Tips for carbohydrate loading
An informative article that sheds light on a subject I frequently get asked about - carbohydrate loading.
How to Carbo-Load for a Marathon
By GRETCHEN REYNOLDS
New York Times - Phys Ed
October 31, 2012
> Original Article
appears that despite the depredations of the big storm, the New York
City Marathon is likely to take place as scheduled on Sunday. While the
47,000 runners entered have too little time to remedy any major lapses
in training, there is one element that can still be tweaked, two new
studies show: what to eat in the days before the race.
ideal composition of a pre-marathon diet has been somewhat in dispute
recently. For years, marathoners were told that they should swallow as
many carbohydrates as possible in the week leading up to the race in
order to "load" their muscles with stored carbohydrates, or glycogen,
the readiest energy source for working muscles.
But such prolonged
carbo-loading often leaves runners bloated and heavy; when muscles pack
in glycogen, they also add water, and therefore weight, which must be
hefted throughout the 26.2 miles of the marathon. Women, in particular,
have been found in some studies to benefit little, if at all, from
prolonged carbo-loading before marathons.
However, a study
published last month in The International Journal of Sport Nutrition and
Exercise Metabolism found that carbo-loading can be effective for both
men and women - but is best if it's truncated, encompassing only a day
or so of dietary manipulation.
For the study, researchers at the
University of Minnesota turned to a ready-made pool of volunteers,
consisting of students enrolled in Physical Education 1262: Marathon
Training, who were aiming to finish the local Eau Claire Marathon for
Forty-six students joined the study, 36 of them women and all but two of them first-time marathon runners.
Several weeks before the event, the runners completed a two-mile time trial, to determine their endurance and running ability.
beginning three days before the race and continuing through breakfast
on race morning, they kept detailed food diaries. They also noted, to
the extent possible, what they ate and drank during the race.
All of the students finished the race, with an average time of 4 hours 43 minutes (and, one would hope, an A grade in P.E.).
statistical analysis showed, those runners, both men and women, who'd
eaten the most carbohydrates on the day before the race finished faster
than those who'd eaten fewer carbohydrates that day.
neatly replicate those of a larger study published last year of 257
male and female runners who completed the 2009 London Marathon. Those
runners also kept detailed food and training diaries, which researchers
compared with their finishing times. In this case, the scientists also
tracked each runner's pace at five-kilometer increments throughout the
They found that, as in the Minnesota study, runners who'd
loaded up on carbohydrates the day before the race ran faster than those
who had eaten fewer carbohydrates. The difference was especially
striking beginning at about the 18-mile mark, just when many runners
famously "hit the wall" and feel their energy flag. The carbo-loaded
runners jauntily maintained their pace. The others did not.
both studies, carbohydrates eaten at breakfast on race day, during the
race itself or on days earlier in the week were relatively unimportant.
It was primarily what people ate on the day before the race that
And yet, few of the runners in either study actually
consumed enough carbohydrates to benefit, even if they thought that they
were doing so. In both studies, the minimum effective "dose" of
carbohydrates was at least six or seven grams for every kilogram of a
person's body weight, or about a quarter-ounce of carbohydrates for
every 2.2 pounds of body weight. By that formula, a 220-pound runner
would need to consume at least 25 ounces, or more than 700 grams, of
carbohydrates on the day before a marathon to finish faster.
the Minnesota study, fewer than a quarter of the marathoners consumed
that many of carbohydrates on the day before the race. In the London
study, barely 12 percent did.
What those numbers suggest is that
many more marathon runners could benefit from a brief bout of
carbo-loading than currently do. And the process itself is relatively
simple, says Patrick Wilson, a graduate student at the University of
Minnesota who led the study of novice runners. You don't need to
increase your food volume or calories the day before a race; just
replace some fats or proteins with carbohydrates.
"I often tell
people to choose relatively concentrated sources of carbs, like juices,
pasta, rice and sweets," Mr. Wilson says. "That way, the volume of food
needed isn't so enormous." In addition, he says, "lower-fiber foods may
be good, since that could reduce the potential for stomach distress
during the race." (According to a rather intrusive study this year,
extremely high intake of carbohydrates was associated with faster times
during endurance races but also with "nausea and flatulence.")
completely upend your normal diet, though. "Stick to foods that are
familiar," Mr. Wilson says. "It's always a bad idea to experiment right
before a race."
And don't expect that diet alone will lift you
from the back of the pack. In the British study, every increase of 1
gram per kilogram of body weight in the carbohydrates that runners
consumed on the day before the race increased their speed by about 0.1
miles per hour.
Far more important in the overall determination of
people's finishing times was their training and their fundamental
fitness. In the Minnesota study, the runners who were fastest during the
time trial were fastest in the marathon, too.
You can't alter
your training or talent at this point. You can, though, have a chocolate
chip cookie on Saturday and call it race preparedness.