Scott Kolasinski
06-27-2008, 05:15 AM
I had copied and pasted this article on another forum with a quick take on it and I got one reply from Jose Antonio. I also asked Dr. John Ivy for his view on the article. I'll post all following this post.
http://www.nytimes.com/2008/06/05/health/nutrition/05Best.html?em&ex=1212897600&\
en=59ceee170b36f528&ei=5087%0A
By GINA KOLATA
Published: June 5, 2008
DR. MARK TARNOPOLSKY, a muscle physiology researcher at McMaster
University in Canada and a physician, knows all about the exhortations
by supplement makers and many nutritionists on what to eat and when to
eat it for optimal performance.
The idea is that you are supposed to consume carbohydrates and
proteins in a magical four-to-one ratio during endurance events like a
long run or bike ride, and right after. The belief is that such
nutritional diligence will improve your performance and speed your
recovery.
Dr. Tarnopolsky, a 45-year-old trail runner and adventure racer, might
be expected to seize upon the nutritional advice. (He won the Ontario
trail running series in 2004, 2005 and 2006.)
So might his colleague, Stuart Phillips, a 41-year-old associate
professor of kinesiology at McMaster who played rugby for Canada's
national team and now plays it for fun. He also runs, lifts weights
and studies nutrition and performance.
In fact, neither researcher regularly uses energy drinks or energy
bars. They just drink water, and eat real food. Dr. Tarnopolsky drinks
fruit juice; Dr. Phillips eats fruit. And neither one feels a need to
ingest a special combination of protein and carbohydrates within a
short window of time, a few hours after exercising.
There are grains of truth to the nutrition advice, they and other
experts say. But, as so often happens in sports, those grains of truth
have been expanded into dictums and have formed the basis for an
entire industry in "recovery" products.
They line the shelves of specialty sports stores and supermarkets with
names like Accelerade drink, Endurox R4 powder, PowerBar Recovery bar.
"It does seem to me that as a group, athletes are particularly
gullible," said Michael Rennie, a physiologist at the University of
Nottingham in England who studies muscle metabolism.
The idea that what you eat and when you eat it will make a big
difference in your performance and recovery "is wishful thinking,"
said Dr. Rennie, a 61-year-old who was a competitive swimmer and also
used to play water polo and rugby.
Here is what is known about proteins, carbohydrates and performance.
During exercise, muscles stop the biochemical reactions used to
maintain themselves such as replacing and resynthesizing the proteins
needed for day to day activities. It's not that exercise is damaging
your muscles; it's that they halt the maintenance process until
exercise is over.
To do this maintenance, muscles must make protein, and to do so they
need to absorb amino acids, the constituent parts of proteins, from
the blood. Just after exercise, perhaps for a period no longer than a
couple of hours, the protein-building processes of muscle cells are
especially receptive to amino acids. That means that if you consume
protein, your muscles will use it to quickly replenish proteins that
were not made during exercise.
But muscles don't need much protein, researchers say. Twenty grams is
as much as a 176-pound man's muscles can take. Women, who are smaller
and have smaller muscles even compared to their body sizes, need less.
Dr. Rennie said that 10 to 15 grams of protein is probably adequate
for any adult. And you don't need a special drink or energy bar to get
it. One egg has 6 grams of protein. Two ounces of chicken has more
than 12 grams.
Muscles also need to replenish glycogen, their fuel supply, after a
long exercise session — two hours of running, for example. For that
they need carbohydrates. Muscle cells are especially efficient in
absorbing carbohydrates from the blood just after exercise.
Once again, muscles don't need much; about one gram of carbohydrate
per kilogram of body weight is plenty, Dr. Tarnopolsky said. He weighs
70 kilograms, or 154 pounds, which means he would need 70 grams of
carbohydrates, or say, 27 ounces of fruit juice, he said.
Asker Jeukendrup, a 38-year-old 14-time Ironman-distance finisher who
is an exercise physiologist and nutritionist at the University of
Birmingham in England said the fastest glycogen replacement takes
place in the four hours after exercise. Even so, most athletes need
not worry.
"Most athletes will have at least 24 hours to recover," Dr. Jeukendrup
said. "We really are talking about a group of extremely elite sports
people who train twice a day." For them, he said, it can be necessary
to rapidly replenish muscle glycogen.
The American College of Sports Medicine, in a position paper written
by leading experts, reported that athletes who take a day or two to
rest or do less-intense workouts between vigorous sessions can pretty
much ignore the carbohydrate-timing advice.
The group wrote that for these athletes, "when sufficient carbohydrate
is provided over a 24-hour period, the timing of intake does not
appear to affect the amount of glycogen stored."
For protein, it is not clear what the window is. Some studies
concluded it was less than two hours, others said three hours, and
some failed to find a window at all.
Dr. Rennie and his colleagues, writing in Annual Reviews of
Physiology, concluded that "a possible `golden period' " for getting
amino acids into muscles "remains a speculative, no matter how
attractive, the concept."
Although studies by Dr. Jeukendrup and several others have shown that
consuming protein after exercise speeds up muscle protein synthesis,
no one has shown that that translates into improved performance. The
reason, Dr. Jeukendrup said, is that effects on performance, if they
occur, won't happen immediately. They can take 6 to 10 weeks of
training. That makes it very hard to design and carry out studies to
see if athletes really do improve if they consume protein after they
exercise.
"You'd have to control everything, what they do, how they train, and
also their carbohydrate and protein intake," Dr. Jeukendrup said.
"Those studies become almost impossible to do."
As for the special four-to-one ratio of carbohydrates to protein,
that, too, is not well established, researchers said. The idea was
that you need both carbohydrates and protein consumed together because
carbohydrates not only help muscles restore their glycogen but they
also elicit the release of insulin. Insulin, the theory goes, helps
muscles absorb amino acids.
Insulin may stimulate muscle protein synthesis in young rodents and in
human cells grown in petri dishes, Dr. Rennie said. But studies in
people have shown convincingly that insulin is not required for
protein synthesis in adult human beings; it is amino acids that drive
protein synthesis. As yet no convincing evidence exists that a special
carbohydrate-to-protein ratio makes a noticeable difference in muscle
protein maintenance after exercise. "There is no magic ratio," Dr.
Jeukendrup said.
The American College of Sports Medicine is equally skeptical. "Adding
protein does not appreciably enhance glycogen repletion," its paper
states.
"Some studies suggested that adding proteins to carbohydrates during
exercise can enhance performance," Dr. Tarnopolsky said. "Many other
studies suggested it didn't do any good."
Even if there are effects of protein and carbohydrates, they are not
important to most exercisers, these researchers say. Serious
triathletes and elite runners, who work out in the morning and at
night, need to eat between training sessions. But people who are
running a few miles a few days a week don't need to worry about
replenishing their muscles, Dr. Phillips said.
Dr. Rennie agreed. "If you are a superathlete, hundredths of a second
matter," he said. "But most Joes and Janes are just kidding
themselves," he said.
Some, like Dr. Jeukendrup, say they use a commercial protein-energy
drink after training hard, for convenience.
Other researchers take their own nutritional advice. Dr. Tarnopolsky
has a huge glass of juice, a bagel and a small piece of meat after a
two- or three-hour run. Or he might have two large pieces of toast
with butter and jam and a couple of scrambled eggs. But no energy
bars, no energy drinks.
Dr. Phillips might have an energy bar during a long workout. But
ordinarily he does not worry about getting a special
carbohydrate-to-protein mix or timing his nutrition when he exercises.
Instead, Dr. Phillips said, he simply eats real food at regular meals.
http://www.nytimes.com/2008/06/05/health/nutrition/05Best.html?em&ex=1212897600&\
en=59ceee170b36f528&ei=5087%0A
By GINA KOLATA
Published: June 5, 2008
DR. MARK TARNOPOLSKY, a muscle physiology researcher at McMaster
University in Canada and a physician, knows all about the exhortations
by supplement makers and many nutritionists on what to eat and when to
eat it for optimal performance.
The idea is that you are supposed to consume carbohydrates and
proteins in a magical four-to-one ratio during endurance events like a
long run or bike ride, and right after. The belief is that such
nutritional diligence will improve your performance and speed your
recovery.
Dr. Tarnopolsky, a 45-year-old trail runner and adventure racer, might
be expected to seize upon the nutritional advice. (He won the Ontario
trail running series in 2004, 2005 and 2006.)
So might his colleague, Stuart Phillips, a 41-year-old associate
professor of kinesiology at McMaster who played rugby for Canada's
national team and now plays it for fun. He also runs, lifts weights
and studies nutrition and performance.
In fact, neither researcher regularly uses energy drinks or energy
bars. They just drink water, and eat real food. Dr. Tarnopolsky drinks
fruit juice; Dr. Phillips eats fruit. And neither one feels a need to
ingest a special combination of protein and carbohydrates within a
short window of time, a few hours after exercising.
There are grains of truth to the nutrition advice, they and other
experts say. But, as so often happens in sports, those grains of truth
have been expanded into dictums and have formed the basis for an
entire industry in "recovery" products.
They line the shelves of specialty sports stores and supermarkets with
names like Accelerade drink, Endurox R4 powder, PowerBar Recovery bar.
"It does seem to me that as a group, athletes are particularly
gullible," said Michael Rennie, a physiologist at the University of
Nottingham in England who studies muscle metabolism.
The idea that what you eat and when you eat it will make a big
difference in your performance and recovery "is wishful thinking,"
said Dr. Rennie, a 61-year-old who was a competitive swimmer and also
used to play water polo and rugby.
Here is what is known about proteins, carbohydrates and performance.
During exercise, muscles stop the biochemical reactions used to
maintain themselves such as replacing and resynthesizing the proteins
needed for day to day activities. It's not that exercise is damaging
your muscles; it's that they halt the maintenance process until
exercise is over.
To do this maintenance, muscles must make protein, and to do so they
need to absorb amino acids, the constituent parts of proteins, from
the blood. Just after exercise, perhaps for a period no longer than a
couple of hours, the protein-building processes of muscle cells are
especially receptive to amino acids. That means that if you consume
protein, your muscles will use it to quickly replenish proteins that
were not made during exercise.
But muscles don't need much protein, researchers say. Twenty grams is
as much as a 176-pound man's muscles can take. Women, who are smaller
and have smaller muscles even compared to their body sizes, need less.
Dr. Rennie said that 10 to 15 grams of protein is probably adequate
for any adult. And you don't need a special drink or energy bar to get
it. One egg has 6 grams of protein. Two ounces of chicken has more
than 12 grams.
Muscles also need to replenish glycogen, their fuel supply, after a
long exercise session — two hours of running, for example. For that
they need carbohydrates. Muscle cells are especially efficient in
absorbing carbohydrates from the blood just after exercise.
Once again, muscles don't need much; about one gram of carbohydrate
per kilogram of body weight is plenty, Dr. Tarnopolsky said. He weighs
70 kilograms, or 154 pounds, which means he would need 70 grams of
carbohydrates, or say, 27 ounces of fruit juice, he said.
Asker Jeukendrup, a 38-year-old 14-time Ironman-distance finisher who
is an exercise physiologist and nutritionist at the University of
Birmingham in England said the fastest glycogen replacement takes
place in the four hours after exercise. Even so, most athletes need
not worry.
"Most athletes will have at least 24 hours to recover," Dr. Jeukendrup
said. "We really are talking about a group of extremely elite sports
people who train twice a day." For them, he said, it can be necessary
to rapidly replenish muscle glycogen.
The American College of Sports Medicine, in a position paper written
by leading experts, reported that athletes who take a day or two to
rest or do less-intense workouts between vigorous sessions can pretty
much ignore the carbohydrate-timing advice.
The group wrote that for these athletes, "when sufficient carbohydrate
is provided over a 24-hour period, the timing of intake does not
appear to affect the amount of glycogen stored."
For protein, it is not clear what the window is. Some studies
concluded it was less than two hours, others said three hours, and
some failed to find a window at all.
Dr. Rennie and his colleagues, writing in Annual Reviews of
Physiology, concluded that "a possible `golden period' " for getting
amino acids into muscles "remains a speculative, no matter how
attractive, the concept."
Although studies by Dr. Jeukendrup and several others have shown that
consuming protein after exercise speeds up muscle protein synthesis,
no one has shown that that translates into improved performance. The
reason, Dr. Jeukendrup said, is that effects on performance, if they
occur, won't happen immediately. They can take 6 to 10 weeks of
training. That makes it very hard to design and carry out studies to
see if athletes really do improve if they consume protein after they
exercise.
"You'd have to control everything, what they do, how they train, and
also their carbohydrate and protein intake," Dr. Jeukendrup said.
"Those studies become almost impossible to do."
As for the special four-to-one ratio of carbohydrates to protein,
that, too, is not well established, researchers said. The idea was
that you need both carbohydrates and protein consumed together because
carbohydrates not only help muscles restore their glycogen but they
also elicit the release of insulin. Insulin, the theory goes, helps
muscles absorb amino acids.
Insulin may stimulate muscle protein synthesis in young rodents and in
human cells grown in petri dishes, Dr. Rennie said. But studies in
people have shown convincingly that insulin is not required for
protein synthesis in adult human beings; it is amino acids that drive
protein synthesis. As yet no convincing evidence exists that a special
carbohydrate-to-protein ratio makes a noticeable difference in muscle
protein maintenance after exercise. "There is no magic ratio," Dr.
Jeukendrup said.
The American College of Sports Medicine is equally skeptical. "Adding
protein does not appreciably enhance glycogen repletion," its paper
states.
"Some studies suggested that adding proteins to carbohydrates during
exercise can enhance performance," Dr. Tarnopolsky said. "Many other
studies suggested it didn't do any good."
Even if there are effects of protein and carbohydrates, they are not
important to most exercisers, these researchers say. Serious
triathletes and elite runners, who work out in the morning and at
night, need to eat between training sessions. But people who are
running a few miles a few days a week don't need to worry about
replenishing their muscles, Dr. Phillips said.
Dr. Rennie agreed. "If you are a superathlete, hundredths of a second
matter," he said. "But most Joes and Janes are just kidding
themselves," he said.
Some, like Dr. Jeukendrup, say they use a commercial protein-energy
drink after training hard, for convenience.
Other researchers take their own nutritional advice. Dr. Tarnopolsky
has a huge glass of juice, a bagel and a small piece of meat after a
two- or three-hour run. Or he might have two large pieces of toast
with butter and jam and a couple of scrambled eggs. But no energy
bars, no energy drinks.
Dr. Phillips might have an energy bar during a long workout. But
ordinarily he does not worry about getting a special
carbohydrate-to-protein mix or timing his nutrition when he exercises.
Instead, Dr. Phillips said, he simply eats real food at regular meals.