Many thanks for all those who got in touch with comments for the
cycling re-fuelling article and sorry that I didn't quite get around
to replying to everyone.
But, as promised here (below) is a copy of what I intend to file, so
feel free to point out the inevitable glaring errors - I'm sure
there are some, what with me being a lowly journo and untalented
athlete, rather than knowledgable sports scientist!
Only catch is - got to file in 24 hours time so any comments before
then, please!
HAVE YOU GOT THE GUTS FOR IT??
Training Your Stomach for Optimal On-Bike Re-Fuelling
Everyone knows that to perform well you need to train your
muscles, your cardiovascular system and your mind. But few people
recognise that it can be just as important and just as possible
to train your stomach too. Taking on board the amount of
carbohydrate and fluid needed to maximise performance over a long,
high-intensity ride is not something you can just do. It must be
practised. It's also a highly individualised area, so although the
problems are common a sloshing stomach, nausea, taste fatigue etc
solutions may vary from rider to rider. Following these tips should
help you find your successful strategy.
Understand What's Going on Inside
For most, riding for longer than an hour requires fluid to
stave off dehydration and carbohydrate to top up energy (glycogen)
stores. Sports drinks are handy in this regard because they're
designed to accomplish both whereas water only provides fluid and
gels or energy bars only top up glycogen.
The problem is that at race pace it's hard to stomach the
amount of sports drink you need, which, according to a study by the
Gatorade Sports Science Institute and Montreal University, could be
as much as a litre per hour. Drinking that much often leads to a
sloshing stomach and nausea. To understand why, it's necessary to
look at what happens inside. The drink must exit the stomach into
the small intestine a process known as gastric emptying where it
can be absorbed into the bloodstream and carried to the muscles to
provide energy. However, studies show that gastric emptying is
reduced when you're working really hard.
"High intensity exercise drives blood volume into the
working muscles for evaporative cooling," said Dr. Bill Misner of
Hammer Nutrition. "This is a natural mechanism to protect the brain
from overheating, but it means blood volume to the gut is inhibited.
If drinks don't contain the same particle-content or osmolality as
bodily fluids then for them to be absorbed the gut needs to pull
fluids out of the system to dilute them or nutrients to do the
opposite. During such a time the drink `sloshes' around."
Do a Bit of Self Analysis
Armed with this knowledge the next step is to do a bit of
self-analysis. You need to decide on your priorities. Essentially
this boils down to: do you need to take on a lot of fluids? Or
carbs? Or both? With regards to fluids, weighing yourself before and
after a long ride is a good method. If you're a heavy sweater you'll
be considerably lighter afterwards due to fluid loss. In that case
hydration will be a priority for you and you need to drink enough to
ensure a bodyweight reduction of 2% at most. If you're a light
sweater, taking on masses of fluid may actually be a bad thing as
it'll simply provide extra ballast.
"For some, the time lost through a modest level of dehydration may
be less than the time taken to constantly reach for a bottle and top
up," said Dr. Susan Shirreffs, an exercise physiologist from
Loughborough. "It's a trade-off and the only way to find out what
works for you is to experiment."
In terms of carbs, you need to look at whether you have a tendency
to bonk at the end of rides. If so, you're probably not taking on
enough, so try supplementing your sports drink with gels or energy
bars.
Mix it Up
Of course, working out your ideal plan doesn't necessarily
make things easier. If you're a heavy sweater and require lots of
carbohydrate, you'll be putting an awful lot into your stomach,
which may feel uncomfortable at first. This is where training - and
tinkering - comes in.
Manufacturers have done their best to help. Most sports
drinks contain 5-7% carbohydrate and are "isotonic," meaning the
drink matches the osmolality of bodily fluids closely allowing for
easy absorption (and less sloshing.) But you may still want to
experiment. For example, a team at Birmingham University found a
mixed glucose/fructose drink left cyclists with less of a "full
stomach" than a pure glucose drink. Similarly, in an experiment at
Liverpool John Moores University, a 15% maltodextrin solution
significantly improved performance in trained cyclists compared to a
5% glucose drink without any increase in stomach issues.
Another reason to experiment is `taste fatigue'. Sports drinks are
quite sickly sweet and consuming the same drink all through a long
ride causes the taste to stick in the mouth, exacerbating feelings
of nausea and making riders reluctant to drink further.
"Simply taking two bottles of identical drink in different flavours
is one way to get around it," said Shirreffs.
Mimic Race Conditions As Closely as Possible
Whatever you try, you need to practice it when gastric emptying is
at its worst. That means mimicking race conditions. A common pitfall
riders fall into is trying out re-fuelling strategies on long, but
easy, training rides. Come race day, the higher intensity will
change the way your stomach reacts and could ruin everything. So if
you're going to train your gut you need to do it at race pace, or
even faster.
"Small, regular sips during sessions faster than race pace will
increase your ability to consume and digest the fluids, calories,
and electrolytes in your energy drink of choice," said Dr. Misner.
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