Funny, I just yesterday sent an email to an exercise physiologist
about this very topic. Several years ago a coach at Silverstar
admonished me for drinking Gatorade on an LSD ski, saying that it
predisposed me to using carbohydrate as fuel rather than fat. Everyone
I subsequently asked about this gave me a blank stare.

Whether that is true or not, I have another question: do we care about
using fat for energy for races at which we are almost immediately
racing at lactate threshold or higher?

Background:
Exercise physiologists use various measurements to determine lactate
threshold. One of those measurements is the Respiratory Exchange Ratio
(RER) which is apparently a good indicator of fuel utilization. RER is
the volume of Co2 divided by the volume of O2. We ventilate off
different percentages of O2 and Co2 which indicate whether we are
using carbohydrate vs fat for fuel. During a stress test, as we
approach lactate threshold we increasingly use carbohydrate. Over LT,
we are using almost all carbohydrate.

So, in races where you are operating at LT or greater, do we even care
if our body is predisposed to carbohydrate metabolism, since that is
what we're using anyway? Or is there still some small amount of fat
utilization going on, any bit of which we want to hang on to?

Obviously, for some folks racing 30-50km races, the research might be
very relevant since you might be racing at lower than LT and your
carbohydrate stores will presumably not last the entire race: you want
your body predisposed to using fat whenever it can.

I looked up the research by Bengt Saltin (you can too at
http://www.ncbi.nlm.nih.gov/entrez). I believe it is this article:

Glucose ingestion blunts hormone-sensitive lipase activity in
contracting human skeletal muscle.
Am J Physiol Endocrinol Metab. 2004 Jan;286(1):E144-50. Epub 2003 Sep
23


Torsten

"Gary Jacobson" wrote in message ...
A buddy of mine who is a monster endurance athlete used to tell me he
"intuitively" knew that feeding with carbohydrates when training prevented
best use of fat for metabolism and trained the body to need carbohydrate.
This was about 15 years ago.

I just read a summary of a study by Bengt Saltin, said to be a leading
sports physician. My buddy's contention is apparently supported. Here's the
blurb from http://www.jenex.com/news/index.html.:

One of the world's foremost Sports Medicine doctors, Bengt Saltin, who won
the IOC Sports Medicine prize in 2002 suspected that training for endurance
while using "sports drinks" and power bars might not the best way to develop
the body for optimal results in long distance races. ( Of course the sports
drinks power bar companies will try to prove him wrong. A well recognized US
Researcher told me that the difference between studies in Scandinavia and
the US is that in the States many studies are biased because major food and
soft drink firms sponsor the studies. The purse strings for sports research
in the US are mainly the marketing giants and without the money, no
research. In Scandinavia, Universities generally fund the studies. About ten
years ago I was indirectly involved with a University study on an exercise
product. The manufacturer of the product was convinced the device was an
exercise marvel and wanted a University study to back their marketing
claims. When the study showed that power walking was more beneficial than
their exercise device, the study was not allowed to be presented. The Doctor
who performed the study was obviously upset, but the study was funded by the
company and he was not allowed to publish it. )

It is well documented that you need maximum carbohydrate loading for long
distance races, but what if the body was better able to use both sugar and
fat for fuel? Most endurance athletes train using the same sports drinks as
when racing. However, Professor Saltin said that a few years ago he began to
question this method for training. Since we have more fat deposits for
energy than sugar it is important to be able to utilize both energy sources
optimally in long distance races. Bengt Saltin suspected that if we train
while consuming sugar drinks, the body would have fewer fat burning enzymes.
With sugar available, the enzymes are not needed so they don't get
developed.

Bengt first tested his theory at the University in Copenhagen, then a study
was made in Sweden on 18 skiers divided into two groups of nine. In the ski
study, which lasted for eight weeks, the two groups trained three times a
week for 1.5 hours and on the fourth day for approximately three hours. One
group used a well known sports drink while the others drank only water while
training and did not take any carbohydrates for at least one hour after
training. Prior to the experiment, biopsies were taken on all athletes.
After the eight weeks, new biopsies showed that the group that used only
water had substantially more important enzymes for the burning of fat. So in
race conditions, the water consuming group could better utilize the two
available fuel sources, sugar and fat. This month Bengt Saltin is starting a
third study of the potential benefits of reduced carbohydrate intake while
training for endurance races.

Gary (Got Hammer Gel?) Jacobson
Rosendale, NY