Feature
Optimal
Hydration
For decades the mantra drilled
into endurance athletes was to
“Drink ahead of thirst,” but as
our understanding of the body’s
hydration requirements during
strenuous or prolonged exercise
have evolved, new guidelines have
since emerged.
(Courtesy Living Fit Magazine)
T
he conventional advice suggested that athletes drink
three litres of water a day, and an extra 500ml for every 20
minutes of strenuous exercise. If you crunch the numbers,
that’s 1.5 litres of fluid every hour during exercise! So, if you run
a marathon or compete in a cycle race that lasts for four hours,
you’ll conceivably drinks six litres of fluid... a truly eye-watering
figure. Double the distance and time for an Ironman triathlon or an
ultra-marathon and athletes could conceivably consume between
8-12 litres during an event.
These guidelines exist for a number of reasons, from the
misinterpretation of scientific evidence by authors of popular
running books, to the aggressive marketing of sports drinks in the
US since the 1970s. These factors have fuelled a culture of over-
hydration, whereby most athletes tend to drink far too much while
training and racing, particularly in hot and humid conditions.
While drinking this volume of fluid may seem logical as a strategy
to stave off the performance-sapping effects of dehydration, it
can actually lead to a more serious condition. Over the last few
years a clearer picture has emerged of our real hydration needs
during exercise. This new model indicates that mild dehydration
– about a 2% to 6% decrease in body weight based on various
studies – does not impair exercise performance in the heat, and
that over-hydration is a far greater concern because it can lead to
a condition known as exercise-associated hyponatraemia.
Hyponatraemia is a serious condition where serum sodium
concentrations (the amount of sodium in your blood) drop to
critically low levels due to a shift in water balance. This condition
can lead to various symptoms that range from mild to life-
threatening. These include nausea and vomiting, a headache,
confusion, disorientation, drowsiness, slurred speech, fatigue
18
Dis-chem Half Marathon | 12 January 2020
Deadly Serious