Pre and post workout nutrition?

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Real Thought for Food for Long Workouts

By GINA KOLATA

Published: June 5, 2008

http://www.nytimes.com/2008/06/05/health/nutrition/05Best.html?

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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 , 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. 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 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. 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. 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. said, he simply eats real food at regular meals.

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Carruthers

Wakefield, UK