conditions |
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Calculated Fluid Needs
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#2 DON’T NEGLECT ELECTROLYTES IN EXERCISE LASTING >1 HOUR.
In addition to fluid replacement, replacement of electrolytes becomes
instrumental in endurance bouts lasting longer than 1 hour, especially when
completed in hot and humid conditions. The principle electrolytes include
sodium (generally bound to chloride), potassium, magnesium, and calcium. These
electrolytes are involved in metabolic activities and are essential to the
normal function of all cells, including muscle function. An electrolyte
imbalance has reported symptoms similar to dehydration: nausea, vomiting,
muscle weakness, muscle cramping, muscle twitching, overall fatigue, labored
breathing, “pins and needles”, and confusion. The table below displays the
function of the principle electrolytes and goal dosing patterns during exercise
and performance daily intake (PDI) recommendations for athletes.
A potentially life-threatening condition can occur if an athlete fails to use
an electrolyte-replacement drink during exercise bouts lasting longer than an
hour. There have been several incidences of “water intoxication” in athletes,
which causes blood sodium levels to drop dangerously low, causing an
electrolyte imbalance and triggering seizures, coma, and even death. Initial
symptoms are similar to dehydration and include confusion, disorientation,
vomiting, and muscle weakness. So remember: For the long haul, use a sports
drink containing the electrolytes displayed in table 1.
Table 1. Electrolytes to replace during exercise
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Electrolyte |
Primary Roles
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Dose per 8-12 ounces of fluid |
Performance Daily Intake (PDI)
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| Sodium |
Muscle contraction
Nerve transmission
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150-250 mg
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1,500-4,500 mg
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| Chloride |
Peak muscle function |
45-75 mg
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| Potassium |
Muscle contraction
Nerve transmission
Glycogen formation
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50-80 mg
|
2,500-4,000 mg
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| Magnesium |
Muscle relaxation
ATP (energy) production
|
20-30 mg
|
400-800 mg
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| Calcium |
Bone health
Nerve transmission
Muscle contraction
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10-15 mg
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1,200-1,600 mg
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#1 REHYDRATE UPON COMPLETION OF TRAINING.
For every pound of body weight lost during exercise, consume 16-24 ounces of
fluid as means to rehydrate and enhance recovery from exercise. Sports drinks
are desirable for post-workout rehydration due to the sodium (which increases
fluid absorption) and carbohydrate (replenishes lost glycogen) content.
On a final note, it is important to be careful out there especially if you are
training alone. Increased heat and humidity makes optimal fluid and electrolyte
replacement challenging. If you start to experience any symptoms associated
with dehydration (nausea, vomiting, cramps, fatigue, and goose bumps), it is to
the benefit of your health and wellness to stop and aggressively replace your
fluids and electrolytes with a sports drink.
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