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As
the triathlon season enters full bloom in the heat of the summer, many athletes will suffer the performance detriments associated with dehydration which makes determination of fluid and electrolyte needs an important part of your
triathlon training program. In this article, I explore water’s role in human
performance and also explain how you can maintain peak performance as the
thermometer rises.
Water
is the medium for metabolic activity.
In order to properly metabolize the calories ingested during activity, the
athlete needs to be hydrated. Even
a slight level of dehydration, let’s say 1% (1.5 lbs for a 150 pound athlete),
can contribute to a 5% decline in metabolic efficiency.
What does this mean for the athlete?
Well, for one, the calories being ingested, especially solid calories, will be
left in the stomach rather than being distributed to the working muscles
leading to premature muscle fatigue.
Any fluids ingested will collect in the belly until a proper concentration is
achieved for optimal digestion leading to a shortage of fluid being directed to
working muscles and consequent muscle cramping.
When completing such jarring activities as running, all the food stuff
and fluids left in the belly, will be jiggling around leading to uncomfortable
side stitches, nausea, vomiting, and diarrhea.
Water
is a lubricant for our muscles and joints.
Noticeable muscle aches/pains/cramps can occur at the slightest bit of
dehydration and become debilitating as dehydration becomes more severe.
An athlete may also complain of headaches.
Water
helps cool the body.
Water can be compared to the coolant put in our cars.
When the coolant runs low, our cars overheat.
During exercise, blood flow to the skin increases as means to evaporate
the internal heat generated, aka “sweating”.
An athlete may have a flushed or blotchy appearance.
As dehydration becomes more severe, this process becomes compromised
causing core body temperature to elevate.
The athlete may get the “chills” or “goosebumps” when the heat being generated
is not efficiently being released from the body.
If left untreated, dehydration can lead to heat exhaustion or heat
stroke and potentially death.
Overall,
for every percent drop in hydration, expect a 3-5% decline in performance.
This is huge when you think about it…it would be like adding an
additional 1-2 minutes onto a 40 minute 10k runner.
In order to protect against these performance declines, I offer the
following hydration tips:
Don’t
wait until you’re 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 can reduce
maximal performance capability by up to 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
Fluids
will be absorbed more efficiently if taken in incremental fashions during the
day. Athletes should aim at
consuming ½-1 cup of fluid per waking, non-exercising hour during the day.
Note that these fluids should be non-caffeinated, as caffeine tends to
increase gastric emptying of fluids.
Top
off your fluid tank before you start training.
The American College of Sports Medicine (ACSM) recommends that athletes
fortify themselves with 16 ounces of non-carbonated and non-caffeinated fluids
for every 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, protect against hyponatremia, and also prevent muscle
cramps.
Adapt
to the heat.
Heat acclimatization is a process by which the body makes adjustments to
promote better cooling in hot environments. Sweat becomes more dilute. The
threshold at which sweating begins is lowered and the sweat rate is increased.
These, and other, changes take time to fully complete -- about 10 days of
exercise in the heat -- and will only work if you are well hydrated. Make sure
that you are properly adapted by training in conditions that you will
experience during the race.
Cut
your warm-up in half when racing in heat.
Avoid overheating prior to races in hot environments by staying cool
prior to your race. Many endurance
athletes who competed in the 2004 Summer Olympics in Athens cut their warm-ups
in half and stayed in an air conditioned building or wore a cool vest as means
to keep their core body temperature down prior to starting their hot races.
Be
weary of medications that interfere with cooling.
Certain drugs may cause dehydration or interfere with sweating.
Antihistamines and some blood pressure medications decrease sweating. Caffeine
and alcohol are diuretics and thus cause your body to lose water. You should
avoid their use for several days prior to the race. For those under a
physician's care it is best to check with your doctor about medication -- and
about your ability to race in the heat.
Know
your sweat rate as means to keep up with fluid needs during training.
Determination
of sweat rate is actually quite easy but it entails that you keep a log,
monitoring the following items:
Pre-Workout
Naked Weight
Post-Workout
Naked Weight
Total
Duration of Workout
Workout
Intensity
Weather
Conditions
Volume
of Fluid Ingested during Workout
Each
pound lost during a workout is equivalent to 16 additional fluid ounces (~1
water bottle) the athlete should have added to their fluid regimen.
To determine hourly fluid needs, subtract post workout weight from
pre-workout weight and multiply by 16.
This gives you an idea how many additional fluids they needed to consume during
the duration of the workout. Add
this number to volume of fluid ingested during the workout to determine total
fluid needs. Divide total fluid
needs by total duration of workout to determine the athletes hourly fluid
replacement needs. Note that as
the heat index rises and/or the intensity of the workout increases, sweat rate
will go up. For reference, the average athlete will lose approximately 1 liter
of fluid per hour (~2 water bottles), which is also is the approximate max we
can absorb per hour. At the
extreme, an athlete lost 30 lbs of water during a 2-day, 17 hour, 55-mile run
across Death Valley, which represented 3.5 to 4 gallons of fluid to cover his
fluid loss and replenishment requirements.
Don’t
neglect electrolytes in races lasting longer than an 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.
So remember: For the long
haul, use a sports drink containing electrolytes.
Rehydrate
upon completion of your race.
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.
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